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  • ArrayList access

    - by Ricky McQuesten
    So once again I have a question about this program. I want to store transactions that are made in an arraylist and then have an option in the case menu where I can print out those that are stored. I have been researching online and have been unable to find a solution to this, so is this possible and how would I go about doing this? I also want to attach a timestamp to each transaction as well. Here is the code I have so far. So my question is how would I add a timestamp to each withdrawal or deposit, and how would I store each transaction in array list? import java.util.*; public class BankAccount extends Money { //inheritence static String name; public static int acctNum; public static double balance, amount; BankAccount(String name, int accNo, double bal) { this.name = name; this.acctNum = accNo; this.balance = bal; } void display() { System.out.println("Your Name:" + name); System.out.println("Your Account Number:" + acctNum); System.out.println("Your Current Account Balance:" + Money.getBalance()); } void displayBalance() { System.out.println("Balance:" + balance); } } import java.util.Scanner; /** * * @author Ricky */ public class Money { public static int accountNumber; public static double balance; static double amount; static String name; public void setDeposit(double amount) { balance = balance + amount; if (amount < 0) { System.out.println("Invalid"); } } public double getDeposit() { return 1; } public void setBalance(double b) { balance = b; } public static double getBalance() { return balance; } public void setWithdraw(double amount) { if (balance < amount) { System.out.println("Not enough funds."); } else if(amount < 0) { System.out.println("Invalid"); } else { balance = balance - amount; } } public double getWithdraw() { return 1; } } import java.util.*; public class Client { public static void main(String args[]) { int n = 0; int count; String trans; ArrayList<String> transaction= new ArrayList<String>(n); Scanner input = new Scanner(System.in); System.out.println("Welcome to First National Bank"); System.out.println("Please enter your name: "); String cusName = input.nextLine(); System.out.println("You will now be assigned an account number."); Random randomGenerator = new Random(); int accNo = randomGenerator.nextInt(100000); //random number System.out.println("Your account number is: " + accNo); System.out.println("Please enter your initial account balance: "); Double balance = input.nextDouble(); BankAccount b1 = new BankAccount(cusName, accNo, balance); b1.setBalance(balance); int menu; /*System.out.println("Menu"); System.out.println("1. Deposit Amount"); System.out.println("2. Withdraw Amount"); System.out.println("3. Display Information"); System.out.println("4. Exit");*/ boolean quit = false; do { System.out.println("*******Menu*******"); System.out.println("1. Deposit Amount"); // menu to take input from user System.out.println("2. Withdraw Amount"); System.out.println("3. Display Information"); System.out.println("4. Exit"); System.out.print("Please enter your choice: "); menu = input.nextInt(); switch (menu) { case 1: System.out.print("Enter depost amount:"); b1.setDeposit(input.nextDouble()); b1.getDeposit(); transaction.add(trans); break; case 2: System.out.println("Current Account Balance=" + b1.getBalance()); System.out.print("Enter withdrawal amount:"); b1.setWithdraw(input.nextDouble()); b1.getWithdraw(); transaction.add(trans); break; // switch statments to do a loop case 3: b1.display(); break; case 4: quit = true; break; } } while (!quit); } } public class Date { static Date time = new Date(); }

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  • Saving image from Gallery to db - Coursor IllegalStateException

    - by MyWay
    I want to save to db some strings with image. Image can be taken from gallery or user can set the sample one. In the other activity I have a listview which should present the rows with image and name. I'm facing so long this problem. It occurs when I wanna display listview with the image from gallery, If the sample image is saved in the row everything works ok. My problem is similar to this one: how to save image taken from camera and show it to listview - crashes with "IllegalStateException" but I can't find there the solution for me My table in db looks like this: public static final String KEY_ID = "_id"; public static final String ID_DETAILS = "INTEGER PRIMARY KEY AUTOINCREMENT"; public static final int ID_COLUMN = 0; public static final String KEY_NAME = "name"; public static final String NAME_DETAILS = "TEXT NOT NULL"; public static final int NAME_COLUMN = 1; public static final String KEY_DESCRIPTION = "description"; public static final String DESCRIPTION_DETAILS = "TEXT"; public static final int DESCRIPTION_COLUMN = 2; public static final String KEY_IMAGE ="image" ; public static final String IMAGE_DETAILS = "BLOP"; public static final int IMAGE_COLUMN = 3; //method which create our table private static final String CREATE_PRODUCTLIST_IN_DB = "CREATE TABLE " + DB_TABLE + "( " + KEY_ID + " " + ID_DETAILS + ", " + KEY_NAME + " " + NAME_DETAILS + ", " + KEY_DESCRIPTION + " " + DESCRIPTION_DETAILS + ", " + KEY_IMAGE +" " + IMAGE_DETAILS + ");"; inserting statement: public long insertToProductList(String name, String description, byte[] image) { ContentValues value = new ContentValues(); // get the id of column and value value.put(KEY_NAME, name); value.put(KEY_DESCRIPTION, description); value.put(KEY_IMAGE, image); // put into db return db.insert(DB_TABLE, null, value); } Button which add the picture and onActivityResult method which saves the image and put it into the imageview public void AddPicture(View v) { // creating specified intent which have to get data Intent intent = new Intent(Intent.ACTION_PICK); // From where we want choose our pictures intent.setType("image/*"); startActivityForResult(intent, PICK_IMAGE); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { // TODO Auto-generated method stub super.onActivityResult(requestCode, resultCode, data); // if identification code match to the intent, //if yes we know that is our picture, if(requestCode ==PICK_IMAGE ) { // check if the data comes with intent if(data!= null) { Uri chosenImage = data.getData(); String[] filePathColumn = {MediaStore.Images.Media.DATA}; Cursor cursor = getContentResolver().query(chosenImage, filePathColumn, null, null, null); cursor.moveToFirst(); int columnIndex = cursor.getColumnIndex(filePathColumn[0]); String filePat = cursor.getString(columnIndex); cursor.close(); ImageOfProduct = BitmapFactory.decodeFile(filePat); if(ImageOfProduct!=null) { picture.setImageBitmap(ImageOfProduct); } messageDisplayer("got picture, isn't null " + IdOfPicture); } } } Then the code which converts bitmap to byte[] public byte[] bitmapToByteConvert(Bitmap bit ) { // stream of data getted for compressed bitmap ByteArrayOutputStream gettedData = new ByteArrayOutputStream(); // compressing method bit.compress(CompressFormat.PNG, 0, gettedData); // our byte array return gettedData.toByteArray(); } The method which put data to the row: byte[] image=null; // if the name isn't put to the editView if(name.getText().toString().trim().length()== 0) { messageDisplayer("At least you need to type name of product if you want add it to the DB "); } else{ String desc = description.getText().toString(); if(description.getText().toString().trim().length()==0) { messageDisplayer("the description is set as none"); desc = "none"; } DB.open(); if(ImageOfProduct!= null){ image = bitmapToByteConvert(ImageOfProduct); messageDisplayer("image isn't null"); } else { BitmapDrawable drawable = (BitmapDrawable) picture.getDrawable(); image = bitmapToByteConvert(drawable.getBitmap()); } if(image.length>0 && image!=null) { messageDisplayer(Integer.toString(image.length)); } DB.insertToProductList(name.getText().toString(), desc, image ); DB.close(); messageDisplayer("well done you add the product"); finish(); You can see that I'm checking here the length of array to be sure that I don't send empty one. And here is the place where Error appears imo, this code is from activity which presents the listview with data taken from db private void LoadOurLayoutListWithInfo() { // firstly wee need to open connection with db db= new sqliteDB(getApplicationContext()); db.open(); // creating our custom adaprer, the specification of it will be typed // in our own class (MyArrayAdapter) which will be created below ArrayAdapter<ProductFromTable> customAdapter = new MyArrayAdapter(); //get the info from whole table tablecursor = db.getAllColumns(); if(tablecursor != null) { startManagingCursor(tablecursor); tablecursor.moveToFirst(); } // now we moving all info from tablecursor to ourlist if(tablecursor != null && tablecursor.moveToFirst()) { do{ // taking info from row in table int id = tablecursor.getInt(sqliteDB.ID_COLUMN); String name= tablecursor.getString(sqliteDB.NAME_COLUMN); String description= tablecursor.getString(sqliteDB.DESCRIPTION_COLUMN); byte[] image= tablecursor.getBlob(3); tablefromDB.add(new ProductFromTable(id,name,description,image)); // moving until we didn't find last row }while(tablecursor.moveToNext()); } listView = (ListView) findViewById(R.id.tagwriter_listoftags); //as description says // setAdapter = The ListAdapter which is responsible for maintaining //the data backing this list and for producing a view to represent //an item in that data set. listView.setAdapter(customAdapter); } I put the info from row tho objects which are stored in list. I read tones of question but I can't find any solution for me. Everything works when I put the sample image ( which is stored in app res folder ). Thx for any advice

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  • How to correctly populate records from SQLlite in ListActivity?

    - by Pavel
    Hi. Can someone please tell me how can I easily display every record from sqllite in ListActivity tab? I'm kinda confused with this. Do I have to create db from my helper class in TabActivity or ListActivity or both? My db helper class is as follow: package tabs.app; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; import android.util.Log; public class DBAdapter { private static String DB_PATH = "/data/data/tabs.app/databases/"; public static final String KEY_ROWID = "_id"; public static final String KEY_LATITUDE = "latitude"; public static final String KEY_LONGITUDE = "longitude"; private static final String TAG = "DBAdapter"; private static final String DATABASE_NAME = "coords"; private static final String DATABASE_TABLE = "coordsStorages"; private static final int DATABASE_VERSION = 2; /* private static final String DATABASE_CREATE = "create table coordsStorage (_id integer primary key autoincrement, latitude integer not null, longitude integer not null)"; */ public Context context; private DatabaseHelper DBHelper; private SQLiteDatabase db; public DBAdapter(Context ctx) { this.context = ctx; DBHelper = new DatabaseHelper(context); } private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL("create table coordsStorages (_id integer primary key autoincrement, latitude integer not null, longitude integer not null)"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion + ", which will destroy all old data"); db.execSQL("DROP TABLE IF EXISTS titles"); onCreate(db); } } //---opens the database--- public DBAdapter open() throws SQLException { db = DBHelper.getWritableDatabase(); return this; } //---closes the database--- public void close() { DBHelper.close(); } //---insert a title into the database--- public long insertCoords(int latitude, int longitude) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_LATITUDE, latitude); initialValues.put(KEY_LONGITUDE, longitude); return db.insert(DATABASE_TABLE, null, initialValues); } public void openDataBase() throws SQLException{ //Open the database String myPath = DB_PATH + DATABASE_NAME; db = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); } //---deletes a particular title--- public boolean deleteTitle(long rowId) { return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0; } //---retrieves all the titles--- public Cursor getAllTitles() { return db.query(DATABASE_TABLE, new String[] { KEY_ROWID, KEY_LATITUDE, KEY_LONGITUDE}, null, null, null, null, null); } //---retrieves a particular title--- public Cursor getTitle(long rowId) throws SQLException { Cursor mCursor = db.query(true, DATABASE_TABLE, new String[] { KEY_ROWID, KEY_LATITUDE, KEY_LONGITUDE}, KEY_ROWID + "=" + rowId, null, null, null, null, null); if (mCursor != null) { mCursor.moveToFirst(); } return mCursor; } //---updates a title--- /*public boolean updateTitle(long rowId, int latitude, int longitude) { ContentValues args = new ContentValues(); args.put(KEY_LATITUDE, latitude); args.put(KEY_LONGITUDE, longitude); return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0; }*/ } And Im trying to retrieve the records in TabActivity like this: public class Areas extends ListActivity { DBAdapter db; SimpleCursorAdapter mAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.areas_layout); db = new DBAdapter(this); db.open(); Cursor c = db.getAllTitles(); startManagingCursor(c); String[] display = new String[] { db.KEY_LATITUDE }; int[] to = new int[] { R.id.row_latitude}; /* String[] display2 = new String[] { db.KEY_LONGITUDE }; int[] to2 = new int[] { R.id.row_longitude};*/ mAdapter = new SimpleCursorAdapter(this, R.layout.areas_layout, c, display, to); setListAdapter(mAdapter); /* mAdapter2 = new SimpleCursorAdapter(this, R.layout.areas_layout, c, display2, to2); setListAdapter(mAdapter2);*/ db.close(); } /* private void fillData() { // Get all of the rows from the database and create the item list Cursor c = db.getAllTitles(); startManagingCursor(c); }*/ } Whenever I'm trying to do that the error log outputs this: 06-07 09:51:56.529: ERROR/AndroidRuntime(2034): Uncaught handler: thread main exiting due to uncaught exception 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): java.lang.RuntimeException: Unable to start activity ComponentInfo{tabs.app/tabs.app.Areas}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list' 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2401) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.app.ActivityThread.startActivityNow(ActivityThread.java:2242) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:127) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:339) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:631) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.widget.TabHost.setCurrentTab(TabHost.java:317) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.widget.TabHost$2.onTabSelectionChanged(TabHost.java:127) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.widget.TabWidget$TabClickListener.onClick(TabWidget.java:346) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.view.View.performClick(View.java:2344) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.view.View.onTouchEvent(View.java:4133) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.view.View.dispatchTouchEvent(View.java:3672) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:850) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1712) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1202) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.app.Activity.dispatchTouchEvent(Activity.java:1987) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1696) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.view.ViewRoot.handleMessage(ViewRoot.java:1658) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.os.Handler.dispatchMessage(Handler.java:99) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.os.Looper.loop(Looper.java:123) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.app.ActivityThread.main(ActivityThread.java:4203) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at java.lang.reflect.Method.invokeNative(Native Method) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at java.lang.reflect.Method.invoke(Method.java:521) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at dalvik.system.NativeStart.main(Native Method) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): Caused by: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list' 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.app.ListActivity.onContentChanged(ListActivity.java:236) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:316) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.app.Activity.setContentView(Activity.java:1620) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at tabs.app.Areas.onCreate(Areas.java:18) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2364) 06-07 09:51:56.559: ERROR/AndroidRuntime(2034): ... 30 more 06-07 09:51:56.619: INFO/Process(51): Sending signal. PID: 2034 SIG: 3 06-07 09:51:56.619: INFO/dalvikvm(2034): threadid=7: reacting to signal 3 06-07 09:51:56.619: ERROR/dalvikvm(2034): Unable to open stack trace file '/data/anr/traces.txt': Permission denied Can someone please tell me what I'm doing wrong? Help greatly appreciated!

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  • MVC4 Model in View has nested data - cannot get data in model

    - by Taersious
    I have a Model defined that gets me a View with a list of RadioButtons, per IEnumerable. Within that Model, I want to display a list of checkboxes that will vary based on the item selected. Finally, there will be a Textarea in the same view once the user has selected from the available checkboxes, with some dynamic text there based on the CheckBoxes that are selected. What we should end up with is a Table-per-hierarchy. The layout is such that the RadioButtonList is in the first table cell, the CheckBoxList is in the middle table cell, and the Textarea is ini the right table cell. If anyone can guide me to what my model-view should be to achieve this result, I'll be most pleased... Here are my codes: // // View Model for implementing radio button list public class RadioButtonViewModel { // objects public List<RadioButtonItem> RadioButtonList { get; set; } public string SelectedRadioButton { get; set; } } // // Object for handling each radio button public class RadioButtonItem { // this object public string Name { get; set; } public bool Selected { get; set; } public int ObjectId { get; set; } // columns public virtual IEnumerable<CheckBoxItem> CheckBoxItems { get; set; } } // // Object for handling each checkbox public class CheckBoxViewModel { public List<CheckBoxItem> CheckBoxList { get; set; } } // // Object for handling each check box public class CheckBoxItem { public string Name { get; set; } public bool Selected { get; set; } public int ObjectId { get; set; } public virtual RadioButtonItem RadioButtonItem { get; set; } } and the view @model IEnumerable<EF_Utility.Models.RadioButtonItem> @{ ViewBag.Title = "Connect"; ViewBag.Selected = Request["name"] != null ? Request["name"].ToString() : ""; } @using (Html.BeginForm("Objects" , "Home", FormMethod.Post) ){ @Html.ValidationSummary(true) <table> <tbody> <tr> <td style="border: 1px solid grey; vertical-align:top;"> <table> <tbody> <tr> <th style="text-align:left; width: 50px;">Select</th> <th style="text-align:left;">View or Table Name</th> </tr> @{ foreach (EF_Utility.Models.RadioButtonItem item in @Model ) { <tr> <td> @Html.RadioButton("RadioButtonViewModel.SelectedRadioButton", item.Name, ViewBag.Selected == item.Name ? true : item.Selected, new { @onclick = "this.form.action='/Home/Connect?name=" + item.Name + "'; this.form.submit(); " }) </td> <td> @Html.DisplayFor(i => item.Name) </td> </tr> } } </tbody> </table> </td> <td style="border: 1px solid grey; width: 220px; vertical-align:top; @(ViewBag.Selected == "" ? "display:none;" : "")"> <table> <tbody> <tr> <th>Column </th> </tr> <tr> <td><!-- checkboxes will go here --> </td> </tr> </tbody> </table> </td> <td style="border: 1px solid grey; vertical-align:top; @(ViewBag.Selected == "" ? "display:none;" : "")"> <textarea name="output" id="output" rows="24" cols="48"></textarea> </td> </tr> </tbody> </table> } and the relevant controller public ActionResult Connect() { /* TEST SESSION FIRST*/ if( Session["connstr"] == null) return RedirectToAction("Index"); else { ViewBag.Message = ""; ViewBag.ConnectionString = Server.UrlDecode( Session["connstr"].ToString() ); ViewBag.Server = ParseConnectionString( ViewBag.ConnectionString, "Data Source" ); ViewBag.Database = ParseConnectionString( ViewBag.ConnectionString, "Initial Catalog" ); using( var db = new SysDbContext(ViewBag.ConnectionString)) { var objects = db.Set<SqlObject>().ToArray(); var model = objects .Select( o => new RadioButtonItem { Name = o.Name, Selected = false, ObjectId = o.Object_Id, CheckBoxItems = Enumerable.Empty<EF_Utility.Models.CheckBoxItem>() } ) .OrderBy( rb => rb.Name ); return View( model ); } } } What I am missing it seems, is the code in my Connect() method that will bring the data context forward; at that point, it should be fairly straight-forward to set up the Html for the View. EDIT ** So I am going to need to bind the RadioButtonItem to the view with something like the following, except my CheckBoxList will NOT be an empty set. // // POST: /Home/Connect/ [HttpPost] public ActionResult Connect( RadioButtonItem rbl ) { /* TEST SESSION FIRST*/ if ( Session["connstr"] == null ) return RedirectToAction( "Index" ); else { ViewBag.Message = ""; ViewBag.ConnectionString = Server.UrlDecode( Session["connstr"].ToString() ); ViewBag.Server = ParseConnectionString( ViewBag.ConnectionString, "Data Source" ); ViewBag.Database = ParseConnectionString( ViewBag.ConnectionString, "Initial Catalog" ); using ( var db = new SysDbContext( ViewBag.ConnectionString ) ) { var objects = db.Set<SqlObject>().ToArray(); var model = objects .Select( o => new RadioButtonItem { Name = o.Name, Selected = false, ObjectId = o.Object_Id, CheckBoxItems = Enumerable.Empty<EF_Utility.Models.CheckBoxItem>() } ) .OrderBy( rb => rb.Name ); return View( model ); } } }

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  • Unexpected ArrayIndexOutOfBoundsException in JavaFX application, refering to no array

    - by Eugene
    I have the following code: public void setContent(Importer3D importer) { if (DEBUG) { System.out.println("Initialization of Mesh's arrays"); } coords = importer.getCoords(); texCoords = importer.getTexCoords(); faces = importer.getFaces(); if (DEBUG) { System.out.println("Applying Mesh's arrays"); } mesh = new TriangleMesh(); mesh.getPoints().setAll(coords); mesh.getTexCoords().setAll(texCoords); mesh.getFaces().setAll(faces); if (DEBUG) { System.out.println("Initialization of the material"); } initMaterial(); if (DEBUG) { System.out.println("Setting the MeshView"); } meshView.setMesh(mesh); meshView.setMaterial(material); meshView.setDrawMode(DrawMode.FILL); if (DEBUG) { System.out.println("Adding to 3D scene"); } root3d.getChildren().clear(); root3d.getChildren().add(meshView); if (DEBUG) { System.out.println("3D model is ready!"); } } The Imporeter3D class part: private void load(File file) { stlLoader = new STLLoader(file); } public float[] getCoords() { return stlLoader.getCoords(); } public float[] getTexCoords() { return stlLoader.getTexCoords(); } public int[] getFaces() { return stlLoader.getFaces(); } The STLLoader: public class STLLoader{ public STLLoader(File file) { stlFile = new STLFile(file); loadManager = stlFile.loadManager; pointsArray = new PointsArray(stlFile); texCoordsArray = new TexCoordsArray(); } public float[] getCoords() { return pointsArray.getPoints(); } public float[] getTexCoords() { return texCoordsArray.getTexCoords(); } public int[] getFaces() { return pointsArray.getFaces(); } private STLFile stlFile; private PointsArray pointsArray; private TexCoordsArray texCoordsArray; private FacesArray facesArray; public SimpleBooleanProperty finished = new SimpleBooleanProperty(false); public LoadManager loadManager;} PointsArray file: public class PointsArray { public PointsArray(STLFile stlFile) { this.stlFile = stlFile; initPoints(); } private void initPoints() { ArrayList<Double> pointsList = stlFile.getPoints(); ArrayList<Double> uPointsList = new ArrayList<>(); faces = new int[pointsList.size()*2]; int n = 0; for (Double d : pointsList) { if (uPointsList.indexOf(d) == -1) { uPointsList.add(d); } faces[n] = uPointsList.indexOf(d); faces[++n] = 0; n++; } int i = 0; points = new float[uPointsList.size()]; for (Double d : uPointsList) { points[i] = d.floatValue(); i++; } } public float[] getPoints() { return points; } public int[] getFaces() { return faces; } private float[] points; private int[] faces; private STLFile stlFile; public static boolean DEBUG = true; } And STLFile: ArrayList<Double> coords = new ArrayList<>(); double temp; private void readV(STLParser parser) { for (int n = 0; n < 3; n++) { if(!(parser.ttype==STLParser.TT_WORD && parser.sval.equals("vertex"))) { System.err.println("Format Error:expecting 'vertex' on line " + parser.lineno()); } else { if (parser.getNumber()) { temp = parser.nval; coords.add(temp); if(DEBUG) { System.out.println("Vertex:"); System.out.print("X=" + temp + " "); } if (parser.getNumber()) { temp = parser.nval; coords.add(temp); if(DEBUG) { System.out.print("Y=" + temp + " "); } if (parser.getNumber()) { temp = parser.nval; coords.add(temp); if(DEBUG) { System.out.println("Z=" + temp + " "); } readEOL(parser); } else System.err.println("Format Error: expecting coordinate on line " + parser.lineno()); } else System.err.println("Format Error: expecting coordinate on line " + parser.lineno()); } else System.err.println("Format Error: expecting coordinate on line " + parser.lineno()); } if (n < 2) { try { parser.nextToken(); } catch (IOException e) { System.err.println("IO Error on line " + parser.lineno() + ": " + e.getMessage()); } } } } public ArrayList<Double> getPoints() { return coords; } As a result of all of this code, I expected to get 3d model in MeshView. But the present result is very strange: everything works and in DEBUG mode I get 3d model is ready! from setContent(), and then unexpected ArrayIndexOutOfBoundsException: File readed Initialization of Mesh's arrays Applying Mesh's arrays Initialization of the material Setting the MeshView Adding to 3D scene 3D model is ready! java.lang.ArrayIndexOutOfBoundsException: Array index out of range: 32252 at com.sun.javafx.collections.ObservableFloatArrayImpl.rangeCheck(ObservableFloatArrayImpl.java:276) at com.sun.javafx.collections.ObservableFloatArrayImpl.get(ObservableFloatArrayImpl.java:184) at javafx.scene.shape.TriangleMesh.computeBounds(TriangleMesh.java:262) at javafx.scene.shape.MeshView.impl_computeGeomBounds(MeshView.java:151) at javafx.scene.Node.updateGeomBounds(Node.java:3497) at javafx.scene.Node.getGeomBounds(Node.java:3450) at javafx.scene.Node.getLocalBounds(Node.java:3432) at javafx.scene.Node.updateTxBounds(Node.java:3510) at javafx.scene.Node.getTransformedBounds(Node.java:3350) at javafx.scene.Node.updateBounds(Node.java:516) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.SubScene.updateBounds(SubScene.java:556) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:2309) at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:329) at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:479) at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:459) at com.sun.javafx.tk.quantum.QuantumToolkit$13.run(QuantumToolkit.java:326) at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95) at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) at com.sun.glass.ui.win.WinApplication.access$300(WinApplication.java:39) at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:101) at java.lang.Thread.run(Thread.java:724) Exception in thread "JavaFX Application Thread" java.lang.ArrayIndexOutOfBoundsException: Array index out of range: 32252 at com.sun.javafx.collections.ObservableFloatArrayImpl.rangeCheck(ObservableFloatArrayImpl.java:276) at com.sun.javafx.collections.ObservableFloatArrayImpl.get(ObservableFloatArrayImpl.java:184) The stranger thing is that this stack doesn't stop until I close the program. And moreover it doesn't point to any my array. What is this? And why does it happen?

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  • IBM PS/2 Keyboard with OS X 10.6 and PS2->USB Converter

    - by public static void
    Just got a new Mac Pro at work and as I can't stand the ZX Spectrum-esque 'dead flies' feel of the new Apple keyboards, I brought my trusty IBM SpaceSaver II to the office (with a USB/PS2 adapter) All seems generally to work ok - even the Trackpoint 'nipple' but periodically the modifier keys, notably the Ctrl and Windows keys seem to go into 'sticky' mode so that typing an 'S' brings up the save dialog, 'O' = open dialog etc. etc. Its generally fixed by switching windows and then returning back to the offending one, but this is really beginning to cheese me off. Can anyone suggest a fix?

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  • Using LINQ Distinct: With an Example on ASP.NET MVC SelectListItem

    - by Joe Mayo
    One of the things that might be surprising in the LINQ Distinct standard query operator is that it doesn’t automatically work properly on custom classes. There are reasons for this, which I’ll explain shortly. The example I’ll use in this post focuses on pulling a unique list of names to load into a drop-down list. I’ll explain the sample application, show you typical first shot at Distinct, explain why it won’t work as you expect, and then demonstrate a solution to make Distinct work with any custom class. The technologies I’m using are  LINQ to Twitter, LINQ to Objects, Telerik Extensions for ASP.NET MVC, ASP.NET MVC 2, and Visual Studio 2010. The function of the example program is to show a list of people that I follow.  In Twitter API vernacular, these people are called “Friends”; though I’ve never met most of them in real life. This is part of the ubiquitous language of social networking, and Twitter in particular, so you’ll see my objects named accordingly. Where Distinct comes into play is because I want to have a drop-down list with the names of the friends appearing in the list. Some friends are quite verbose, which means I can’t just extract names from each tweet and populate the drop-down; otherwise, I would end up with many duplicate names. Therefore, Distinct is the appropriate operator to eliminate the extra entries from my friends who tend to be enthusiastic tweeters. The sample doesn’t do anything with the drop-down list and I leave that up to imagination for what it’s practical purpose could be; perhaps a filter for the list if I only want to see a certain person’s tweets or maybe a quick list that I plan to combine with a TextBox and Button to reply to a friend. When the program runs, you’ll need to authenticate with Twitter, because I’m using OAuth (DotNetOpenAuth), for authentication, and then you’ll see the drop-down list of names above the grid with the most recent tweets from friends. Here’s what the application looks like when it runs: As you can see, there is a drop-down list above the grid. The drop-down list is where most of the focus of this article will be. There is some description of the code before we talk about the Distinct operator, but we’ll get there soon. This is an ASP.NET MVC2 application, written with VS 2010. Here’s the View that produces this screen: <%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<TwitterFriendsViewModel>" %> <%@ Import Namespace="DistinctSelectList.Models" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">     Home Page </asp:Content><asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">     <fieldset>         <legend>Twitter Friends</legend>         <div>             <%= Html.DropDownListFor(                     twendVM => twendVM.FriendNames,                     Model.FriendNames,                     "<All Friends>") %>         </div>         <div>             <% Html.Telerik().Grid<TweetViewModel>(Model.Tweets)                    .Name("TwitterFriendsGrid")                    .Columns(cols =>                     {                         cols.Template(col =>                             { %>                                 <img src="<%= col.ImageUrl %>"                                      alt="<%= col.ScreenName %>" />                         <% });                         cols.Bound(col => col.ScreenName);                         cols.Bound(col => col.Tweet);                     })                    .Render(); %>         </div>     </fieldset> </asp:Content> As shown above, the Grid is from Telerik’s Extensions for ASP.NET MVC. The first column is a template that renders the user’s Avatar from a URL provided by the Twitter query. Both the Grid and DropDownListFor display properties that are collections from a TwitterFriendsViewModel class, shown below: using System.Collections.Generic; using System.Web.Mvc; namespace DistinctSelectList.Models { /// /// For finding friend info on screen /// public class TwitterFriendsViewModel { /// /// Display names of friends in drop-down list /// public List FriendNames { get; set; } /// /// Display tweets in grid /// public List Tweets { get; set; } } } I created the TwitterFreindsViewModel. The two Lists are what the View consumes to populate the DropDownListFor and Grid. Notice that FriendNames is a List of SelectListItem, which is an MVC class. Another custom class I created is the TweetViewModel (the type of the Tweets List), shown below: namespace DistinctSelectList.Models { /// /// Info on friend tweets /// public class TweetViewModel { /// /// User's avatar /// public string ImageUrl { get; set; } /// /// User's Twitter name /// public string ScreenName { get; set; } /// /// Text containing user's tweet /// public string Tweet { get; set; } } } The initial Twitter query returns much more information than we need for our purposes and this a special class for displaying info in the View.  Now you know about the View and how it’s constructed. Let’s look at the controller next. The controller for this demo performs authentication, data retrieval, data manipulation, and view selection. I’ll skip the description of the authentication because it’s a normal part of using OAuth with LINQ to Twitter. Instead, we’ll drill down and focus on the Distinct operator. However, I’ll show you the entire controller, below,  so that you can see how it all fits together: using System.Linq; using System.Web.Mvc; using DistinctSelectList.Models; using LinqToTwitter; namespace DistinctSelectList.Controllers { [HandleError] public class HomeController : Controller { private MvcOAuthAuthorization auth; private TwitterContext twitterCtx; /// /// Display a list of friends current tweets /// /// public ActionResult Index() { auth = new MvcOAuthAuthorization(InMemoryTokenManager.Instance, InMemoryTokenManager.AccessToken); string accessToken = auth.CompleteAuthorize(); if (accessToken != null) { InMemoryTokenManager.AccessToken = accessToken; } if (auth.CachedCredentialsAvailable) { auth.SignOn(); } else { return auth.BeginAuthorize(); } twitterCtx = new TwitterContext(auth); var friendTweets = (from tweet in twitterCtx.Status where tweet.Type == StatusType.Friends select new TweetViewModel { ImageUrl = tweet.User.ProfileImageUrl, ScreenName = tweet.User.Identifier.ScreenName, Tweet = tweet.Text }) .ToList(); var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct() .ToList(); var twendsVM = new TwitterFriendsViewModel { Tweets = friendTweets, FriendNames = friendNames }; return View(twendsVM); } public ActionResult About() { return View(); } } } The important part of the listing above are the LINQ to Twitter queries for friendTweets and friendNames. Both of these results are used in the subsequent population of the twendsVM instance that is passed to the view. Let’s dissect these two statements for clarification and focus on what is happening with Distinct. The query for friendTweets gets a list of the 20 most recent tweets (as specified by the Twitter API for friend queries) and performs a projection into the custom TweetViewModel class, repeated below for your convenience: var friendTweets = (from tweet in twitterCtx.Status where tweet.Type == StatusType.Friends select new TweetViewModel { ImageUrl = tweet.User.ProfileImageUrl, ScreenName = tweet.User.Identifier.ScreenName, Tweet = tweet.Text }) .ToList(); The LINQ to Twitter query above simplifies what we need to work with in the View and the reduces the amount of information we have to look at in subsequent queries. Given the friendTweets above, the next query performs another projection into an MVC SelectListItem, which is required for binding to the DropDownList.  This brings us to the focus of this blog post, writing a correct query that uses the Distinct operator. The query below uses LINQ to Objects, querying the friendTweets collection to get friendNames: var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct() .ToList(); The above implementation of Distinct seems normal, but it is deceptively incorrect. After running the query above, by executing the application, you’ll notice that the drop-down list contains many duplicates.  This will send you back to the code scratching your head, but there’s a reason why this happens. To understand the problem, we must examine how Distinct works in LINQ to Objects. Distinct has two overloads: one without parameters, as shown above, and another that takes a parameter of type IEqualityComparer<T>.  In the case above, no parameters, Distinct will call EqualityComparer<T>.Default behind the scenes to make comparisons as it iterates through the list. You don’t have problems with the built-in types, such as string, int, DateTime, etc, because they all implement IEquatable<T>. However, many .NET Framework classes, such as SelectListItem, don’t implement IEquatable<T>. So, what happens is that EqualityComparer<T>.Default results in a call to Object.Equals, which performs reference equality on reference type objects.  You don’t have this problem with value types because the default implementation of Object.Equals is bitwise equality. However, most of your projections that use Distinct are on classes, just like the SelectListItem used in this demo application. So, the reason why Distinct didn’t produce the results we wanted was because we used a type that doesn’t define its own equality and Distinct used the default reference equality. This resulted in all objects being included in the results because they are all separate instances in memory with unique references. As you might have guessed, the solution to the problem is to use the second overload of Distinct that accepts an IEqualityComparer<T> instance. If you were projecting into your own custom type, you could make that type implement IEqualityComparer<T>, but SelectListItem belongs to the .NET Framework Class Library.  Therefore, the solution is to create a custom type to implement IEqualityComparer<T>, as in the SelectListItemComparer class, shown below: using System.Collections.Generic; using System.Web.Mvc; namespace DistinctSelectList.Models { public class SelectListItemComparer : EqualityComparer { public override bool Equals(SelectListItem x, SelectListItem y) { return x.Value.Equals(y.Value); } public override int GetHashCode(SelectListItem obj) { return obj.Value.GetHashCode(); } } } The SelectListItemComparer class above doesn’t implement IEqualityComparer<SelectListItem>, but rather derives from EqualityComparer<SelectListItem>. Microsoft recommends this approach for consistency with the behavior of generic collection classes. However, if your custom type already derives from a base class, go ahead and implement IEqualityComparer<T>, which will still work. EqualityComparer is an abstract class, that implements IEqualityComparer<T> with Equals and GetHashCode abstract methods. For the purposes of this application, the SelectListItem.Value property is sufficient to determine if two items are equal.   Since SelectListItem.Value is type string, the code delegates equality to the string class. The code also delegates the GetHashCode operation to the string class.You might have other criteria in your own object and would need to define what it means for your object to be equal. Now that we have an IEqualityComparer<SelectListItem>, let’s fix the problem. The code below modifies the query where we want distinct values: var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct(new SelectListItemComparer()) .ToList(); Notice how the code above passes a new instance of SelectListItemComparer as the parameter to the Distinct operator. Now, when you run the application, the drop-down list will behave as you expect, showing only a unique set of names. In addition to Distinct, other LINQ Standard Query Operators have overloads that accept IEqualityComparer<T>’s, You can use the same techniques as shown here, with SelectListItemComparer, with those other operators as well. Now you know how to resolve problems with getting Distinct to work properly and also have a way to fix problems with other operators that require equality comparisons. @JoeMayo

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  • C#/.NET Little Wonders: The EventHandler and EventHandler&lt;TEventArgs&gt; delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the last two weeks, we examined the Action family of delegates (and delegates in general), and the Func family of delegates and how they can be used to support generic, reusable algorithms and classes. So this week, we are going to look at a handy pair of delegates that can be used to eliminate the need for defining custom delegates when creating events: the EventHandler and EventHandler<TEventArgs> delegates. Events and delegates Before we begin, let’s quickly consider events in .NET.  According to the MSDN: An event in C# is a way for a class to provide notifications to clients of that class when some interesting thing happens to an object. So, basically, you can create an event in a type so that users of that type can subscribe to notifications of things of interest.  How is this different than some of the delegate programming that we talked about in the last two weeks?  Well, you can think of an event as a special access modifier on a delegate.  Some differences between the two are: Events are a special access case of delegates They behave much like delegates instances inside the type they are declared in, but outside of that type they can only be (un)subscribed to. Events can specify add/remove behavior explicitly If you want to do additional work when someone subscribes or unsubscribes to an event, you can specify the add and remove actions explicitly. Events have access modifiers, but these only specify the access level of those who can (un)subscribe A public event, for example, means anyone can (un)subscribe, but it does not mean that anyone can raise (invoke) the event directly.  Events can only be raised by the type that contains them In contrast, if a delegate is visible, it can be invoked outside of the object (not even in a sub-class!). Events tend to be for notifications only, and should be treated as optional Semantically speaking, events typically don’t perform work on the the class directly, but tend to just notify subscribers when something of note occurs. My basic rule-of-thumb is that if you are just wanting to notify any listeners (who may or may not care) that something has happened, use an event.  However, if you want the caller to provide some function to perform to direct the class about how it should perform work, make it a delegate. Declaring events using custom delegates To declare an event in a type, we simply use the event keyword and specify its delegate type.  For example, let’s say you wanted to create a new TimeOfDayTimer that triggers at a given time of the day (as opposed to on an interval).  We could write something like this: 1: public delegate void TimeOfDayHandler(object source, ElapsedEventArgs e); 2:  3: // A timer that will fire at time of day each day. 4: public class TimeOfDayTimer : IDisposable 5: { 6: // Event that is triggered at time of day. 7: public event TimeOfDayHandler Elapsed; 8:  9: // ... 10: } The first thing to note is that the event is a delegate type, which tells us what types of methods may subscribe to it.  The second thing to note is the signature of the event handler delegate, according to the MSDN: The standard signature of an event handler delegate defines a method that does not return a value, whose first parameter is of type Object and refers to the instance that raises the event, and whose second parameter is derived from type EventArgs and holds the event data. If the event does not generate event data, the second parameter is simply an instance of EventArgs. Otherwise, the second parameter is a custom type derived from EventArgs and supplies any fields or properties needed to hold the event data. So, in a nutshell, the event handler delegates should return void and take two parameters: An object reference to the object that raised the event. An EventArgs (or a subclass of EventArgs) reference to event specific information. Even if your event has no additional information to provide, you are still expected to provide an EventArgs instance.  In this case, feel free to pass the EventArgs.Empty singleton instead of creating new instances of EventArgs (to avoid generating unneeded memory garbage). The EventHandler delegate Because many events have no additional information to pass, and thus do not require custom EventArgs, the signature of the delegates for subscribing to these events is typically: 1: // always takes an object and an EventArgs reference 2: public delegate void EventHandler(object sender, EventArgs e) It would be insane to recreate this delegate for every class that had a basic event with no additional event data, so there already exists a delegate for you called EventHandler that has this very definition!  Feel free to use it to define any events which supply no additional event information: 1: public class Cache 2: { 3: // event that is raised whenever the cache performs a cleanup 4: public event EventHandler OnCleanup; 5:  6: // ... 7: } This will handle any event with the standard EventArgs (no additional information).  But what of events that do need to supply additional information?  Does that mean we’re out of luck for subclasses of EventArgs?  That’s where the generic for of EventHandler comes into play… The generic EventHandler<TEventArgs> delegate Starting with the introduction of generics in .NET 2.0, we have a generic delegate called EventHandler<TEventArgs>.  Its signature is as follows: 1: public delegate void EventHandler<TEventArgs>(object sender, TEventArgs e) 2: where TEventArgs : EventArgs This is similar to EventHandler except it has been made generic to support the more general case.  Thus, it will work for any delegate where the first argument is an object (the sender) and the second argument is a class derived from EventArgs (the event data). For example, let’s say we wanted to create a message receiver, and we wanted it to have a few events such as OnConnected that will tell us when a connection is established (probably with no additional information) and OnMessageReceived that will tell us when a new message arrives (probably with a string for the new message text). So for OnMessageReceived, our MessageReceivedEventArgs might look like this: 1: public sealed class MessageReceivedEventArgs : EventArgs 2: { 3: public string Message { get; set; } 4: } And since OnConnected needs no event argument type defined, our class might look something like this: 1: public class MessageReceiver 2: { 3: // event that is called when the receiver connects with sender 4: public event EventHandler OnConnected; 5:  6: // event that is called when a new message is received. 7: public event EventHandler<MessageReceivedEventArgs> OnMessageReceived; 8:  9: // ... 10: } Notice, nowhere did we have to define a delegate to fit our event definition, the EventHandler and generic EventHandler<TEventArgs> delegates fit almost anything we’d need to do with events. Sidebar: Thread-safety and raising an event When the time comes to raise an event, we should always check to make sure there are subscribers, and then only raise the event if anyone is subscribed.  This is important because if no one is subscribed to the event, then the instance will be null and we will get a NullReferenceException if we attempt to raise the event. 1: // This protects against NullReferenceException... or does it? 2: if (OnMessageReceived != null) 3: { 4: OnMessageReceived(this, new MessageReceivedEventArgs(aMessage)); 5: } The above code seems to handle the null reference if no one is subscribed, but there’s a problem if this is being used in multi-threaded environments.  For example, assume we have thread A which is about to raise the event, and it checks and clears the null check and is about to raise the event.  However, before it can do that thread B unsubscribes to the event, which sets the delegate to null.  Now, when thread A attempts to raise the event, this causes the NullReferenceException that we were hoping to avoid! To counter this, the simplest best-practice method is to copy the event (just a multicast delegate) to a temporary local variable just before we raise it.  Since we are inside the class where this event is being raised, we can copy it to a local variable like this, and it will protect us from multi-threading since multicast delegates are immutable and assignments are atomic: 1: // always make copy of the event multi-cast delegate before checking 2: // for null to avoid race-condition between the null-check and raising it. 3: var handler = OnMessageReceived; 4: 5: if (handler != null) 6: { 7: handler(this, new MessageReceivedEventArgs(aMessage)); 8: } The very slight trade-off is that it’s possible a class may get an event after it unsubscribes in a multi-threaded environment, but this is a small risk and classes should be prepared for this possibility anyway.  For a more detailed discussion on this, check out this excellent Eric Lippert blog post on Events and Races. Summary Generic delegates give us a lot of power to make generic algorithms and classes, and the EventHandler delegate family gives us the flexibility to create events easily, without needing to redefine delegates over and over.  Use them whenever you need to define events with or without specialized EventArgs.   Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Delegates, EventHandler

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  • Looking into Entity Framework Code First Migrations

    - by nikolaosk
    In this post I will introduce you to Code First Migrations, an Entity Framework feature introduced in version 4.3 back in February of 2012.I have extensively covered Entity Framework in this blog. Please find my other Entity Framework posts here .   Before the addition of Code First Migrations (4.1,4.2 versions), Code First database initialisation meant that Code First would create the database if it does not exist (the default behaviour - CreateDatabaseIfNotExists). The other pattern we could use is DropCreateDatabaseIfModelChanges which means that Entity Framework, will drop the database if it realises that model has changes since the last time it created the database.The final pattern is DropCreateDatabaseAlways which means that Code First will recreate the database every time one runs the application.That is of course fine for the development database but totally unacceptable and catastrophic when you have a production database. We cannot lose our data because of the work that Code First works.Migrations solve this problem.With migrations we can modify the database without completely dropping it.We can modify the database schema to reflect the changes to the model without losing data.In version EF 5.0 migrations are fully included and supported. I will demonstrate migrations with a hands-on example.Let me say a few words first about Entity Framework first. The .Net framework provides support for Object Relational Mappingthrough EF. So EF is a an ORM tool and it is now the main data access technology that microsoft works on. I use it quite extensively in my projects. Through EF we have many things out of the box provided for us. We have the automatic generation of SQL code.It maps relational data to strongly types objects.All the changes made to the objects in the memory are persisted in a transactional way back to the data store. You can find in this post an example on how to use the Entity Framework to retrieve data from an SQL Server Database using the "Database/Schema First" approach.In this approach we make all the changes at the database level and then we update the model with those changes. In this post you can see an example on how to use the "Model First" approach when working with ASP.Net and the Entity Framework.This model was firstly introduced in EF version 4.0 and we could start with a blank model and then create a database from that model.When we made changes to the model , we could recreate the database from the new model. The Code First approach is the more code-centric than the other two. Basically we write POCO classes and then we persist to a database using something called DBContext.Code First relies on DbContext. We create 2,3 classes (e.g Person,Product) with properties and then these classes interact with the DbContext class we can create a new database based upon our POCOS classes and have tables generated from those classes.We do not have an .edmx file in this approach.By using this approach we can write much easier unit tests.DbContext is a new context class and is smaller,lightweight wrapper for the main context class which is ObjectContext (Schema First and Model First).Let's move on to our hands-on example.I have installed VS 2012 Ultimate edition in my Windows 8 machine. 1)  Create an empty asp.net web application. Give your application a suitable name. Choose C# as the development language2) Add a new web form item in your application. Leave the default name.3) Create a new folder. Name it CodeFirst .4) Add a new item in your application, a class file. Name it Footballer.cs. This is going to be a simple POCO class.Place this class file in the CodeFirst folder.The code follows    public class Footballer     {         public int FootballerID { get; set; }         public string FirstName { get; set; }         public string LastName { get; set; }         public double Weight { get; set; }         public double Height { get; set; }              }5) We will have to add EF 5.0 to our project. Right-click on the project in the Solution Explorer and select Manage NuGet Packages... for it.In the window that will pop up search for Entity Framework and install it.Have a look at the picture below   If you want to find out if indeed EF version is 5.0 version is installed have a look at the References. Have a look at the picture below to see what you will see if you have installed everything correctly.Have a look at the picture below 6) Then we need to create a context class that inherits from DbContext.Add a new class to the CodeFirst folder.Name it FootballerDBContext.Now that we have the entity classes created, we must let the model know.I will have to use the DbSet<T> property.The code for this class follows     public class FootballerDBContext:DbContext     {         public DbSet<Footballer> Footballers { get; set; }             }    Do not forget to add  (using System.Data.Entity;) in the beginning of the class file 7) We must take care of the connection string. It is very easy to create one in the web.config.It does not matter that we do not have a database yet.When we run the DbContext and query against it , it will use a connection string in the web.config and will create the database based on the classes.I will use the name "FootballTraining" for the database.In my case the connection string inside the web.config, looks like this    <connectionStrings>    <add name="CodeFirstDBContext" connectionString="server=.;integrated security=true; database=FootballTraining" providerName="System.Data.SqlClient"/>                       </connectionStrings>8) Now it is time to create Linq to Entities queries to retrieve data from the database . Add a new class to your application in the CodeFirst folder.Name the file DALfootballer.csWe will create a simple public method to retrieve the footballers. The code for the class followspublic class DALfootballer     {         FootballerDBContext ctx = new FootballerDBContext();         public List<Footballer> GetFootballers()         {             var query = from player in ctx.Footballers select player;             return query.ToList();         }     } 9) Place a GridView control on the Default.aspx page and leave the default name.Add an ObjectDataSource control on the Default.aspx page and leave the default name. Set the DatasourceID property of the GridView control to the ID of the ObjectDataSource control.(DataSourceID="ObjectDataSource1" ). Let's configure the ObjectDataSource control. Click on the smart tag item of the ObjectDataSource control and select Configure Data Source. In the Wizzard that pops up select the DALFootballer class and then in the next step choose the GetFootballers() method.Click Finish to complete the steps of the wizzard.Build and Run your application.  10) Obviously you will not see any records coming back from your database, because we have not inserted anything. The database is created, though.Have a look at the picture below.  11) Now let's change the POCO class. Let's add a new property to the Footballer.cs class.        public int Age { get; set; } Build and run your application again. You will receive an error. Have a look at the picture below 12) That was to be expected.EF Code First Migrations is not activated by default. We have to activate them manually and configure them according to your needs. We will open the Package Manager Console from the Tools menu within Visual Studio 2012.Then we will activate the EF Code First Migration Features by writing the command “Enable-Migrations”.  Have a look at the picture below. This adds a new folder Migrations in our project. A new auto-generated class Configuration.cs is created.Another class is also created [CURRENTDATE]_InitialCreate.cs and added to our project.The Configuration.cs  is shown in the picture below. The [CURRENTDATE]_InitialCreate.cs is shown in the picture below  13) ??w we are ready to migrate the changes in the database. We need to run the Add-Migration Age command in Package Manager ConsoleAdd-Migration will scaffold the next migration based on changes you have made to your model since the last migration was created.In the Migrations folder, the file 201211201231066_Age.cs is created.Have a look at the picture below to see the newly generated file and its contents. Now we can run the Update-Database command in Package Manager Console .See the picture above.Code First Migrations will compare the migrations in our Migrations folder with the ones that have been applied to the database. It will see that the Age migration needs to be applied, and run it.The EFMigrations.CodeFirst.FootballeDBContext database is now updated to include the Age column in the Footballers table.Build and run your application.Everything will work fine now.Have a look at the picture below to see the migrations applied to our table. 14) We may want it to automatically upgrade the database (by applying any pending migrations) when the application launches.Let's add another property to our Poco class.          public string TShirtNo { get; set; }We want this change to migrate automatically to the database.We go to the Configuration.cs we enable automatic migrations.     public Configuration()        {            AutomaticMigrationsEnabled = true;        } In the Page_Load event handling routine we have to register the MigrateDatabaseToLatestVersion database initializer. A database initializer simply contains some logic that is used to make sure the database is setup correctly.   protected void Page_Load(object sender, EventArgs e)        {            Database.SetInitializer(new MigrateDatabaseToLatestVersion<FootballerDBContext, Configuration>());        } Build and run your application. It will work fine. Have a look at the picture below to see the migrations applied to our table in the database. Hope it helps!!!  

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  • C#: Handling Notifications: inheritance, events, or delegates?

    - by James Michael Hare
    Often times as developers we have to design a class where we get notification when certain things happen. In older object-oriented code this would often be implemented by overriding methods -- with events, delegates, and interfaces, however, we have far more elegant options. So, when should you use each of these methods and what are their strengths and weaknesses? Now, for the purposes of this article when I say notification, I'm just talking about ways for a class to let a user know that something has occurred. This can be through any programmatic means such as inheritance, events, delegates, etc. So let's build some context. I'm sitting here thinking about a provider neutral messaging layer for the place I work, and I got to the point where I needed to design the message subscriber which will receive messages from the message bus. Basically, what we want is to be able to create a message listener and have it be called whenever a new message arrives. Now, back before the flood we would have done this via inheritance and an abstract class: 1:  2: // using inheritance - omitting argument null checks and halt logic 3: public abstract class MessageListener 4: { 5: private ISubscriber _subscriber; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber) 11: { 12: _subscriber = subscriber; 13: _messageThread = new Thread(MessageLoop); 14: _messageThread.Start(); 15: } 16:  17: // user will override this to process their messages 18: protected abstract void OnMessageReceived(Message msg); 19:  20: // handle the looping in the thread 21: private void MessageLoop() 22: { 23: while(!_isHalted) 24: { 25: // as long as processing, wait 1 second for message 26: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 27: if(msg != null) 28: { 29: OnMessageReceived(msg); 30: } 31: } 32: } 33: ... 34: } It seems so odd to write this kind of code now. Does it feel odd to you? Maybe it's just because I've gotten so used to delegation that I really don't like the feel of this. To me it is akin to saying that if I want to drive my car I need to derive a new instance of it just to put myself in the driver's seat. And yet, unquestionably, five years ago I would have probably written the code as you see above. To me, inheritance is a flawed approach for notifications due to several reasons: Inheritance is one of the HIGHEST forms of coupling. You can't seal the listener class because it depends on sub-classing to work. Because C# does not allow multiple-inheritance, I've spent my one inheritance implementing this class. Every time you need to listen to a bus, you have to derive a class which leads to lots of trivial sub-classes. The act of consuming a message should be a separate responsibility than the act of listening for a message (SRP). Inheritance is such a strong statement (this IS-A that) that it should only be used in building type hierarchies and not for overriding use-specific behaviors and notifications. Chances are, if a class needs to be inherited to be used, it most likely is not designed as well as it could be in today's modern programming languages. So lets look at the other tools available to us for getting notified instead. Here's a few other choices to consider. Have the listener expose a MessageReceived event. Have the listener accept a new IMessageHandler interface instance. Have the listener accept an Action<Message> delegate. Really, all of these are different forms of delegation. Now, .NET events are a bit heavier than the other types of delegates in terms of run-time execution, but they are a great way to allow others using your class to subscribe to your events: 1: // using event - ommiting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private bool _isHalted = false; 6: private Thread _messageThread; 7:  8: // assign the subscriber and start the messaging loop 9: public MessageListener(ISubscriber subscriber) 10: { 11: _subscriber = subscriber; 12: _messageThread = new Thread(MessageLoop); 13: _messageThread.Start(); 14: } 15:  16: // user will override this to process their messages 17: public event Action<Message> MessageReceived; 18:  19: // handle the looping in the thread 20: private void MessageLoop() 21: { 22: while(!_isHalted) 23: { 24: // as long as processing, wait 1 second for message 25: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 26: if(msg != null && MessageReceived != null) 27: { 28: MessageReceived(msg); 29: } 30: } 31: } 32: } Note, now we can seal the class to avoid changes and the user just needs to provide a message handling method: 1: theListener.MessageReceived += CustomReceiveMethod; However, personally I don't think events hold up as well in this case because events are largely optional. To me, what is the point of a listener if you create one with no event listeners? So in my mind, use events when handling the notification is optional. So how about the delegation via interface? I personally like this method quite a bit. Basically what it does is similar to inheritance method mentioned first, but better because it makes it easy to split the part of the class that doesn't change (the base listener behavior) from the part that does change (the user-specified action after receiving a message). So assuming we had an interface like: 1: public interface IMessageHandler 2: { 3: void OnMessageReceived(Message receivedMessage); 4: } Our listener would look like this: 1: // using delegation via interface - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private IMessageHandler _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler.OnMessageReceived(msg); 28: } 29: } 30: } 31: } And they would call it by creating a class that implements IMessageHandler and pass that instance into the constructor of the listener. I like that this alleviates the issues of inheritance and essentially forces you to provide a handler (as opposed to events) on construction. Well, this is good, but personally I think we could go one step further. While I like this better than events or inheritance, it still forces you to implement a specific method name. What if that name collides? Furthermore if you have lots of these you end up either with large classes inheriting multiple interfaces to implement one method, or lots of small classes. Also, if you had one class that wanted to manage messages from two different subscribers differently, it wouldn't be able to because the interface can't be overloaded. This brings me to using delegates directly. In general, every time I think about creating an interface for something, and if that interface contains only one method, I start thinking a delegate is a better approach. Now, that said delegates don't accomplish everything an interface can. Obviously having the interface allows you to refer to the classes that implement the interface which can be very handy. In this case, though, really all you want is a method to handle the messages. So let's look at a method delegate: 1: // using delegation via delegate - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler(msg); 28: } 29: } 30: } 31: } Here the MessageListener now takes an Action<Message>.  For those of you unfamiliar with the pre-defined delegate types in .NET, that is a method with the signature: void SomeMethodName(Message). The great thing about delegates is it gives you a lot of power. You could create an anonymous delegate, a lambda, or specify any other method as long as it satisfies the Action<Message> signature. This way, you don't need to define an arbitrary helper class or name the method a specific thing. Incidentally, we could combine both the interface and delegate approach to allow maximum flexibility. Doing this, the user could either pass in a delegate, or specify a delegate interface: 1: // using delegation - give users choice of interface or delegate 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // passes the interface method as a delegate using method group 19: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 20: : this(subscriber, handler.OnMessageReceived) 21: { 22: } 23:  24: // handle the looping in the thread 25: private void MessageLoop() 26: { 27: while(!_isHalted) 28: { 29: // as long as processing, wait 1 second for message 30: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 31: if(msg != null) 32: { 33: _handler(msg); 34: } 35: } 36: } 37: } } This is the method I tend to prefer because it allows the user of the class to choose which method works best for them. You may be curious about the actual performance of these different methods. 1: Enter iterations: 2: 1000000 3:  4: Inheritance took 4 ms. 5: Events took 7 ms. 6: Interface delegation took 4 ms. 7: Lambda delegate took 5 ms. Before you get too caught up in the numbers, however, keep in mind that this is performance over over 1,000,000 iterations. Since they are all < 10 ms which boils down to fractions of a micro-second per iteration so really any of them are a fine choice performance wise. As such, I think the choice of what to do really boils down to what you're trying to do. Here's my guidelines: Inheritance should be used only when defining a collection of related types with implementation specific behaviors, it should not be used as a hook for users to add their own functionality. Events should be used when subscription is optional or multi-cast is desired. Interface delegation should be used when you wish to refer to implementing classes by the interface type or if the type requires several methods to be implemented. Delegate method delegation should be used when you only need to provide one method and do not need to refer to implementers by the interface name.

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  • Validation Summary for Lists using Data Annotations with MVC

    - by David Liddle
    I currently use a custom method to display validation error messages for lists but would like to replace this system for using with Data Annotations. In summary on validation of my form, I want to display "*" next to each input that is incorrect and also provide a Validation Summary at the bottom that relates each error message to the particular item in the list. e.g. say if validation failed on the 2nd list item on a Name input box and the 4th item on an Address input box the validation summary would display [2] Name is invalid [4] Address is invalid Please ignore if there are mistakes in the code below. I'm just writing this as an example. The code below shows how I was able to do it using my custom version of adding model errors but was wondering how to do this using Data Annotations? //Domain Object public class MyObject { public int ID { get; set; } public string Name { get; set; } public string Address { get; set; } public bool IsValid { get { return (GetRuleViolations().Count() == 0); } } public void IEnumerable<RuleViolation> GetRuleViolations() { if (String.IsNullOrEmpty(Name)) yield return new RuleViolation(ID, "Name", "Name is invalid"); if (String.IsNullOrEmpty(Address)) yield return new RuleViolation(ID, "Address", "Address is invalid"); yield break; } } //Rule Violation public class RuleViolation { public int ID { get; private set; } public string PropertyName { get; private set; } public string ErrorMessage { get; private set; } } //View <% for (int i = 0; i < 5; i++) { %> <p> <%= Html.Hidden("myObjects[" + i + "].ID", i) %> Name: <%= Html.TextBox("myObjects[" + i + "].Name") %> <br /> <%= Html.ValidationMessage("myObjects[" + i + "].Name", "*")<br /> Address: <%= Html.TextBox("myObjects[" + i + "].Address") %> <%= Html.ValidationMessage("myObjects[" + i + "].Address", "*")<br /> </p> <% } %> <p><%= Html.ValidationSummary() %> //Controller public ActionResult MyAction(IList<MyObject> myObjects) { foreach (MyObject o in myObjects) { if (!o.IsValid) ModelState.AddModelErrors(o.GetRuleViolations(), o.GetType().Name); } if (!Model.IsValid) { return View(); } } public static class ModelStateExtensions { public static void AddModelError(this ModelStateDictionary modelState, RuleViolation issue, string name) { string key = String.Format("{0}[{1}].{2}", name, issue.ID, issue.PropertyName); string error = String.Format("[{0}] {1}", (issue.ID + 1), issue.ErrorMessage); //above line determines the [ID] ErrorMessage to be //displayed in the Validation Summary modelState.AddModelError(key, error); }

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  • Rendering a random generated maze in WinForms.NET

    - by Claus Jørgensen
    Hi I'm trying to create a maze-generator, and for this I have implemented the Randomized Prim's Algorithm in C#. However, the result of the generation is invalid. I can't figure out if it's my rendering, or the implementation that's invalid. So for starters, I'd like to have someone take a look at the implementation: maze is a matrix of cells. var cell = maze[0, 0]; cell.Connected = true; var walls = new HashSet<MazeWall>(cell.Walls); while (walls.Count > 0) { var randomWall = walls.GetRandom(); var randomCell = randomWall.A.Connected ? randomWall.B : randomWall.A; if (!randomCell.Connected) { randomWall.IsPassage = true; randomCell.Connected = true; foreach (var wall in randomCell.Walls) walls.Add(wall); } walls.Remove(randomWall); } Here's a example on the rendered result: Edit Ok, lets have a look at the rendering part then: private void MazePanel_Paint(object sender, PaintEventArgs e) { int size = 20; int cellSize = 10; MazeCell[,] maze = RandomizedPrimsGenerator.Generate(size); mazePanel.Size = new Size( size * cellSize + 1, size * cellSize + 1 ); e.Graphics.DrawRectangle(Pens.Blue, 0, 0, size * cellSize, size * cellSize ); for (int y = 0; y < size; y++) for (int x = 0; x < size; x++) { foreach(var wall in maze[x, y].Walls.Where(w => !w.IsPassage)) { if (wall.Direction == MazeWallOrientation.Horisontal) { e.Graphics.DrawLine(Pens.Blue, x * cellSize, y * cellSize, x * cellSize + cellSize, y * cellSize ); } else { e.Graphics.DrawLine(Pens.Blue, x * cellSize, y * cellSize, x * cellSize, y * cellSize + cellSize ); } } } } And I guess, to understand this we need to see the MazeCell and MazeWall class: namespace MazeGenerator.Maze { class MazeCell { public int Column { get; set; } public int Row { get; set; } public bool Connected { get; set; } private List<MazeWall> walls = new List<MazeWall>(); public List<MazeWall> Walls { get { return walls; } set { walls = value; } } public MazeCell() { this.Connected = false; } public void AddWall(MazeCell b) { walls.Add(new MazeWall(this, b)); } } enum MazeWallOrientation { Horisontal, Vertical, Undefined } class MazeWall : IEquatable<MazeWall> { public IEnumerable<MazeCell> Cells { get { yield return CellA; yield return CellB; } } public MazeCell CellA { get; set; } public MazeCell CellB { get; set; } public bool IsPassage { get; set; } public MazeWallOrientation Direction { get { if (CellA.Column == CellB.Column) { return MazeWallOrientation.Horisontal; } else if (CellA.Row == CellB.Row) { return MazeWallOrientation.Vertical; } else { return MazeWallOrientation.Undefined; } } } public MazeWall(MazeCell a, MazeCell b) { this.CellA = a; this.CellB = b; a.Walls.Add(this); b.Walls.Add(this); IsPassage = false; } #region IEquatable<MazeWall> Members public bool Equals(MazeWall other) { return (this.CellA == other.CellA) && (this.CellB == other.CellB); } #endregion } }

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  • Game loop and time tracking

    - by David Brown
    Maybe I'm just an idiot, but I've been trying to implement a game loop all day and it's just not clicking. I've read literally every article I could find on Google, but the problem is that they all use different timing mechanisms, which makes them difficult to apply to my particular situation (some use milliseconds, other use ticks, etc). Basically, I have a Clock object that updates each time the game loop executes. internal class Clock { public static long Timestamp { get { return Stopwatch.GetTimestamp(); } } public static long Frequency { get { return Stopwatch.Frequency; } } private long _startTime; private long _lastTime; private TimeSpan _totalTime; private TimeSpan _elapsedTime; /// <summary> /// The amount of time that has passed since the first step. /// </summary> public TimeSpan TotalTime { get { return _totalTime; } } /// <summary> /// The amount of time that has passed since the last step. /// </summary> public TimeSpan ElapsedTime { get { return _elapsedTime; } } public Clock() { Reset(); } public void Reset() { _startTime = Timestamp; _lastTime = 0; _totalTime = TimeSpan.Zero; _elapsedTime = TimeSpan.Zero; } public void Tick() { long currentTime = Timestamp; if (_lastTime == 0) _lastTime = currentTime; _totalTime = TimestampToTimeSpan(currentTime - _startTime); _elapsedTime = TimestampToTimeSpan(currentTime - _lastTime); _lastTime = currentTime; } public static TimeSpan TimestampToTimeSpan(long timestamp) { return TimeSpan.FromTicks( (timestamp * TimeSpan.TicksPerSecond) / Frequency); } } I based most of that on the XNA GameClock, but it's greatly simplified. Then, I have a Time class which holds various times that the Update and Draw methods need to know. public class Time { public TimeSpan ElapsedVirtualTime { get; internal set; } public TimeSpan ElapsedRealTime { get; internal set; } public TimeSpan TotalVirtualTime { get; internal set; } public TimeSpan TotalRealTime { get; internal set; } internal Time() { } internal Time(TimeSpan elapsedVirtualTime, TimeSpan elapsedRealTime, TimeSpan totalVirutalTime, TimeSpan totalRealTime) { ElapsedVirtualTime = elapsedVirtualTime; ElapsedRealTime = elapsedRealTime; TotalVirtualTime = totalVirutalTime; TotalRealTime = totalRealTime; } } My main class keeps a single instance of Time, which it should constantly update during the game loop. So far, I have this: private static void Loop() { do { Clock.Tick(); Time.TotalRealTime = Clock.TotalTime; Time.ElapsedRealTime = Clock.ElapsedTime; InternalUpdate(Time); InternalDraw(Time); } while (!_exitRequested); } The real time properties of the time class turn out great. Now I'd like to get a proper update/draw loop working so that the state is updated a variable number of times per frame, but at a fixed timestep. At the same time, the Time.TotalVirtualTime and Time.ElapsedVirtualTime should be updated accordingly. In addition, I intend for this to support multiplayer in the future, in case that makes any difference to the design of the game loop. Any tips or examples on how I could go about implementing this (aside from links to articles)?

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  • WPF Tree doesn't work

    - by phenevo
    Could you tell me why I can't see subItems? I've got winforms apps and I added my wpfusercontrol:ObjectsAndZonesTree ServiceProvider is my webservice. Adn method to get listofcountires with subitems works properly (i get countires, regions from this countires, provinces etc...) ElementHost elementHost = new ElementHost { Width = 150, Height = 50, Dock = DockStyle.Fill, Child = new ObjectsAndZonesTree() }; this.splitContainer3.Panel1.Controls.Add(elementHost); XAML: <TreeView Name="GroupView" Grid.Row="0" Grid.Column="0" ItemsSource="{Binding}"> <TreeView.Resources> <HierarchicalDataTemplate DataType="{x:Type ServiceProvider:Country }" ItemsSource="{Binding Items}"> <TextBlock Text="{Binding Path=Name}" /> </HierarchicalDataTemplate> <DataTemplate DataType="{x:Type ServiceProvider:Region}" > <TextBlock Text="{Binding Path=Name}" /> </DataTemplate> <DataTemplate DataType="{x:Type ServiceProvider:Province}" > <TextBlock Text="{Binding Path=Name}" /> </DataTemplate> </TreeView.Resources> </TreeView> XAML.CS public ObjectsAndZonesTree() { InitializeComponent(); LoadView(); } private void LoadView() { GroupView.ItemsSource = new ServiceProvider().GetListOfObjectsAndZones(); } class Country: public class Country { string _name; [XmlAttribute] public string Name { get { return _name; } set { _name = value; } } string _code; [XmlAttribute] public string Code { get { return _code; } set { _code = value; } } string _continentCode; [XmlAttribute] public string ContinentCode { get { return _continentCode; } set { _continentCode = value; } } public Region[] ListOfRegions { get { return _listOfRegions; } set { _listOfRegions = value; } } private Region[] _listOfRegions; public IList<object> Items { get { IList<object> childNodes = new List<object>(); foreach (var group in this.ListOfRegions) childNodes.Add(group); return childNodes; } } } Class Region: public class Region { private Province[] _listOfProvinces; private string _name; private string _code; public Province[] ListOfProvinces { get { return _listOfProvinces; } set { _listOfProvinces = value; } } public string Name { get { return _name; } set { _name = value; } } public string Code { get { return _code; } set { _code = value; } } public string CountryCode { get { return _countryCode; } set { _countryCode = value; } } private string _countryCode; public IList<object> Items { get { IList<object> childNodes = new List<object>(); foreach (var group in this.ListOfProvinces) childNodes.Add(group); return childNodes; } } } It displays me only list of countires.

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  • Problem Registering a Generic Repository with Windsor IoC

    - by Robin
    I’m fairly new to IoC and perhaps my understanding of generics and inheritance is not strong enough for what I’m trying to do. You might find this to be a mess. I have a generic Repository base class: public class Repository<TEntity> where TEntity : class, IEntity { private Table<TEntity> EntityTable; private string _connectionString; private string _userName; public string UserName { get { return _userName; } set { _userName = value; } } public Repository() {} public Repository(string connectionString) { _connectionString = connectionString; EntityTable = (new DataContext(connectionString)).GetTable<TEntity>(); } public Repository(string connectionString, string userName) { _connectionString = connectionString; _userName = userName; EntityTable = (new DataContext(connectionString)).GetTable<TEntity>(); } // Data access methods ... ... } and a SqlClientRepository that inherits Repository: public class SqlClientRepository : Repository<Client> { private Table<Client> ClientTable; private string _connectionString; private string _userName; public SqlClientRepository() {} public SqlClientRepository(string connectionString) : base(connectionString) { _connectionString = connectionString; ClientTable = (new DataContext(connectionString)).GetTable<Client>(); } public SqlClientRepository(string connectionString, string userName) : base(connectionString, userName) { _connectionString = connectionString; _userName = userName; ClientTable = (new DataContext(connectionString)).GetTable<Client>(); } // data access methods unique to Client repository ... } The Repository class provides some generics methods like Save, Delete, etc, that I want all my repository derived classes to share. The TEntity parameter is constrained to the IEntity interface: public interface IEntity { int Id { get; set; } NameValueCollection GetSaveRuleViolations(); NameValueCollection GetDeleteRuleViolations(); } This allows the Repository class to reference these methods within its Save and Delete methods. Unit tests work fine on mock SqlClientRepository instances as well as live unit tests on the real database. However, in the MVC context: public class ClientController : Controller { private SqlClientRepository _clientRepository; public ClientController(SqlClientRepository clientRepository) { this._clientRepository = clientRepository; } public ClientController() { } // ViewResult methods ... ... } ... _clientRepository is always null. I’m using Windor Castle as an IoC container. Here is the configuration: <component id="ClientRepository" service="DomainModel.Concrete.Repository`1[[DomainModel.Entities.Client, DomainModel]], DomainModel" type="DomainModel.Concrete.SqlClientRepository, DomainModel" lifestyle="PerWebRequest"> <parameters> <connectionString>#{myConnStr}</connectionString> </parameters> </component> I’ve tried many variations in the Windsor configuration file. I suspect it’s more of a design flaw in the above code. As I'm looking over my code, it occurs to me that when registering components with an IoC container, perhaps service must always be an interface. Could this be it? Does anybody have a suggestion? Thanks in advance.

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  • java.lang.RuntimeException: Unable to start activity ComponentInfo cannot be cast to android.widget.ZoomControls

    - by Hwl
    I'm new to android development, hope you all can help me. I got this androidVNC viewer source code from internet. When i'm running the androidVNC application in the emulator, it will exit automatically then i get following errors in LogCat. Can anyone one help me? Thanks. FATAL EXCEPTION: main java.lang.RuntimeException: Unable to start activity ComponentInfo{android.androidVNC/android.androidVNC.VncCanvasActivity}: java.lang.ClassCastException: com.antlersoft.android.zoomer.ZoomControls cannot be cast to android.widget.ZoomControls at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980) at android.app.ActivityThread.access$600(ActivityThread.java:122) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4340) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.ClassCastException: com.antlersoft.android.zoomer.ZoomControls cannot be cast to android.widget.ZoomControls at android.androidVNC.VncCanvasActivity.onCreate(VncCanvasActivity.java:585) at android.app.Activity.performCreate(Activity.java:4465) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919) ... 11 more This is the ZoomControls java file: package com.antlersoft.android.zoomer; import android.content.Context; import android.util.AttributeSet; import android.view.LayoutInflater; import android.view.MotionEvent; import android.view.View; import android.view.animation.AlphaAnimation; import android.widget.ImageButton; import android.widget.LinearLayout; import android.widget.ZoomButton; public class ZoomControls extends LinearLayout { private final ZoomButton mZoomIn; private final ZoomButton mZoomOut; private final ImageButton mZoomKeyboard; public ZoomControls(Context context) { this(context, null); } public ZoomControls(Context context, AttributeSet attrs) { super(context, attrs); setFocusable(false); LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); inflater.inflate(R.layout.zoom_controls, this, // we are the parent true); mZoomIn = (ZoomButton) findViewById(R.id.zoomIn); mZoomOut = (ZoomButton) findViewById(R.id.zoomOut); mZoomKeyboard = (ImageButton) findViewById(R.id.zoomKeys); } public void setOnZoomInClickListener(OnClickListener listener) { mZoomIn.setOnClickListener(listener); } public void setOnZoomOutClickListener(OnClickListener listener) { mZoomOut.setOnClickListener(listener); } public void setOnZoomKeyboardClickListener(OnClickListener listener) { mZoomKeyboard.setOnClickListener(listener); } /* * Sets how fast you get zoom events when the user holds down the * zoom in/out buttons. */ public void setZoomSpeed(long speed) { mZoomIn.setZoomSpeed(speed); mZoomOut.setZoomSpeed(speed); } @Override public boolean onTouchEvent(MotionEvent event) { /* Consume all touch events so they don't get dispatched to the view * beneath this view. */ return true; } public void show() { fade(View.VISIBLE, 0.0f, 1.0f); } public void hide() { fade(View.GONE, 1.0f, 0.0f); } private void fade(int visibility, float startAlpha, float endAlpha) { AlphaAnimation anim = new AlphaAnimation(startAlpha, endAlpha); anim.setDuration(500); startAnimation(anim); setVisibility(visibility); } public void setIsZoomInEnabled(boolean isEnabled) { mZoomIn.setEnabled(isEnabled); } public void setIsZoomOutEnabled(boolean isEnabled) { mZoomOut.setEnabled(isEnabled); } @Override public boolean hasFocus() { return mZoomIn.hasFocus() || mZoomOut.hasFocus(); } } This is the zoom_controls XML file: <merge xmlns:android="http://schemas.android.com/apk/res/android"> <ZoomButton android:id="@+id/zoomOut" android:background="@drawable/btn_zoom_down" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <ImageButton android:id="@+id/zoomKeys" android:background="@android:drawable/ic_dialog_dialer" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <ZoomButton android:id="@+id/zoomIn" android:background="@drawable/btn_zoom_up" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </merge>

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  • using java Calendar

    - by owca
    I have a simple task. There are two classes : Ticket and Date. Ticket contains event, event place and event date which is a Date object. I also need to provide a move() method for Date object, so I used Calendar and Calendar's add(). Everything looks fine apart of the output. I constantly get 5,2,1 as the date's day,month,year. Lines with asterix return proper date. The code : Ticket class : public class Ticket { private String what; private String where; private Date when; public Ticket(String s1, String s2, Data d){ this.what = s1; this.where = s2; this.when = d; } *public Date giveDate(){ System.out.println("when in giveDate() "+this.when); return this.when; } public String toString(){ return "what: "+this.what+"\n"+"where: "+this.where+"\n"+"when: "+this.when; } } Date class: import java.util.Calendar; import java.util.GregorianCalendar; public class Date { public int day; public int month; public int year; public Date(int x, int y, int z){ *System.out.println("x: "+x); *System.out.println("y: "+y); *System.out.println("z: "+z); this.day = x; this.month = y; this.year = z; *System.out.println("this.day: "+this.day); *System.out.println("this.month: "+this.month); *System.out.println("this.year: "+this.year); } public Date move(int p){ *System.out.println("before_change: "+this.day+","+this.month+","+this.year); Calendar gc = new GregorianCalendar(this.year, this.month, this.day); System.out.println("before_adding: "+gc.DAY_OF_MONTH+","+gc.MONTH+","+gc.YEAR); gc.add(Calendar.DAY_OF_YEAR, p); System.out.println("after_adding: "+gc.DAY_OF_MONTH+","+gc.MONTH+","+gc.YEAR); this.year = gc.YEAR; this.day = gc.DAY_OF_MONTH; this.month = gc.MONTH; return this; } @Override public String toString(){ return this.day+","+this.month+","+this.year; } } Main for testing : public class Main { public static void main(String[] args) { Date date1=new Date(30,4,2002); Ticket event1=new Ticket("Peter Gabriel's gig", "London",date1 ); Ticket event2=new Ticket("Diana Kroll's concert", "Glasgow",date1 ); Date date2=event2.giveDate(); date2.move(30); Ticket event3=new Ticket("X's B-day", "some place",date2 ); System.out.println(date1); System.out.println(event1); System.out.println(event2); System.out.println(event3); } } And here's my output. I just can't get it where 5,2,1 come from :/ x: 30 y: 4 z: 2002 this.day: 30 this.month: 4 this.year: 2002 when in giveDate() 6,12,2004 before_change: 6,12,2004 before_adding: 5,2,1 after_adding: 5,2,1 5,2,1 what: Peter Gabriel's gig where: London when: 5,2,1 (...)

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  • Duplex Contract GetCallbackChannel always returns a null-instance

    - by Yaroslav
    Hi! Here is the server code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.ServiceModel; using System.Runtime.Serialization; using System.ServiceModel.Description; namespace Console_Chat { [ServiceContract(SessionMode = SessionMode.Required, CallbackContract = typeof(IMyCallbackContract))] public interface IMyService { [OperationContract(IsOneWay = true)] void NewMessageToServer(string msg); [OperationContract(IsOneWay = false)] bool ServerIsResponsible(); } [ServiceContract] public interface IMyCallbackContract { [OperationContract(IsOneWay = true)] void NewMessageToClient(string msg); [OperationContract(IsOneWay = true)] void ClientIsResponsible(); } [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)] public class MyService : IMyService { public IMyCallbackContract callback = null; /* { get { return OperationContext.Current.GetCallbackChannel<IMyCallbackContract>(); } } */ public MyService() { callback = OperationContext.Current.GetCallbackChannel<IMyCallbackContract>(); } public void NewMessageToServer(string msg) { Console.WriteLine(msg); } public void NewMessageToClient( string msg) { callback.NewMessageToClient(msg); } public bool ServerIsResponsible() { return true; } } class Server { static void Main(string[] args) { String msg = "none"; ServiceMetadataBehavior behavior = new ServiceMetadataBehavior(); ServiceHost serviceHost = new ServiceHost( typeof(MyService), new Uri("http://localhost:8080/")); serviceHost.Description.Behaviors.Add(behavior); serviceHost.AddServiceEndpoint( typeof(IMetadataExchange), MetadataExchangeBindings.CreateMexHttpBinding(), "mex"); serviceHost.AddServiceEndpoint( typeof(IMyService), new WSDualHttpBinding(), "ServiceEndpoint" ); serviceHost.Open(); Console.WriteLine("Server is up and running"); MyService server = new MyService(); server.NewMessageToClient("Hey client!"); /* do { msg = Console.ReadLine(); // callback.NewMessageToClient(msg); } while (msg != "ex"); */ Console.ReadLine(); } } } Here is the client's: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.ServiceModel; using System.Runtime.Serialization; using System.ServiceModel.Description; using Console_Chat_Client.MyHTTPServiceReference; namespace Console_Chat_Client { [ServiceContract(SessionMode = SessionMode.Required, CallbackContract = typeof(IMyCallbackContract))] public interface IMyService { [OperationContract(IsOneWay = true)] void NewMessageToServer(string msg); [OperationContract(IsOneWay = false)] bool ServerIsResponsible(); } [ServiceContract] public interface IMyCallbackContract { [OperationContract(IsOneWay = true)] void NewMessageToClient(string msg); [OperationContract(IsOneWay = true)] void ClientIsResponsible(); } public class MyCallback : Console_Chat_Client.MyHTTPServiceReference.IMyServiceCallback { static InstanceContext ctx = new InstanceContext(new MyCallback()); static MyServiceClient client = new MyServiceClient(ctx); public void NewMessageToClient(string msg) { Console.WriteLine(msg); } public void ClientIsResponsible() { } class Client { static void Main(string[] args) { String msg = "none"; client.NewMessageToServer(String.Format("Hello server!")); do { msg = Console.ReadLine(); if (msg != "ex") client.NewMessageToServer(msg); else client.NewMessageToServer(String.Format("Client terminated")); } while (msg != "ex"); } } } } callback = OperationContext.Current.GetCallbackChannel(); This line constanly throws a NullReferenceException, what's the problem? Thanks!

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  • Can anyone help convert this VB Webservice?

    - by CraigJSte
    I can't figure it out for the life of me.. I'm using SQL DataSet Query to iterate to a Class Object which acts as a Data Model for Flex... Initially I used VB.net but now need to convert to C#.. This conversion is done except for the last section where I create a DataRow arow and then try to add the DataSet Values to the Class (Results Class)... I get an error message.. 'VTResults.Results.Ticker' is inaccessible due to its protection level (this is down at the bottom) using System; using System.Web; using System.Collections; using System.Web.Services; using System.Web.Services.Protocols; using System.Data; using System.Data.SqlClient; using System.Configuration; /// <summary> /// Summary description for VTResults /// </summary> [WebService(Namespace = "http://velocitytrading.net/ResultsVT.aspx")] [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] public class VTResults : System.Web.Services.WebService { public class Results { string Ticker; string BuyDate; decimal Buy; string SellDate; decimal Sell; string Profit; decimal Period; } [WebMethod] public Results[] GetResults() { string conn = ConfigurationManager.ConnectionStrings["LocalSqlServer"].ConnectionString; SqlConnection myconn = new SqlConnection(conn); SqlCommand mycomm = new SqlCommand(); SqlDataAdapter myda = new SqlDataAdapter(); DataSet myds = new DataSet(); mycomm.CommandType = CommandType.StoredProcedure; mycomm.Connection = myconn; mycomm.CommandText = "dbo.Results"; myconn.Open(); myda.SelectCommand = mycomm; myda.Fill(myds); myconn.Close(); myconn.Dispose(); int i = 0; Results[] dts = new Results[myds.Tables[0].Rows.Count]; foreach(DataRow arow in myds.Tables[0].Rows) { dts[i] = new Results(); dts[i].Ticker = arow["Ticker"]; dts[i].BuyDate = arow["BuyDate"]; dts[1].Buy = arow["Buy"]; dts[i].SellDate = arow["SellDate"]; dts[i].Sell = arow["Sell"]; dts[i].Profit = arow["Profit"]; dts[i].Period = arow["Period"]; i+=1; } return dts; } } The VB.NET WEBSERVICE that runs fine which I am trying to convert to C# is here. Imports System.Web Imports System.Web.Services Imports System.Web.Services.Protocols Imports System.Data Imports System.Data.SqlClient <WebService(Namespace:="http://localhost:2597/Results/ResultsVT.aspx")> _ <WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _ <Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _ Public Class VTResults Inherits System.Web.Services.WebService Public Class Results Public Ticker As String Public BuyDate As String Public Buy As Decimal Public SellDate As String Public Sell As Decimal Public Profit As String Public Period As Decimal End Class <WebMethod()> _ Public Function GetResults() As Results() Try Dim conn As String = ConfigurationManager.ConnectionStrings("LocalSqlServer").ConnectionString Dim myconn = New SqlConnection(conn) Dim mycomm As New SqlCommand Dim myda As New SqlDataAdapter Dim myds As New DataSet mycomm.CommandType = CommandType.StoredProcedure mycomm.Connection = myconn mycomm.CommandText = "dbo.Results" myconn.Open() myda.SelectCommand = mycomm myda.Fill(myds) myconn.Close() myconn.Dispose() Dim i As Integer i = 0 Dim dts As Results() = New Results(myds.Tables(0).Rows.Count - 1) {} Dim aRow As DataRow For Each aRow In myds.Tables(0).Rows dts(i) = New Results dts(i).Ticker = aRow("Ticker") dts(i).BuyDate = aRow("BuyDate") dts(i).Buy = aRow("Buy") dts(i).SellDate = aRow("SellDate") dts(i).Sell = aRow("Sell") dts(i).Profit = aRow("Profit") dts(i).Period = aRow("Period") i += 1 Next Return dts Catch ex As DataException Throw ex End Try End Function End Class

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  • Saving child collections with NHibernate

    - by Ben
    Hi, I am in the process or learning NHibernate so bare with me. I have an Order class and a Transaction class. Order has a one to many association with transaction. The transaction table in my database has a not null constraint on the OrderId foreign key. Order class: public class Order { public virtual Guid Id { get; set; } public virtual DateTime CreatedOn { get; set; } public virtual decimal Total { get; set; } public virtual ICollection<Transaction> Transactions { get; set; } public Order() { Transactions = new HashSet<Transaction>(); } } Order Mapping: <class name="Order" table="Orders"> <cache usage="read-write"/> <id name="Id"> <generator class="guid"/> </id> <property name="CreatedOn" type="datetime"/> <property name="Total" type="decimal"/> <set name="Transactions" table="Transactions" lazy="false" inverse="true"> <key column="OrderId"/> <one-to-many class="Transaction"/> </set> Transaction Class: public class Transaction { public virtual Guid Id { get; set; } public virtual DateTime ExecutedOn { get; set; } public virtual bool Success { get; set; } public virtual Order Order { get; set; } } Transaction Mapping: <class name="Transaction" table="Transactions"> <cache usage="read-write"/> <id name="Id" column="Id" type="Guid"> <generator class="guid"/> </id> <property name="ExecutedOn" type="datetime"/> <property name="Success" type="bool"/> <many-to-one name="Order" class="Order" column="OrderId" not-null="true"/> Really I don't want a bidirectional association. There is no need for my transaction objects to reference their order object directly (I just need to access the transactions of an order). However, I had to add this so that Order.Transactions is persisted to the database: Repository: public void Update(Order entity) { using (ISession session = NHibernateHelper.OpenSession()) { using (ITransaction transaction = session.BeginTransaction()) { session.Update(entity); foreach (var tx in entity.Transactions) { tx.Order = entity; session.SaveOrUpdate(tx); } transaction.Commit(); } } } My problem is that this will then issue an update for every transaction on the order collection (regardless of whether it has changed or not). What I was trying to get around was having to explicitly save the transaction before saving the order and instead just add the transactions to the order and then save the order: public void Can_add_transaction_to_existing_order() { var orderRepo = new OrderRepository(); var order = orderRepo.GetById(new Guid("aa3b5d04-c5c8-4ad9-9b3e-9ce73e488a9f")); Transaction tx = new Transaction(); tx.ExecutedOn = DateTime.Now; tx.Success = true; order.Transactions.Add(tx); orderRepo.Update(order); } Although I have found quite a few articles covering the set up of a one-to-many association, most of these discuss retrieving of data and not persisting back. Many thanks, Ben

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  • Prevent lazy loading in nHibernate

    - by Ciaran
    Hi, I'm storing some blobs in my database, so I have a Document table and a DocumentContent table. Document contains a filename, description etc and has a DocumentContent property. I have a Silverlight client, so I don't want to load up and send the DocumentContent to the client unless I explicity ask for it, but I'm having trouble doing this. I've read the blog post by Davy Brion. I have tried placing lazy=false in my config and removing the virtual access modifier but have had no luck with it as yet. Every time I do a Session.Get(id), the DocumentContent is retrieved via an outer join. I only want this property to be populated when I explicity join onto this table and ask for it. Any help is appreciated. My NHibernate mapping is as follows: <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Jrm.Model" namespace="Jrm.Model"> <class name="JrmDocument" lazy="false"> <id name="JrmDocumentID"> <generator class="native" /> </id> <property name="FileName"/> <property name="Description"/> <many-to-one name="DocumentContent" class="JrmDocumentContent" unique="true" column="JrmDocumentContentID" lazy="false"/> </class> <class name="JrmDocumentContent" lazy="false"> <id name="JrmDocumentContentID"> <generator class="native" /> </id> <property name="Content" type="BinaryBlob" lazy="false"> <column name="FileBytes" sql-type="varbinary(max)"/> </property> </class> </hibernate-mapping> and my classes are: [DataContract] public class JrmDocument : ModelBase { private int jrmDocumentID; private JrmDocumentContent documentContent; private long maxFileSize; private string fileName; private string description; public JrmDocument() { } public JrmDocument(string fileName, long maxFileSize) { DocumentContent = new JrmDocumentContent(File.ReadAllBytes(fileName)); FileName = new FileInfo(fileName).Name; } [DataMember] public virtual int JrmDocumentID { get { return jrmDocumentID; } set { jrmDocumentID = value; OnPropertyChanged("JrmDocumentID"); } } [DataMember] public JrmDocumentContent DocumentContent { get { return documentContent; } set { documentContent = value; OnPropertyChanged("DocumentContent"); } } [DataMember] public virtual long MaxFileSize { get { return maxFileSize; } set { maxFileSize = value; OnPropertyChanged("MaxFileSize"); } } [DataMember] public virtual string FileName { get { return fileName; } set { fileName = value; OnPropertyChanged("FileName"); } } [DataMember] public virtual string Description { get { return description; } set { description = value; OnPropertyChanged("Description"); } } } [DataContract] public class JrmDocumentContent : ModelBase { private int jrmDocumentContentID; private byte[] content; public JrmDocumentContent() { } public JrmDocumentContent(byte[] bytes) { Content = bytes; } [DataMember] public int JrmDocumentContentID { get { return jrmDocumentContentID; } set { jrmDocumentContentID = value; OnPropertyChanged("JrmDocumentContentID"); } } [DataMember] public byte[] Content { get { return content; } set { content = value; OnPropertyChanged("Content"); } } }

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  • How to remove a model object from an EMF model and its GEF Editor via Adapter

    - by s.d
    This question is principally a follow-up to my question about EMF listening mechanisms. So, I have a third-party EMF model (uneditable) which is based on a generic graph model. The structure is as follows: Project | ItemGraph | Item | Document | DocumentGraph / | \ Tokens Nodes Relations(Edges) I have a GEF editor which works on the DocumentGraph (i.e., not the root object, perhaps this is a problem?): getGraphicalViewer().setContents(documentGraph). THe editor has the following edit part structure: DocumentGraphEP / \ Primary Connection LayerEP LayerEP / \ | TokenEP NodeEP RelationEP PrimaryLayerEP and ConnectionLayerEP both have simple Strings as model, which are not represented in the EMF (domain) model. They are simply used to add a primary (i.e., node) layer, and a connection layer (with ShortestPathConnectionRouter) to the editor. Problem: I am trying to get myself into the workings of EMF adapters, and have tried to make use of the available tutorials, mainly the EMF-GEF Eclipse tutorial, vainolo's blog, and vogella's tutorial. I thought I'd start with an easy thing, so tried to remove a node from the graph and see if I get it to work. Which I didn't, and I don't see where the problem is. I can select a node, and have the generic delete Action in my toolbar, but when I click it, nothing happens. Here is the respective source code for the different responsible parts. Please be so kind to point me to any errors (of thinking, coding errors, whathaveyou) you can find. NodeEditPart public class NodeEditPart extends AbstractGraphicalEditPart implements Adapter { protected IFigure createFigure() { return new NodeFigure(); } protected void createEditPolicies() { .... installEditPolicy(EditPolicy.COMPONENT_ROLE, new NodeComponentEditPolicy()); } protected void refreshVisuals() { NodeFigure figure = (NodeFigure) getFigure(); SNode model = (SNode) getModel(); PrimaryLayerEditPart parent = (PrimaryLayerEditPart) getParent(); // Set text figure.getLabel().setText(model.getSName()); .... } public void activate() { if (isActive()) return; // start listening for changes in the model ((Notifier)getModel()).eAdapters().add(this); super.activate(); } public void deactivate() { if (!isActive()) return; // stop listening for changes in the model ((Notifier)getModel()).eAdapters().remove(this); super.deactivate(); } private Notifier getSDocumentGraph() { return ((SNode)getModel()).getSDocumentGraph(); } @Override public void notifyChanged(Notification notification) { int type = notification.getEventType(); switch( type ) { case Notification.ADD: case Notification.ADD_MANY: case Notification.REMOVE: case Notification.REMOVE_MANY: refreshChildren(); break; case Notification.SET: refreshVisuals(); break; } } @Override public Notifier getTarget() { return target; } @Override public void setTarget(Notifier newTarget) { this.target = newTarget; } @Override public boolean isAdapterForType(Object type) { return type.equals(getModel().getClass()); } } NodeComponentEditPolicy public class NodeComponentEditPolicy extends ComponentEditPolicy { public NodeComponentEditPolicy() { super(); } protected Command createDeleteCommand(GroupRequest deleteRequest) { DeleteNodeCommand cmd = new DeleteNodeCommand(); cmd.setSNode((SNode) getHost().getModel()); return cmd; } } DeleteNodeCommand public class DeleteNodeCommand extends Command { private SNode node; private SDocumentGraph graph; @Override public void execute() { node.setSDocumentGraph(null); } @Override public void undo() { node.setSDocumentGraph(graph); } public void setSNode(SNode node) { this.node = node; this.graph = node.getSDocumentGraph(); } } All seems to work fine: When a node is selected in the editor, the delete symbol is activated in the toolbar, but when it is clicked, nothing happens in the editor. I'd be very thankful for any pointers :).

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  • How do I use constructor dependency injection to supply Models from a collection to their ViewModels

    - by GraemeF
    I'm using constructor dependency injection in my WPF application and I keep running into the following pattern, so would like to get other people's opinion on it and hear about alternative solutions. The goal is to wire up a hierarchy of ViewModels to a similar hierarchy of Models, so that the responsibility for presenting the information in each model lies with its own ViewModel implementation. (The pattern also crops up under other circumstances but MVVM should make for a good example.) Here's a simplified example. Given that I have a model that has a collection of further models: public interface IPerson { IEnumerable<IAddress> Addresses { get; } } public interface IAddress { } I would like to mirror this hierarchy in the ViewModels so that I can bind a ListBox (or whatever) to a collection in the Person ViewModel: public interface IPersonViewModel { ObservableCollection<IAddressViewModel> Addresses { get; } void Initialize(); } public interface IAddressViewModel { } The child ViewModel needs to present the information from the child Model, so it's injected via the constructor: public class AddressViewModel : IAddressViewModel { private readonly IAddress _address; public AddressViewModel(IAddress address) { _address = address; } } The question is, what is the best way to supply the child Model to the corresponding child ViewModel? The example is trivial, but in a typical real case the ViewModels have more dependencies - each of which has its own dependencies (and so on). I'm using Unity 1.2 (although I think the question is relevant across the other IoC containers), and I am using Caliburn's view strategies to automatically find and wire up the appropriate View to a ViewModel. Here is my current solution: The parent ViewModel needs to create a child ViewModel for each child Model, so it has a factory method added to its constructor which it uses during initialization: public class PersonViewModel : IPersonViewModel { private readonly Func<IAddress, IAddressViewModel> _addressViewModelFactory; private readonly IPerson _person; public PersonViewModel(IPerson person, Func<IAddress, IAddressViewModel> addressViewModelFactory) { _addressViewModelFactory = addressViewModelFactory; _person = person; Addresses = new ObservableCollection<IAddressViewModel>(); } public ObservableCollection<IAddressViewModel> Addresses { get; private set; } public void Initialize() { foreach (IAddress address in _person.Addresses) Addresses.Add(_addressViewModelFactory(address)); } } A factory method that satisfies the Func<IAddress, IAddressViewModel> interface is registered with the main UnityContainer. The factory method uses a child container to register the IAddress dependency that is required by the ViewModel and then resolves the child ViewModel: public class Factory { private readonly IUnityContainer _container; public Factory(IUnityContainer container) { _container = container; } public void RegisterStuff() { _container.RegisterInstance<Func<IAddress, IAddressViewModel>>(CreateAddressViewModel); } private IAddressViewModel CreateAddressViewModel(IAddress model) { IUnityContainer childContainer = _container.CreateChildContainer(); childContainer.RegisterInstance(model); return childContainer.Resolve<IAddressViewModel>(); } } Now, when the PersonViewModel is initialized, it loops through each Address in the Model and calls CreateAddressViewModel() (which was injected via the Func<IAddress, IAddressViewModel> argument). CreateAddressViewModel() creates a temporary child container and registers the IAddress model so that when it resolves the IAddressViewModel from the child container the AddressViewModel gets the correct instance injected via its constructor. This seems to be a good solution to me as the dependencies of the ViewModels are very clear and they are easily testable and unaware of the IoC container. On the other hand, performance is OK but not great as a lot of temporary child containers can be created. Also I end up with a lot of very similar factory methods. Is this the best way to inject the child Models into the child ViewModels with Unity? Is there a better (or faster) way to do it in other IoC containers, e.g. Autofac? How would this problem be tackled with MEF, given that it is not a traditional IoC container but is still used to compose objects?

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  • Two-way databinding of a custom templated control. Eval works, but not Bind.

    - by Jason
    I hate long code snippets and I'm sorry about this one, but it turns out that this asp.net stuff can't get much shorter and it's so specific that I haven't been able to generalize it without a full code listing. I just want simple two-way, declarative databinding to a single instance of an object. Not a list of objects of a type with a bunch of NotImplementedExceptions for Add, Delete, and Select, but just a single view-state persisted object. This is certainly something that can be done but I've struggled with an implementation for years. This newest, closest implementation was inspired by this article from 4-Guys-From-Rolla, http://msdn.microsoft.com/en-us/library/aa478964.aspx. Unfortunately, after implementing, I'm getting the following error and I don't know what I'm missing: System.InvalidOperationException: Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control. If I don't use Bind(), and only use Eval() functionality, it works. In that way, the error is especially confusing. Here's the simplified codeset that still produces the error: using System.ComponentModel; namespace System.Web.UI.WebControls.Special { public class SampleFormData { public string SampleString = "Sample String Data"; public int SampleInt = -1; } [ToolboxItem(false)] public class SampleSpecificFormDataContainer : WebControl, INamingContainer { SampleSpecificEntryForm entryForm; internal SampleSpecificEntryForm EntryForm { get { return entryForm; } } [Bindable(true), Category("Data")] public string SampleString { get { return entryForm.FormData.SampleString; } set { entryForm.FormData.SampleString = value; } } [Bindable(true), Category("Data")] public int SampleInt { get { return entryForm.FormData.SampleInt; } set { entryForm.FormData.SampleInt = value; } } internal SampleSpecificFormDataContainer(SampleSpecificEntryForm entryForm) { this.entryForm = entryForm; } } public class SampleSpecificEntryForm : WebControl, INamingContainer { #region Template private IBindableTemplate formTemplate = null; [Browsable(false), DefaultValue(null), TemplateContainer(typeof(SampleSpecificFormDataContainer), ComponentModel.BindingDirection.TwoWay), PersistenceMode(PersistenceMode.InnerProperty)] public virtual IBindableTemplate FormTemplate { get { return formTemplate; } set { formTemplate = value; } } #endregion #region Viewstate SampleFormData FormDataVS { get { return (ViewState["FormData"] as SampleFormData) ?? new SampleFormData(); } set { ViewState["FormData"] = value; SaveViewState(); } } #endregion public override ControlCollection Controls { get { EnsureChildControls(); return base.Controls; } } private SampleSpecificFormDataContainer formDataContainer = null; [Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)] public SampleSpecificFormDataContainer FormDataContainer { get { EnsureChildControls(); return formDataContainer; } } [Bindable(true), Browsable(false)] public SampleFormData FormData { get { return FormDataVS; } set { FormDataVS = value; } } protected override void CreateChildControls() { if (!this.ChildControlsCreated) { Controls.Clear(); formDataContainer = new SampleSpecificFormDataContainer(this); Controls.Add(formDataContainer); FormTemplate.InstantiateIn(formDataContainer); this.ChildControlsCreated = true; } } public override void DataBind() { CreateChildControls(); base.DataBind(); } } } With an ASP.NET page the following: <%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeBehind="Default2.aspx.cs" Inherits="EntryFormTest._Default2" EnableEventValidation="false" %> <%@ Register Assembly="EntryForm" Namespace="System.Web.UI.WebControls.Special" TagPrefix="cc1" %> <asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent"> </asp:Content> <asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent"> <h2> Welcome to ASP.NET! </h2> <cc1:SampleSpecificEntryForm ID="EntryForm1" runat="server"> <FormTemplate> <asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("SampleString") %>'></asp:TextBox><br /> <h3>(<%# Container.SampleString %>)</h3><br /> <asp:Button ID="Button1" runat="server" Text="Button" /> </FormTemplate> </cc1:SampleSpecificEntryForm> </asp:Content> Default2.aspx.cs using System; namespace EntryFormTest { public partial class _Default2 : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { EntryForm1.DataBind(); } } } Thanks for any help!

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  • C# Can anyone help convert this VB Webservice?

    - by CraigJSte
    I can't figure it out for the life of me.. I'm using SQL DataSet Query to iterate to a Class Object which acts as a Data Model for Flex... Initially I used VB.net but now need to convert to C#.. This conversion is done except for the last section where I create a DataRow arow and then try to add the DataSet Values to the Class (Results Class)... I get an error message.. 'VTResults.Results.Ticker' is inaccessible due to its protection level (this is down at the bottom) using System; using System.Web; using System.Collections; using System.Web.Services; using System.Web.Services.Protocols; using System.Data; using System.Data.SqlClient; using System.Configuration; /// <summary> /// Summary description for VTResults /// </summary> [WebService(Namespace = "http://velocitytrading.net/ResultsVT.aspx")] [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] public class VTResults : System.Web.Services.WebService { public class Results { string Ticker; string BuyDate; decimal Buy; string SellDate; decimal Sell; string Profit; decimal Period; } [WebMethod] public Results[] GetResults() { string conn = ConfigurationManager.ConnectionStrings["LocalSqlServer"].ConnectionString; SqlConnection myconn = new SqlConnection(conn); SqlCommand mycomm = new SqlCommand(); SqlDataAdapter myda = new SqlDataAdapter(); DataSet myds = new DataSet(); mycomm.CommandType = CommandType.StoredProcedure; mycomm.Connection = myconn; mycomm.CommandText = "dbo.Results"; myconn.Open(); myda.SelectCommand = mycomm; myda.Fill(myds); myconn.Close(); myconn.Dispose(); int i = 0; Results[] dts = new Results[myds.Tables[0].Rows.Count]; foreach(DataRow arow in myds.Tables[0].Rows) { dts[i] = new Results(); dts[i].Ticker = arow["Ticker"]; dts[i].BuyDate = arow["BuyDate"]; dts[1].Buy = arow["Buy"]; dts[i].SellDate = arow["SellDate"]; dts[i].Sell = arow["Sell"]; dts[i].Profit = arow["Profit"]; dts[i].Period = arow["Period"]; i+=1; } return dts; } } The VB.NET WEBSERVICE that runs fine which I am trying to convert to C# is here. Imports System.Web Imports System.Web.Services Imports System.Web.Services.Protocols Imports System.Data Imports System.Data.SqlClient <WebService(Namespace:="http://localhost:2597/Results/ResultsVT.aspx")> _ <WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _ <Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _ Public Class VTResults Inherits System.Web.Services.WebService Public Class Results Public Ticker As String Public BuyDate As String Public Buy As Decimal Public SellDate As String Public Sell As Decimal Public Profit As String Public Period As Decimal End Class <WebMethod()> _ Public Function GetResults() As Results() Try Dim conn As String = ConfigurationManager.ConnectionStrings("LocalSqlServer").ConnectionString Dim myconn = New SqlConnection(conn) Dim mycomm As New SqlCommand Dim myda As New SqlDataAdapter Dim myds As New DataSet mycomm.CommandType = CommandType.StoredProcedure mycomm.Connection = myconn mycomm.CommandText = "dbo.Results" myconn.Open() myda.SelectCommand = mycomm myda.Fill(myds) myconn.Close() myconn.Dispose() Dim i As Integer i = 0 Dim dts As Results() = New Results(myds.Tables(0).Rows.Count - 1) {} Dim aRow As DataRow For Each aRow In myds.Tables(0).Rows dts(i) = New Results dts(i).Ticker = aRow("Ticker") dts(i).BuyDate = aRow("BuyDate") dts(i).Buy = aRow("Buy") dts(i).SellDate = aRow("SellDate") dts(i).Sell = aRow("Sell") dts(i).Profit = aRow("Profit") dts(i).Period = aRow("Period") i += 1 Next Return dts Catch ex As DataException Throw ex End Try End Function End Class

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