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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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• Database Tutorial: The method open() is undefined for the type MainActivity.DBAdapter

  - by user2203633

  I am trying to do this database tutorial on SQLite Eclipse: https://www.youtube.com/watch?v=j-IV87qQ00M But I get a few errors at the end.. at db.ppen(); i get error: The method open() is undefined for the type MainActivity.DBAdapter and similar for insert record and close. MainActivity: package com.example.studentdatabase; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import android.app.Activity; import android.app.ListActivity; import android.content.Intent; import android.database.Cursor; import android.os.Bundle; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.Button; import android.widget.Toast; public class MainActivity extends Activity { /** Called when the activity is first created. */ //DBAdapter db = new DBAdapter(this); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button addBtn = (Button)findViewById(R.id.add); addBtn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Intent i = new Intent(MainActivity.this, addassignment.class); startActivity(i); } }); try { String destPath = "/data/data/" + getPackageName() + "/databases/AssignmentDB"; File f = new File(destPath); if (!f.exists()) { CopyDB( getBaseContext().getAssets().open("mydb"), new FileOutputStream(destPath)); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } DBAdapter db = new DBAdapter(); //---add an assignment--- db.open(); long id = db.insertRecord("Hello World", "2/18/2012", "DPR 224", "First Android Project"); id = db.insertRecord("Workbook Exercises", "3/1/2012", "MAT 100", "Do odd numbers"); db.close(); //---get all Records--- /* db.open(); Cursor c = db.getAllRecords(); if (c.moveToFirst()) { do { DisplayRecord(c); } while (c.moveToNext()); } db.close(); */ /* //---get a Record--- db.open(); Cursor c = db.getRecord(2); if (c.moveToFirst()) DisplayRecord(c); else Toast.makeText(this, "No Assignments found", Toast.LENGTH_LONG).show(); db.close(); */ //---update Record--- /* db.open(); if (db.updateRecord(1, "Hello Android", "2/19/2012", "DPR 224", "First Android Project")) Toast.makeText(this, "Update successful.", Toast.LENGTH_LONG).show(); else Toast.makeText(this, "Update failed.", Toast.LENGTH_LONG).show(); db.close(); */ /* //---delete a Record--- db.open(); if (db.deleteRecord(1)) Toast.makeText(this, "Delete successful.", Toast.LENGTH_LONG).show(); else Toast.makeText(this, "Delete failed.", Toast.LENGTH_LONG).show(); db.close(); */ } private class DBAdapter extends BaseAdapter { private LayoutInflater mInflater; //private ArrayList<> @Override public int getCount() { return 0; } @Override public Object getItem(int arg0) { return null; } @Override public long getItemId(int arg0) { return 0; } @Override public View getView(int arg0, View arg1, ViewGroup arg2) { return null; } } public void CopyDB(InputStream inputStream, OutputStream outputStream) throws IOException { //---copy 1K bytes at a time--- byte[] buffer = new byte[1024]; int length; while ((length = inputStream.read(buffer)) > 0) { outputStream.write(buffer, 0, length); } inputStream.close(); outputStream.close(); } public void DisplayRecord(Cursor c) { Toast.makeText(this, "id: " + c.getString(0) + "\n" + "Title: " + c.getString(1) + "\n" + "Due Date: " + c.getString(2), Toast.LENGTH_SHORT).show(); } public void addAssignment(View view) { Intent i = new Intent("com.pinchtapzoom.addassignment"); startActivity(i); Log.d("TAG", "Clicked"); } } DBAdapter code: package com.example.studentdatabase; public class DBAdapter { public static final String KEY_ROWID = "id"; public static final String KEY_TITLE = "title"; public static final String KEY_DUEDATE = "duedate"; public static final String KEY_COURSE = "course"; public static final String KEY_NOTES = "notes"; private static final String TAG = "DBAdapter"; private static final String DATABASE_NAME = "AssignmentsDB"; private static final String DATABASE_TABLE = "assignments"; private static final int DATABASE_VERSION = 2; private static final String DATABASE_CREATE = "create table if not exists assignments (id integer primary key autoincrement, " + "title VARCHAR not null, duedate date, course VARCHAR, notes VARCHAR );"; private final 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) { try { db.execSQL(DATABASE_CREATE); } catch (SQLException e) { e.printStackTrace(); } } @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 contacts"); 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 record into the database--- public long insertRecord(String title, String duedate, String course, String notes) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_TITLE, title); initialValues.put(KEY_DUEDATE, duedate); initialValues.put(KEY_COURSE, course); initialValues.put(KEY_NOTES, notes); return db.insert(DATABASE_TABLE, null, initialValues); } //---deletes a particular record--- public boolean deleteContact(long rowId) { return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0; } //---retrieves all the records--- public Cursor getAllRecords() { return db.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE, KEY_DUEDATE, KEY_COURSE, KEY_NOTES}, null, null, null, null, null); } //---retrieves a particular record--- public Cursor getRecord(long rowId) throws SQLException { Cursor mCursor = db.query(true, DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE, KEY_DUEDATE, KEY_COURSE, KEY_NOTES}, KEY_ROWID + "=" + rowId, null, null, null, null, null); if (mCursor != null) { mCursor.moveToFirst(); } return mCursor; } //---updates a record--- public boolean updateRecord(long rowId, String title, String duedate, String course, String notes) { ContentValues args = new ContentValues(); args.put(KEY_TITLE, title); args.put(KEY_DUEDATE, duedate); args.put(KEY_COURSE, course); args.put(KEY_NOTES, notes); return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0; } } addassignment code: package com.example.studentdatabase; public class addassignment extends Activity { DBAdapter db = new DBAdapter(this); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.add); } public void addAssignment(View v) { Log.d("test", "adding"); //get data from form EditText nameTxt = (EditText)findViewById(R.id.editTitle); EditText dateTxt = (EditText)findViewById(R.id.editDuedate); EditText courseTxt = (EditText)findViewById(R.id.editCourse); EditText notesTxt = (EditText)findViewById(R.id.editNotes); db.open(); long id = db.insertRecord(nameTxt.getText().toString(), dateTxt.getText().toString(), courseTxt.getText().toString(), notesTxt.getText().toString()); db.close(); nameTxt.setText(""); dateTxt.setText(""); courseTxt.setText(""); notesTxt.setText(""); Toast.makeText(addassignment.this,"Assignment Added", Toast.LENGTH_LONG).show(); } public void viewAssignments(View v) { Intent i = new Intent(this, MainActivity.class); startActivity(i); } } What is wrong here? Thanks in advance.

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• Bulk inserting best way to about it? + Helping me understand fully what I found so far

  - by chobo2

  Hi So I saw this post here and read it and it seems like bulk copy might be the way to go. http://stackoverflow.com/questions/682015/whats-the-best-way-to-bulk-database-inserts-from-c I still have some questions and want to know how things actually work. So I found 2 tutorials. http://www.codeproject.com/KB/cs/MultipleInsertsIn1dbTrip.aspx#_Toc196622241 http://www.codeproject.com/KB/linq/BulkOperations_LinqToSQL.aspx First way uses 2 ado.net 2.0 features. BulkInsert and BulkCopy. the second one uses linq to sql and OpenXML. This sort of appeals to me as I am using linq to sql already and prefer it over ado.net. However as one person pointed out in the posts what he just going around the issue at the cost of performance( nothing wrong with that in my opinion) First I will talk about the 2 ways in the first tutorial I am using VS2010 Express, .net 4.0, MVC 2.0, SQl Server 2005 Is ado.net 2.0 the most current version? Based on the technology I am using, is there some updates to what I am going to show that would improve it somehow? Is there any thing that these tutorial left out that I should know about? BulkInsert I am using this table for all the examples. CREATE TABLE [dbo].[TBL_TEST_TEST] ( ID INT IDENTITY(1,1) PRIMARY KEY, [NAME] [varchar](50) ) SP Code USE [Test] GO /****** Object: StoredProcedure [dbo].[sp_BatchInsert] Script Date: 05/19/2010 15:12:47 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO ALTER PROCEDURE [dbo].[sp_BatchInsert] (@Name VARCHAR(50) ) AS BEGIN INSERT INTO TBL_TEST_TEST VALUES (@Name); END C# Code /// <summary> /// Another ado.net 2.0 way that uses a stored procedure to do a bulk insert. /// Seems slower then "BatchBulkCopy" way and it crashes when you try to insert 500,000 records in one go. /// http://www.codeproject.com/KB/cs/MultipleInsertsIn1dbTrip.aspx#_Toc196622241 /// </summary> private static void BatchInsert() { // Get the DataTable with Rows State as RowState.Added DataTable dtInsertRows = GetDataTable(); SqlConnection connection = new SqlConnection(connectionString); SqlCommand command = new SqlCommand("sp_BatchInsert", connection); command.CommandType = CommandType.StoredProcedure; command.UpdatedRowSource = UpdateRowSource.None; // Set the Parameter with appropriate Source Column Name command.Parameters.Add("@Name", SqlDbType.VarChar, 50, dtInsertRows.Columns[0].ColumnName); SqlDataAdapter adpt = new SqlDataAdapter(); adpt.InsertCommand = command; // Specify the number of records to be Inserted/Updated in one go. Default is 1. adpt.UpdateBatchSize = 1000; connection.Open(); int recordsInserted = adpt.Update(dtInsertRows); connection.Close(); } So first thing is the batch size. Why would you set a batch size to anything but the number of records you are sending? Like I am sending 500,000 records so I did a Batch size of 500,000. Next why does it crash when I do this? If I set it to 1000 for batch size it works just fine. System.Data.SqlClient.SqlException was unhandled Message="A transport-level error has occurred when sending the request to the server. (provider: Shared Memory Provider, error: 0 - No process is on the other end of the pipe.)" Source=".Net SqlClient Data Provider" ErrorCode=-2146232060 Class=20 LineNumber=0 Number=233 Server="" State=0 StackTrace: at System.Data.Common.DbDataAdapter.UpdatedRowStatusErrors(RowUpdatedEventArgs rowUpdatedEvent, BatchCommandInfo[] batchCommands, Int32 commandCount) at System.Data.Common.DbDataAdapter.UpdatedRowStatus(RowUpdatedEventArgs rowUpdatedEvent, BatchCommandInfo[] batchCommands, Int32 commandCount) at System.Data.Common.DbDataAdapter.Update(DataRow[] dataRows, DataTableMapping tableMapping) at System.Data.Common.DbDataAdapter.UpdateFromDataTable(DataTable dataTable, DataTableMapping tableMapping) at System.Data.Common.DbDataAdapter.Update(DataTable dataTable) at TestIQueryable.Program.BatchInsert() in C:\Users\a\Downloads\TestIQueryable\TestIQueryable\TestIQueryable\Program.cs:line 124 at TestIQueryable.Program.Main(String[] args) in C:\Users\a\Downloads\TestIQueryable\TestIQueryable\TestIQueryable\Program.cs:line 16 InnerException: Time it took to insert 500,000 records with insert batch size of 1000 took "2 mins and 54 seconds" Of course this is no official time I sat there with a stop watch( I am sure there are better ways but was too lazy to look what they where) So I find that kinda slow compared to all my other ones(expect the linq to sql insert one) and I am not really sure why. Next I looked at bulkcopy /// <summary> /// An ado.net 2.0 way to mass insert records. This seems to be the fastest. /// http://www.codeproject.com/KB/cs/MultipleInsertsIn1dbTrip.aspx#_Toc196622241 /// </summary> private static void BatchBulkCopy() { // Get the DataTable DataTable dtInsertRows = GetDataTable(); using (SqlBulkCopy sbc = new SqlBulkCopy(connectionString, SqlBulkCopyOptions.KeepIdentity)) { sbc.DestinationTableName = "TBL_TEST_TEST"; // Number of records to be processed in one go sbc.BatchSize = 500000; // Map the Source Column from DataTabel to the Destination Columns in SQL Server 2005 Person Table // sbc.ColumnMappings.Add("ID", "ID"); sbc.ColumnMappings.Add("NAME", "NAME"); // Number of records after which client has to be notified about its status sbc.NotifyAfter = dtInsertRows.Rows.Count; // Event that gets fired when NotifyAfter number of records are processed. sbc.SqlRowsCopied += new SqlRowsCopiedEventHandler(sbc_SqlRowsCopied); // Finally write to server sbc.WriteToServer(dtInsertRows); sbc.Close(); } } This one seemed to go really fast and did not even need a SP( can you use SP with bulk copy? If you can would it be better?) BatchCopy had no problem with a 500,000 batch size.So again why make it smaller then the number of records you want to send? I found that with BatchCopy and 500,000 batch size it took only 5 seconds to complete. I then tried with a batch size of 1,000 and it only took 8 seconds. So much faster then the bulkinsert one above. Now I tried the other tutorial. USE [Test] GO /****** Object: StoredProcedure [dbo].[spTEST_InsertXMLTEST_TEST] Script Date: 05/19/2010 15:39:03 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO ALTER PROCEDURE [dbo].[spTEST_InsertXMLTEST_TEST](@UpdatedProdData nText) AS DECLARE @hDoc int exec sp_xml_preparedocument @hDoc OUTPUT,@UpdatedProdData INSERT INTO TBL_TEST_TEST(NAME) SELECT XMLProdTable.NAME FROM OPENXML(@hDoc, 'ArrayOfTBL_TEST_TEST/TBL_TEST_TEST', 2) WITH ( ID Int, NAME varchar(100) ) XMLProdTable EXEC sp_xml_removedocument @hDoc C# code. /// <summary> /// This is using linq to sql to make the table objects. /// It is then serailzed to to an xml document and sent to a stored proedure /// that then does a bulk insert(I think with OpenXML) /// http://www.codeproject.com/KB/linq/BulkOperations_LinqToSQL.aspx /// </summary> private static void LinqInsertXMLBatch() { using (TestDataContext db = new TestDataContext()) { TBL_TEST_TEST[] testRecords = new TBL_TEST_TEST[500000]; for (int count = 0; count < 500000; count++) { TBL_TEST_TEST testRecord = new TBL_TEST_TEST(); testRecord.NAME = "Name : " + count; testRecords[count] = testRecord; } StringBuilder sBuilder = new StringBuilder(); System.IO.StringWriter sWriter = new System.IO.StringWriter(sBuilder); XmlSerializer serializer = new XmlSerializer(typeof(TBL_TEST_TEST[])); serializer.Serialize(sWriter, testRecords); db.insertTestData(sBuilder.ToString()); } } So I like this because I get to use objects even though it is kinda redundant. I don't get how the SP works. Like I don't get the whole thing. I don't know if OPENXML has some batch insert under the hood but I do not even know how to take this example SP and change it to fit my tables since like I said I don't know what is going on. I also don't know what would happen if the object you have more tables in it. Like say I have a ProductName table what has a relationship to a Product table or something like that. In linq to sql you could get the product name object and make changes to the Product table in that same object. So I am not sure how to take that into account. I am not sure if I would have to do separate inserts or what. The time was pretty good for 500,000 records it took 52 seconds The last way of course was just using linq to do it all and it was pretty bad. /// <summary> /// This is using linq to sql to to insert lots of records. /// This way is slow as it uses no mass insert. /// Only tried to insert 50,000 records as I did not want to sit around till it did 500,000 records. /// http://www.codeproject.com/KB/linq/BulkOperations_LinqToSQL.aspx /// </summary> private static void LinqInsertAll() { using (TestDataContext db = new TestDataContext()) { db.CommandTimeout = 600; for (int count = 0; count < 50000; count++) { TBL_TEST_TEST testRecord = new TBL_TEST_TEST(); testRecord.NAME = "Name : " + count; db.TBL_TEST_TESTs.InsertOnSubmit(testRecord); } db.SubmitChanges(); } } I did only 50,000 records and that took over a minute to do. So I really narrowed it done to the linq to sql bulk insert way or bulk copy. I am just not sure how to do it when you have relationship for either way. I am not sure how they both stand up when doing updates instead of inserts as I have not gotten around to try it yet. I don't think I will ever need to insert/update more than 50,000 records at one type but at the same time I know I will have to do validation on records before inserting so that will slow it down and that sort of makes linq to sql nicer as your got objects especially if your first parsing data from a xml file before you insert into the database. Full C# code using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Xml.Serialization; using System.Data; using System.Data.SqlClient; namespace TestIQueryable { class Program { private static string connectionString = ""; static void Main(string[] args) { BatchInsert(); Console.WriteLine("done"); } /// <summary> /// This is using linq to sql to to insert lots of records. /// This way is slow as it uses no mass insert. /// Only tried to insert 50,000 records as I did not want to sit around till it did 500,000 records. /// http://www.codeproject.com/KB/linq/BulkOperations_LinqToSQL.aspx /// </summary> private static void LinqInsertAll() { using (TestDataContext db = new TestDataContext()) { db.CommandTimeout = 600; for (int count = 0; count < 50000; count++) { TBL_TEST_TEST testRecord = new TBL_TEST_TEST(); testRecord.NAME = "Name : " + count; db.TBL_TEST_TESTs.InsertOnSubmit(testRecord); } db.SubmitChanges(); } } /// <summary> /// This is using linq to sql to make the table objects. /// It is then serailzed to to an xml document and sent to a stored proedure /// that then does a bulk insert(I think with OpenXML) /// http://www.codeproject.com/KB/linq/BulkOperations_LinqToSQL.aspx /// </summary> private static void LinqInsertXMLBatch() { using (TestDataContext db = new TestDataContext()) { TBL_TEST_TEST[] testRecords = new TBL_TEST_TEST[500000]; for (int count = 0; count < 500000; count++) { TBL_TEST_TEST testRecord = new TBL_TEST_TEST(); testRecord.NAME = "Name : " + count; testRecords[count] = testRecord; } StringBuilder sBuilder = new StringBuilder(); System.IO.StringWriter sWriter = new System.IO.StringWriter(sBuilder); XmlSerializer serializer = new XmlSerializer(typeof(TBL_TEST_TEST[])); serializer.Serialize(sWriter, testRecords); db.insertTestData(sBuilder.ToString()); } } /// <summary> /// An ado.net 2.0 way to mass insert records. This seems to be the fastest. /// http://www.codeproject.com/KB/cs/MultipleInsertsIn1dbTrip.aspx#_Toc196622241 /// </summary> private static void BatchBulkCopy() { // Get the DataTable DataTable dtInsertRows = GetDataTable(); using (SqlBulkCopy sbc = new SqlBulkCopy(connectionString, SqlBulkCopyOptions.KeepIdentity)) { sbc.DestinationTableName = "TBL_TEST_TEST"; // Number of records to be processed in one go sbc.BatchSize = 500000; // Map the Source Column from DataTabel to the Destination Columns in SQL Server 2005 Person Table // sbc.ColumnMappings.Add("ID", "ID"); sbc.ColumnMappings.Add("NAME", "NAME"); // Number of records after which client has to be notified about its status sbc.NotifyAfter = dtInsertRows.Rows.Count; // Event that gets fired when NotifyAfter number of records are processed. sbc.SqlRowsCopied += new SqlRowsCopiedEventHandler(sbc_SqlRowsCopied); // Finally write to server sbc.WriteToServer(dtInsertRows); sbc.Close(); } } /// <summary> /// Another ado.net 2.0 way that uses a stored procedure to do a bulk insert. /// Seems slower then "BatchBulkCopy" way and it crashes when you try to insert 500,000 records in one go. /// http://www.codeproject.com/KB/cs/MultipleInsertsIn1dbTrip.aspx#_Toc196622241 /// </summary> private static void BatchInsert() { // Get the DataTable with Rows State as RowState.Added DataTable dtInsertRows = GetDataTable(); SqlConnection connection = new SqlConnection(connectionString); SqlCommand command = new SqlCommand("sp_BatchInsert", connection); command.CommandType = CommandType.StoredProcedure; command.UpdatedRowSource = UpdateRowSource.None; // Set the Parameter with appropriate Source Column Name command.Parameters.Add("@Name", SqlDbType.VarChar, 50, dtInsertRows.Columns[0].ColumnName); SqlDataAdapter adpt = new SqlDataAdapter(); adpt.InsertCommand = command; // Specify the number of records to be Inserted/Updated in one go. Default is 1. adpt.UpdateBatchSize = 500000; connection.Open(); int recordsInserted = adpt.Update(dtInsertRows); connection.Close(); } private static DataTable GetDataTable() { // You First need a DataTable and have all the insert values in it DataTable dtInsertRows = new DataTable(); dtInsertRows.Columns.Add("NAME"); for (int i = 0; i < 500000; i++) { DataRow drInsertRow = dtInsertRows.NewRow(); string name = "Name : " + i; drInsertRow["NAME"] = name; dtInsertRows.Rows.Add(drInsertRow); } return dtInsertRows; } static void sbc_SqlRowsCopied(object sender, SqlRowsCopiedEventArgs e) { Console.WriteLine("Number of records affected : " + e.RowsCopied.ToString()); } } }

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• data is not inserting in my db table [closed]

  - by Sarojit Chakraborty

  Please see my below(SubjectDetailsDao.java) code of addZoneToDb method. My debugger is nicely running upto ** session.getTransaction().commit();** code. but after that debugger stops,I do not know why it stops after that line? .And because of this i am unable to insert my data into my database table. I don't know what to do.Why it is not inserting my data into my database table? Plz help me for this. H Now i am getting this Error: Struts Problem Report Struts has detected an unhandled exception: Messages: org.hibernate.event.PreInsertEvent.getSource()Lorg/hibernate/event/EventSource; File: org/hibernate/validator/event/ValidateEventListener.java Line number: 172 Stacktraces java.lang.reflect.InvocationTargetException sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) java.lang.reflect.Method.invoke(Method.java:601) com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441) com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243) com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252) org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52) org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488) org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77) org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240) org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164) org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498) org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562) org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188) org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302) java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) java.lang.Thread.run(Thread.java:722) java.lang.NoSuchMethodError: org.hibernate.event.PreInsertEvent.getSource()Lorg/hibernate/event/EventSource; org.hibernate.validator.event.ValidateEventListener.onPreInsert(ValidateEventListener.java:172) org.hibernate.action.EntityInsertAction.preInsert(EntityInsertAction.java:156) org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:49) org.hibernate.engine.ActionQueue.execute(ActionQueue.java:250) org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:234) org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:141) org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:298) org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27) org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000) org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:338) org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106) v.esoft.dao.SubjectdetailsDAO.SubjectdetailsDAO.addZoneToDb(SubjectdetailsDAO.java:185) v.esoft.actions.LoginAction.datatobeinsert(LoginAction.java:53) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) java.lang.reflect.Method.invoke(Method.java:601) com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441) com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243) com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252) org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68) ............................... ............................... SubjectDetailsDao.java(I have problem in addZoneToDb) package v.esoft.dao.SubjectdetailsDAO; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import org.hibernate.HibernateException; import org.hibernate.Query; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.criterion.Order; import com.opensymphony.xwork2.ActionSupport; import v.esoft.connection.HibernateUtil; import v.esoft.pojos.Subjectdetails; public class SubjectdetailsDAO extends ActionSupport { private static Session session = null; private static SessionFactory sessionFactory = null; static Transaction transaction = null; private String currentDate; SimpleDateFormat formatter1 = new SimpleDateFormat("yyyy-MM-dd"); private java.util.Date currentdate; public SubjectdetailsDAO() { sessionFactory = HibernateUtil.getSessionFactory(); SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd"); currentdate = new java.util.Date(); currentDate = formatter.format(currentdate); } public List getAllCustomTempleteRoutinesForGrid() { List list = new ArrayList(); try { session = sessionFactory.openSession(); list = session.createCriteria(Subjectdetails.class).addOrder(Order.desc("subjectId")).list(); } catch (Exception e) { System.out.println("Exepetion in getAllCustomTempleteRoutines" + e); } finally { try { // HibernateUtil.shutdown(); } catch (Exception e) { System.out.println("Exception In getExerciseListByLoginId Resource closing :" + e); } } return list; } //**showing list on grid private static List<Subjectdetails> custLst=new ArrayList<Subjectdetails>(); static int total=50; static { SubjectdetailsDAO cts = new SubjectdetailsDAO(); Iterator iterator1 = cts.getAllCustomTempleteRoutinesForGrid().iterator(); while (iterator1.hasNext()) { Subjectdetails get = (Subjectdetails) iterator1.next(); custLst.add(get); } } /****************************************update Routines List by WorkId************************************/ public int updatesub(Subjectdetails s) { int updated = 0; try { session = sessionFactory.openSession(); transaction = session.beginTransaction(); Query query = session.createQuery("UPDATE Subjectdetails set subjectName = :routineName1 WHERE subjectId=:workoutId1"); query.setString("routineName1", s.getSubjectName()); query.setInteger("workoutId1", s.getSubjectId()); updated = query.executeUpdate(); if (updated != 0) { } transaction.commit(); } catch (Exception e) { if (transaction != null && transaction.isActive()) { try { transaction.rollback(); } catch (Exception e1) { System.out.println("Exception in addUser() Rollback :" + e1); } } } finally { try { session.flush(); session.close(); } catch (Exception e) { System.out.println("Exception In addUser Resource closing :" + e); } } return updated; } /****************************************update Routines List by WorkId************************************/ public int addSubjectt(Subjectdetails s) { int inserted = 0; Subjectdetails ss=new Subjectdetails(); try { session = sessionFactory.openSession(); transaction = session.beginTransaction(); ss. setSubjectName(s.getSubjectName()); session.save(ss); System.out.println("Successfully data insert in database"); inserted++; if (inserted != 0) { } transaction.commit(); } catch (Exception e) { if (transaction != null && transaction.isActive()) { try { transaction.rollback(); } catch (Exception e1) { System.out.println("Exception in addUser() Rollback :" + e1); } } } finally { try { session.flush(); session.close(); } catch (Exception e) { System.out.println("Exception In addUser Resource closing :" + e); } } return inserted; } /******************************************Get all Routines List by LoginID************************************/ public List getSubjects() { List list = null; try { session = sessionFactory.openSession(); list = session.createCriteria(Subjectdetails.class).list(); } catch (Exception e) { System.out.println("Exception in getRoutineList() :" + e); } finally { try { session.flush(); session.close(); } catch (Exception e) { System.out.println("Exception In getUserList Resource closing :" + e); } } return list; } //---\ public int addZoneToDb(String countryName, Integer loginId) { int inserted = 0; try { System.out.println("---------1--------"); Session session = HibernateUtil.getSessionFactory().openSession(); System.out.println("---------2------session--"+session); session.beginTransaction(); Subjectdetails country = new Subjectdetails(countryName, loginId, currentdate, loginId, currentdate); System.out.println("---------2------country--"+country); session.save(country); System.out.println("-------after save--"); inserted++; session.getTransaction().commit(); System.out.println("-------after commits--"); } catch (Exception e) { if (transaction != null && transaction.isActive()) { try { transaction.rollback(); } catch (Exception e1) { } } } finally { try { } catch (Exception e) { } } return inserted; } //-- public int nextId() { return total++; } public List<Subjectdetails> buildList() { return custLst; } public static int count() { return custLst.size(); } public static List<Subjectdetails> find(int o,int q) { return custLst.subList(o, q); } public void save(Subjectdetails c) { custLst.add(c); } public static Subjectdetails findById(Integer id) { try { for(Subjectdetails c:custLst) { if(c.getSubjectId()==id) { return c; } } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } return null; } public void update(Subjectdetails c) { for(Subjectdetails x:custLst) { if(x.getSubjectId()==c.getSubjectId()) { x.setSubjectName(c.getSubjectName()); } } } public void delete(Subjectdetails c) { custLst.remove(c); } public static List<Subjectdetails> findNotById(int id, int from,int to) { List<Subjectdetails> subLst=custLst.subList(from, to); List<Subjectdetails> temp=new ArrayList<Subjectdetails>(); for(Subjectdetails c:subLst) { if(c.getSubjectId()!=id) { temp.add(c); } } return temp; } public static List<Subjectdetails> findLesserAsId(int id, int from,int to) { List<Subjectdetails> subLst=custLst.subList(from, to); List<Subjectdetails> temp=new ArrayList<Subjectdetails>(); for(Subjectdetails c:subLst) { if(c.getSubjectId()<=id) { temp.add(c); } } return temp; } public static List<Subjectdetails> findGreaterAsId(int id, int from,int to) { List<Subjectdetails> subLst=custLst.subList(from, to); List<Subjectdetails> temp=new ArrayList<Subjectdetails>(); for(Subjectdetails c:subLst) { if(c.getSubjectId()>=id) { temp.add(c); } } return temp; } } Subjectdetails.hbm.xml <hibernate-mapping> <class name="vb.sofware.pojos.Subjectdetails" table="subjectdetails" catalog="vbsoftware"> <id name="subjectId" type="int"> <column name="subject_id" /> <generator class="increment"/> </id> <property name="subjectName" type="string"> <column name="subject_name" length="150" /> </property> <property name="createrId" type="java.lang.Integer"> <column name="creater_id" /> </property> <property name="createdDate" type="timestamp"> <column name="created_date" length="19" /> </property> <property name="updateId" type="java.lang.Integer"> <column name="update_id" /> </property> <property name="updatedDate" type="timestamp"> <column name="updated_date" length="19" /> </property> </class> </hibernate-mapping> My POJO - Subjectdetails.java package v.esoft.pojos; // Generated Oct 6, 2012 1:58:21 PM by Hibernate Tools 3.4.0.CR1 import java.util.Date; /** * Subjectdetails generated by hbm2java */ public class Subjectdetails implements java.io.Serializable { private int subjectId; private String subjectName; private Integer createrId; private Date createdDate; private Integer updateId; private Date updatedDate; public Subjectdetails( String subjectName) { //this.subjectId = subjectId; this.subjectName = subjectName; } public Subjectdetails() { } public Subjectdetails(int subjectId) { this.subjectId = subjectId; } public Subjectdetails(int subjectId, String subjectName, Integer createrId, Date createdDate, Integer updateId, Date updatedDate) { this.subjectId = subjectId; this.subjectName = subjectName; this.createrId = createrId; this.createdDate = createdDate; this.updateId = updateId; this.updatedDate = updatedDate; } public Subjectdetails( String subjectName, Integer createrId, Date createdDate, Integer updateId, Date updatedDate) { this.subjectName = subjectName; this.createrId = createrId; this.createdDate = createdDate; this.updateId = updateId; this.updatedDate = updatedDate; } public int getSubjectId() { return this.subjectId; } public void setSubjectId(int subjectId) { this.subjectId = subjectId; } public String getSubjectName() { return this.subjectName; } public void setSubjectName(String subjectName) { this.subjectName = subjectName; } public Integer getCreaterId() { return this.createrId; } public void setCreaterId(Integer createrId) { this.createrId = createrId; } public Date getCreatedDate() { return this.createdDate; } public void setCreatedDate(Date createdDate) { this.createdDate = createdDate; } public Integer getUpdateId() { return this.updateId; } public void setUpdateId(Integer updateId) { this.updateId = updateId; } public Date getUpdatedDate() { return this.updatedDate; } public void setUpdatedDate(Date updatedDate) { this.updatedDate = updatedDate; } } And my Sql query is CREATE TABLE IF NOT EXISTS `subjectdetails` ( `subject_id` int(3) NOT NULL, `subject_name` varchar(150) DEFAULT NULL, `creater_id` int(5) DEFAULT NULL, `created_date` datetime DEFAULT NULL, `update_id` int(5) DEFAULT NULL, `updated_date` datetime DEFAULT NULL, PRIMARY KEY (`subject_id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1;

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• MVC : Does Code to save data in cache or session belongs in controller?

  - by newbie

  I'm a bit confused if saving the information to session code below, belongs in the controller action as shown below or should it be part of my Model? I would add that I have other controller methods that will read this session value later. public ActionResult AddFriend(FriendsContext viewModel) { if (!ModelState.IsValid) { return View(viewModel); } // Start - Confused if the code block below belongs in Controller? Friend friend = new Friend(); friend.FirstName = viewModel.FirstName; friend.LastName = viewModel.LastName; friend.Email = viewModel.UserEmail; httpContext.Session["latest-friend"] = friend; // End Confusion return RedirectToAction("Home"); } I thought about adding a static utility class in my Model which does something like below, but it just seems stupid to add 2 lines of code in another file. public static void SaveLatestFriend(Friend friend, HttpContextBase httpContext) { httpContext.Session["latest-friend"] = friend; } public static Friend GetLatestFriend(HttpContextBase httpContext) { return httpContext.Session["latest-friend"] as Friend; }

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• Convert Dynamic to Type and convert Type to Dynamic

  - by Jon Canning

  public static class DynamicExtensions     {         public static T FromDynamic<T>(this IDictionary<string, object> dictionary)         {             var bindings = new List<MemberBinding>();             foreach (var sourceProperty in typeof(T).GetProperties().Where(x => x.CanWrite))             {                 var key = dictionary.Keys.SingleOrDefault(x => x.Equals(sourceProperty.Name, StringComparison.OrdinalIgnoreCase));                 if (string.IsNullOrEmpty(key)) continue;                 var propertyValue = dictionary[key];                 bindings.Add(Expression.Bind(sourceProperty, Expression.Constant(propertyValue)));             }             Expression memberInit = Expression.MemberInit(Expression.New(typeof(T)), bindings);             return Expression.Lambda<Func<T>>(memberInit).Compile().Invoke();         }         public static dynamic ToDynamic<T>(this T obj)         {             IDictionary<string, object> expando = new ExpandoObject();             foreach (var propertyInfo in typeof(T).GetProperties())             {                 var propertyExpression = Expression.Property(Expression.Constant(obj), propertyInfo);                 var currentValue = Expression.Lambda<Func<string>>(propertyExpression).Compile().Invoke();                 expando.Add(propertyInfo.Name.ToLower(), currentValue);             }             return expando as ExpandoObject;         }     }

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• Code Trivia #6

  - by João Angelo

  It’s time for yet another code trivia and it’s business as usual. What will the following program output to the console? using System; using System.Drawing; using System.Threading; class Program { [ThreadStatic] static Point Mark = new Point(1, 1); static void Main() { Thread.CurrentThread.Name = "A"; MoveMarkUp(); var helperThread = new Thread(MoveMarkUp) { Name = "B" }; helperThread.Start(); helperThread.Join(); } static void MoveMarkUp() { Mark.Y++; Console.WriteLine("{0}:{1}", Thread.CurrentThread.Name, Mark); } }

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• ResponseStatusLine protocol violation

  - by Tom Hines

  I parse/scrape a few web page every now and then and recently ran across an error that stated: "The server committed a protocol violation. Section=ResponseStatusLine".   After a few web searches, I found a couple of suggestions – one of which said the problem could be fixed by changing the HttpWebRequest ProtocolVersion to 1.0 with the command: 1: HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(strURI); 2: req.ProtocolVersion = HttpVersion.Version10;   …but that did not work in my particular case.   What DID work was the next suggestion I found that suggested the use of the setting: “useUnsafeHeaderParsing” either in the app.config file or programmatically. If added to the app.config, it would be: 1: <!-- after the applicationSettings --> 2: <system.net> 3: <settings> 4: <httpWebRequest useUnsafeHeaderParsing ="true"/> 5: </settings> 6: </system.net>   If done programmatically, it would look like this: C++: 1: // UUHP_CPP.h 2: #pragma once 3: using namespace System; 4: using namespace System::Reflection; 5:   6: namespace UUHP_CPP 7: { 8: public ref class CUUHP_CPP 9: { 10: public: 11: static bool UseUnsafeHeaderParsing(String^% strError) 12: { 13: Assembly^ assembly = Assembly::GetAssembly(System::Net::Configuration::SettingsSection::typeid); //__typeof 14: if (nullptr==assembly) 15: { 16: strError = "Could not access Assembly"; 17: return false; 18: } 19:   20: Type^ type = assembly->GetType("System.Net.Configuration.SettingsSectionInternal"); 21: if (nullptr==type) 22: { 23: strError = "Could not access internal settings"; 24: return false; 25: } 26:   27: Object^ obj = type->InvokeMember("Section", 28: BindingFlags::Static | BindingFlags::GetProperty | BindingFlags::NonPublic, 29: nullptr, nullptr, gcnew array<Object^,1>(0)); 30:   31: if(nullptr == obj) 32: { 33: strError = "Could not invoke Section member"; 34: return false; 35: } 36:   37: FieldInfo^ fi = type->GetField("useUnsafeHeaderParsing", BindingFlags::NonPublic | BindingFlags::Instance); 38: if(nullptr == fi) 39: { 40: strError = "Could not access useUnsafeHeaderParsing field"; 41: return false; 42: } 43:   44: if (!(bool)fi->GetValue(obj)) 45: { 46: fi->SetValue(obj, true); 47: } 48:   49: return true; 50: } 51: }; 52: } C# (CSharp): 1: using System; 2: using System.Reflection; 3:   4: namespace UUHP_CS 5: { 6: public class CUUHP_CS 7: { 8: public static bool UseUnsafeHeaderParsing(ref string strError) 9: { 10: Assembly assembly = Assembly.GetAssembly(typeof(System.Net.Configuration.SettingsSection)); 11: if (null == assembly) 12: { 13: strError = "Could not access Assembly"; 14: return false; 15: } 16:   17: Type type = assembly.GetType("System.Net.Configuration.SettingsSectionInternal"); 18: if (null == type) 19: { 20: strError = "Could not access internal settings"; 21: return false; 22: } 23:   24: object obj = type.InvokeMember("Section", 25: BindingFlags.Static | BindingFlags.GetProperty | BindingFlags.NonPublic, 26: null, null, new object[] { }); 27:   28: if (null == obj) 29: { 30: strError = "Could not invoke Section member"; 31: return false; 32: } 33:   34: // If it's not already set, set it. 35: FieldInfo fi = type.GetField("useUnsafeHeaderParsing", BindingFlags.NonPublic | BindingFlags.Instance); 36: if (null == fi) 37: { 38: strError = "Could not access useUnsafeHeaderParsing field"; 39: return false; 40: } 41:   42: if (!Convert.ToBoolean(fi.GetValue(obj))) 43: { 44: fi.SetValue(obj, true); 45: } 46:   47: return true; 48: } 49: } 50: }   F# (FSharp): 1: namespace UUHP_FS 2: open System 3: open System.Reflection 4: module CUUHP_FS = 5: let UseUnsafeHeaderParsing(strError : byref<string>) : bool = 6: // 7: let assembly : Assembly = Assembly.GetAssembly(typeof<System.Net.Configuration.SettingsSection>) 8: if (null = assembly) then 9: strError <- "Could not access Assembly" 10: false 11: else 12: 13: let myType : Type = assembly.GetType("System.Net.Configuration.SettingsSectionInternal") 14: if (null = myType) then 15: strError <- "Could not access internal settings" 16: false 17: else 18: 19: let obj : Object = myType.InvokeMember("Section", BindingFlags.Static ||| BindingFlags.GetProperty ||| BindingFlags.NonPublic, null, null, Array.zeroCreate 0) 20: if (null = obj) then 21: strError <- "Could not invoke Section member" 22: false 23: else 24: 25: // If it's not already set, set it. 26: let fi : FieldInfo = myType.GetField("useUnsafeHeaderParsing", BindingFlags.NonPublic ||| BindingFlags.Instance) 27: if(null = fi) then 28: strError <- "Could not access useUnsafeHeaderParsing field" 29: false 30: else 31: 32: if (not(Convert.ToBoolean(fi.GetValue(obj)))) then 33: fi.SetValue(obj, true) 34: 35: // Now return true 36: true VB (Visual Basic): 1: Option Explicit On 2: Option Strict On 3: Imports System 4: Imports System.Reflection 5:   6: Public Class CUUHP_VB 7: Public Shared Function UseUnsafeHeaderParsing(ByRef strError As String) As Boolean 8:   9: Dim assembly As [Assembly] 10: assembly = [assembly].GetAssembly(GetType(System.Net.Configuration.SettingsSection)) 11:   12: If (assembly Is Nothing) Then 13: strError = "Could not access Assembly" 14: Return False 15: End If 16:   17: Dim type As Type 18: type = [assembly].GetType("System.Net.Configuration.SettingsSectionInternal") 19: If (type Is Nothing) Then 20: strError = "Could not access internal settings" 21: Return False 22: End If 23:   24: Dim obj As Object 25: obj = [type].InvokeMember("Section", _ 26: BindingFlags.Static Or BindingFlags.GetProperty Or BindingFlags.NonPublic, _ 27: Nothing, Nothing, New [Object]() {}) 28:   29: If (obj Is Nothing) Then 30: strError = "Could not invoke Section member" 31: Return False 32: End If 33:   34: ' If it's not already set, set it. 35: Dim fi As FieldInfo 36: fi = [type].GetField("useUnsafeHeaderParsing", BindingFlags.NonPublic Or BindingFlags.Instance) 37: If (fi Is Nothing) Then 38: strError = "Could not access useUnsafeHeaderParsing field" 39: Return False 40: End If 41:   42: If (Not Convert.ToBoolean(fi.GetValue(obj))) Then 43: fi.SetValue(obj, True) 44: End If 45:   46: Return True 47: End Function 48: End Class   Technorati Tags: C++,CPP,VB,Visual Basic,F#,FSharp,C#,CSharp,ResponseStatusLine,protocol violation

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• Dynamic Tab Implementation in ADF

  - by Vijay Mohan

  Well, this can be a common usecase across apps to open tabs dynamically at runtime based on the request.Well, in order to achieve this you can have a parent container, lets say a panelTab component.Inside panelTab , u can have a showDetailItem inside an af:foreach or an af:iterator binded to a bean static list which will have as many show detail items as you wish to be shown.something like this.private static List = { new showDetailItem("1"),new ShowDetailItem("2") ...};now in the backing bean you can have a method that takes care of rendering and disclosing an specific tab based on the index.public void openMyTab(){List<MyItems> list = refToParentContainer.getChildren();int indexOfTabToBeOpened = //Write a method that will compute the tab index of the next //tab.list.get(index).setRendered(true);list.get(index).setDisclosed(true);similarly you can set other properties too.}Else, instead of having af:foreach/iterator iterating through the SD items , you can go for static SDs in the page with render property set to false and then you can follow the same approach to render/disclose it at runtime.

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• Why prefer a wildcard to a type discriminator in a Java API (Re: Effective Java)

  - by Michael Campbell

  In the generics section of Bloch's Effective Java (which handily is the "free" chapter available to all: http://java.sun.com/docs/books/effective/generics.pdf), he says: If a type parameter appears only once in a method declaration, replace it with a wildcard. (See page 31-33 of that pdf) The signature in question is: public static void swap(List<?> list, int i, int j) vs public static void swap(List<E> list, int i, int j) And then proceeds to use a static private "helper" function with an actual type parameter to perform the work. The helper function signature is EXACTLY that of the second option. Why is the wildcard preferable, since you need to NOT use a wildcard to get the work done anyway? I understand that in this case since he's modifying the List and you can't add to a collection with an unbounded wildcard, so why use it at all?

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• How can I host a website on a dynamically-assigned IP address?

  - by nick

  I recently upgraded my internet to the point that it is much faster and more reliable than my current webhost. I would like to move my current domain to be hosted at home, but my IP address is dynamic. As far as I know, I only get a new IP when I restart my modem and or router (which is almost never) or when cable one (my ISP) pushes out a firmware update (rarely). There are a few ways I can see doing this: Convince my ISP to give me a static IP Assign my router my current IP to force a static IP (which might work?) Set my DNS record to my current IP address and update it on the rare occasions that it changes. Obviously I'm hoping that the first one works, but I don't want to pay a lot of extra money (if that's what it takes) to get a static IP address. Which of these options will work most reliably?

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• SQL ADO.NET shortcut extensions (old school!)

  - by Jeff

  As much as I love me some ORM's (I've used LINQ to SQL quite a bit, and for the MSDN/TechNet Profile and Forums we're using NHibernate more and more), there are times when it's appropriate, and in some ways more simple, to just throw up so old school ADO.NET connections, commands, readers and such. It still feels like a pain though to new up all the stuff, make sure it's closed, blah blah blah. It's pretty much the least favorite task of writing data access code. To minimize the pain, I have a set of extension methods that I like to use that drastically reduce the code you have to write. Here they are... public static void Using(this SqlConnection connection, Action<SqlConnection> action) {     connection.Open();     action(connection);     connection.Close(); } public static SqlCommand Command(this SqlConnection connection, string sql){    var command = new SqlCommand(sql, connection);    return command;}public static SqlCommand AddParameter(this SqlCommand command, string parameterName, object value){    command.Parameters.AddWithValue(parameterName, value);    return command;}public static object ExecuteAndReturnIdentity(this SqlCommand command){    if (command.Connection == null)        throw new Exception("SqlCommand has no connection.");    command.ExecuteNonQuery();    command.Parameters.Clear();    command.CommandText = "SELECT @@IDENTITY";    var result = command.ExecuteScalar();    return result;}public static SqlDataReader ReadOne(this SqlDataReader reader, Action<SqlDataReader> action){    if (reader.Read())        action(reader);    reader.Close();    return reader;}public static SqlDataReader ReadAll(this SqlDataReader reader, Action<SqlDataReader> action){    while (reader.Read())        action(reader);    reader.Close();    return reader;} It has been awhile since I've really revisited these, so you will likely find opportunity for further optimization. The bottom line here is that you can chain together a bunch of these methods to make a much more concise database call, in terms of the code on your screen, anyway. Here are some examples: public Dictionary<string, string> Get(){    var dictionary = new Dictionary<string, string>();    _sqlHelper.GetConnection().Using(connection =>        connection.Command("SELECT Setting, [Value] FROM Settings")            .ExecuteReader()            .ReadAll(r => dictionary.Add(r.GetString(0), r.GetString(1))));    return dictionary;} or... public void ChangeName(User user, string newName){    _sqlHelper.GetConnection().Using(connection =>         connection.Command("UPDATE Users SET Name = @Name WHERE UserID = @UserID")            .AddParameter("@Name", newName)            .AddParameter("@UserID", user.UserID)            .ExecuteNonQuery());} The _sqlHelper.GetConnection() is just some other code that gets a connection object for you. You might have an even cleaner way to take that step out entirely. This looks more fluent, and the real magic sauce for me is the reader bits where you can put any kind of arbitrary method in there to iterate over the results.

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• creating a pre-menu level select screen

  - by Ephiras

  Hi I am working on creating a tower Defence java applet game and have come to a road block about implementing a title screen that i can select the level and difficulty of the rest of the game. my title screen class is called Menu. from this menu class i need to pass in many different variables into my Main class. i have used different classes before and know how to run them and such. but if both classes extend applet and each has its individual graphics method how can i run things from Main even though it was created in Menu. what i essentially want to do is run the Menu class withits action listeners and graphics until a Difficulty button has been selected, run the main class (which 100% works without having to have the Menu class) and pretty much terminate Menu so that i cannot go back to it, do not see its buttons or graphics menus. can i run one applet annd when i choose a button close that one and launch the other one? IF you would like to download the full project you can find it here, i had to comment out all the code that wasn't working my Menu class import java.awt.*; import java.awt.event.*; import java.applet.*; public class Menu extends Applet implements ActionListener{ Button bEasy,bMed,bHard; Main m; public void init(){ bEasy= new Button("Easy"); bEasy.setBounds(140,200,100,50); add(bEasy); bMed = new Button("Medium");bMed.setBounds(280,200,100,50); add(bMed); bHard= new Button("Hard");bHard.setBounds(420,200,100,50); add(bHard); setLayout(null); } public void actionPerformed(ActionEvent e){ Main m = new Main(20,10,3000,mapMed);//break; switch (e.getSource()){ case bEasy: Main m = new Main(6000,20,"levels/levelEasy.png");break;//enimies tower money world case bMed: Main m = new Main(4000,15,"levels/levelMed.png");break; case bHard: Main m = new Main(2000,10,"levels/levelEasy.png");break; default: break; } } public void paint(){ //m.draw(g) } } and here is my main class initialising code. import java.awt.*; import java.awt.event.*; import java.applet.*; import java.io.IOException; public class Main extends Applet implements Runnable, MouseListener, MouseMotionListener, ActionListener{ Button startButton, UpgRange, UpgDamage; //set up the buttons Color roadCol,startCol,finCol,selGrass,selRoad; //set up the colors Enemy e[][]; Tower t[]; Image towerpic,backpic,roadpic,levelPic; private Image i; private Graphics doubleG; //here is the world 0=grass 1=road 2=start 3=end int world[][],eStartX,eStartY; boolean drawMouse,gameEnd; static boolean start=false; static int gridLength=15; static int round=0; int Mx,My,timer=1500; static int sqrSize=31; int towers=0,towerSelected=-10; static int castleHealth=2000; String levelPath; //choose the level Easy Med or Hard int maxEnemy[] = {5,7,12,20,30,15,50,30,40,60};//number of enimies per round int maxTowers=15;//maximum number of towers allowed static int money =2000,damPrice=600,ranPrice=350,towerPrice=700; //money = the intial ammount of money you start of with //damPrice is the price to increase the damage of a tower //ranPrice is the price to increase the range of a tower public void main(int cH,int mT,int mo,int dP,int rP,int tP,String path,int[] mE)//constructor 1 castleHealth=cH; maxTowers=mT; money=mo; damPrice=dP; ranPrice=rP; towerPrice=tP; String levelPath=path; maxEnemy = mE; buildLevel(); } public void main(int cH,int mT,String path)//basic constructor castleHealth=cH; maxTowers=mT; String levelPath=path; maxEnemy = mE; buildLevel(); } public void init(){ setSize(sqrSize*15+200,sqrSize*15);//set the size of the screen roadCol = new Color(255,216,0);//set the colors for the different objects startCol = new Color(0,38,255); finCol = new Color(255,0,0); selRoad = new Color(242,204,155);//selColor is the color of something when your mouse hovers over it selGrass = new Color(0,190,0); roadpic = getImage(getDocumentBase(),"images/road.jpg"); towerpic = getImage(getDocumentBase(),"images/tower.png"); backpic = getImage(getDocumentBase(),"images/grass.jpg"); levelPic = getImage(getDocumentBase(),"images/level.jpg"); e= new Enemy[maxEnemy.length][];//activates all of the enimies for (int r=0;r<e.length;r++) e[r] = new Enemy[maxEnemy[r]]; t= new Tower[maxTowers]; for (int i=0;i<t.length;i++) t[i]= new Tower();//activates all the towers for (int i=0;i<e.length; i++)//sets all of the enimies starting co ordinates for (int j=0;j<e[i].length;j++) e[i][j] = new Enemy(eStartX,eStartY,world); initButtons();//initialise all the buttons addMouseMotionListener(this); addMouseListener(this); }

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• Solving 2D Collision Detection Issues with Relative Velocities

  - by Jengerer

  Imagine you have a situation where two objects are moving parallel to one-another and are both within range to collide with a static wall, like this: A common method used in dynamic collision detection is to loop through all objects in arbitrary order, solve for pair-wise collision detection using relative velocities, and then move the object to the nearest collision, if any. However, in this case, if the red object is checked first against the blue one, it would see that the relative velocity to the blue object is -20 m/s (and would thereby not collide this time frame). Then it would see that the red object would collide with the static wall, and the solution would be: And the red object passes through the blue one. So it appears to be a matter of choosing the right order in which you check collisions; but how can you determine which order is correct? How can this passing through of objects be avoided? Is ignoring relative velocity and considering every object as static during pair-wise checks a better idea for this reason?

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• Useful Extension Method for ICloneable

  - by DesigningCode

  In the past, I’ve had to put a type specific clone in each cloneable class, but with extension methods you can write a generic T specific clone class Program { static void Main(string[] args) { var b = new Blah() {X = 1, Y = 2}; var bb = b.Clone(); Console.WriteLine(string.Format("{0} {1}", bb.X, bb.Y)); } } public class Blah : ICloneable { public int X; public int Y; object ICloneable.Clone() { return MemberwiseClone(); } } public static class CloneExtension { public static T Clone<T>(this T o) where T : ICloneable { return (T)o.Clone(); } }

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• A Basic Thread

  - by Joe Mayo

  Most of the programs written are single-threaded, meaning that they run on the main execution thread. For various reasons such as performance, scalability, and/or responsiveness additional threads can be useful. .NET has extensive threading support, from the basic threads introduced in v1.0 to the Task Parallel Library (TPL) introduced in v4.0. To get started with threads, it's helpful to begin with the basics; starting a Thread. Why Do I Care? The scenario I'll use for needing to use a thread is writing to a file.  Sometimes, writing to a file takes a while and you don't want your user interface to lock up until the file write is done. In other words, you want the application to be responsive to the user. How Would I Go About It? The solution is to launch a new thread that performs the file write, allowing the main thread to return to the user right away.  Whenever the file writing thread completes, it will let the user know.  In the meantime, the user is free to interact with the program for other tasks. The following examples demonstrate how to do this. Show Me the Code? The code we'll use to work with threads is in the System.Threading namespace, so you'll need the following using directive at the top of the file: using System.Threading; When you run code on a thread, the code is specified via a method.  Here's the code that will execute on the thread: private static void WriteFile() { Thread.Sleep(1000); Console.WriteLine("File Written."); } The call to Thread.Sleep(1000) delays thread execution. The parameter is specified in milliseconds, and 1000 means that this will cause the program to sleep for approximately 1 second.  This method happens to be static, but that's just part of this example, which you'll see is launched from the static Main method.  A thread could be instance or static.  Notice that the method does not have parameters and does not have a return type. As you know, the way to refer to a method is via a delegate.  There is a delegate named ThreadStart in System.Threading that refers to a method without parameters or return type, shown below: ThreadStart fileWriterHandlerDelegate = new ThreadStart(WriteFile); I'll show you the whole program below, but the ThreadStart instance above goes in the Main method. The thread uses the ThreadStart instance, fileWriterHandlerDelegate, to specify the method to execute on the thread: Thread fileWriter = new Thread(fileWriterHandlerDelegate); As shown above, the argument type for the Thread constructor is the ThreadStart delegate type. The fileWriterHandlerDelegate argument is an instance of the ThreadStart delegate type. This creates an instance of a thread and what code will execute, but the new thread instance, fileWriter, isn't running yet. You have to explicitly start it, like this: fileWriter.Start(); Now, the code in the WriteFile method is executing on a separate thread. Meanwhile, the main thread that started the fileWriter thread continues on it's own.  You have two threads running at the same time. Okay, I'm Starting to Get Glassy Eyed. How Does it All Fit Together? The example below is the whole program, pulling all the previous bits together. It's followed by its output and an explanation. using System; using System.Threading; namespace BasicThread { class Program { static void Main() { ThreadStart fileWriterHandlerDelegate = new ThreadStart(WriteFile); Thread fileWriter = new Thread(fileWriterHandlerDelegate); Console.WriteLine("Starting FileWriter"); fileWriter.Start(); Console.WriteLine("Called FileWriter"); Console.ReadKey(); } private static void WriteFile() { Thread.Sleep(1000); Console.WriteLine("File Written"); } } } And here's the output: Starting FileWriter Called FileWriter File Written So, Why are the Printouts Backwards? The output above corresponds to Console.Writeline statements in the program, with the second and third seemingly reversed. In a single-threaded program, "File Written" would print before "Called FileWriter". However, this is a multi-threaded (2 or more threads) program.  In multi-threading, you can't make any assumptions about when a given thread will run.  In this case, I added the Sleep statement to the WriteFile method to greatly increase the chances that the message from the main thread will print first. Without the Thread.Sleep, you could run this on a system with multiple cores and/or multiple processors and potentially get different results each time. Interesting Tangent but What Should I Get Out of All This? Going back to the main point, launching the WriteFile method on a separate thread made the program more responsive.  The file writing logic ran for a while, but the main thread returned to the user, as demonstrated by the print out of "Called FileWriter".  When the file write finished, it let the user know via another print statement. This was a very efficient use of CPU resources that made for a more pleasant user experience. Joe

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• IsNullOrEmpty generic method for Array to avoid Re-Sharper warning

  - by Michael Freidgeim

  I’ve used the following extension method in many places. public static bool IsNullOrEmpty(this Object[] myArr) { return (myArr == null || myArr.Length == 0); }Recently I’ve noticed that Resharper shows warning covariant array conversion to object[] may cause an exception for the following codeObjectsOfMyClass.IsNullOrEmpty()I’ve resolved the issue by creating generic extension method public static bool IsNullOrEmpty<T>(this T[] myArr) { return (myArr == null || myArr.Length == 0); }Related linkshttp://connect.microsoft.com/VisualStudio/feedback/details/94089/add-isnullorempty-to-array-class    public static bool IsNullOrEmpty(this System.Collections.IEnumerable source)        {            if (source == null)                return true;            else            {                return !source.GetEnumerator().MoveNext();            }        }http://stackoverflow.com/questions/8560106/isnullorempty-equivalent-for-array-c-sharp

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• /etc/network/interfaces doesn't always take affect

  - by user1221444

  For some reason my eth0 does not have internet on reboot sometimes. I am using a static ip. I can ping my gateway, but I am unable to ping dns servers, or anything out of my network. It seems that when my internet does work(Usually but just restarting enough times), my /etc/resolv.conf has a nameserver in it. It is empty when I have no internet access. I believe something is overwriting my interfaces settings sometimes on boot. Any help would be appreciated. I am running Ubuntu Server 12.04 64bit /etc/network/interfaces: auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 173.213.192.234 netmask 255.255.255.248 network 173.213.192.232 broadcast 173.213.192.239 gateway 173.213.192.233 dns-nameservers 8.8.8.8 auto eth1 iface eth1 inet static address 10.0.0.106 netmask 255.255.255.0 gateway 10.0.0.1

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• Hosting a website from a dynamic IP

  - by nick

  I recently upgraded my internet to the point that it is much faster and more reliable than my current webhost. I would like to move my current domain to be hosted at home, but my IP address is dynamic. As far as I know, I only get a new IP when I restart my modem and or router (which is almost never) or when cable one (my ISP) pushes out a firmware update (rarely). There are a few ways I can see doing this 1) convince my ISP to give me a static IP 2) assign my router my current IP to force a static IP (which might work?) 3) set my dns record to my current IP address and update it on the rare occasions that it changes. Obviously I'm hoping that the first one works, but I don't want to pay a lot of extra money (if that's what it takes) to get a static IP address. Has anyone had any luck with something like that?

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• Euler Problem 20

  - by MarkPearl

  This was probably one of the easiest ones to complete – a quick bash got me the following… The Problem n! means n (n 1) ... 3 2 1 For example, 10! = 10 9 ... 3 2 1 = 3628800, and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27. Find the sum of the digits in the number 100! The Solution   private static BigInteger Factorial(int num) { if (num > 1) return (BigInteger)num * Factorial(num - 1); else return 1; } private static BigInteger SumDigits(string digits) { BigInteger result = 0; foreach (char number in digits) { result += Convert.ToInt32(number)-48; } return result; } static void Main(string[] args) { Console.WriteLine(SumDigits(Factorial(100).ToString())); Console.ReadLine(); }

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• Please help me to improve Re-Sharper

  - by TATWORTH

  Re-Sharper is an excellent aid to producing good code in either C# or VB.NET. Recently through using Resharper and StyleCop, I have found three area where ReSharper needs to be improved. Please log into the YouTrack at http://youtrack.jetbrains.net and vote for the following: RSRP-268868 Improvement to removal of redundant else and invert if optimisations for enhanced stylecop compliance. When Resharper removes a redundant else, there needs to be a blank line added. Currently there is no provision to specify this. Please vote for this! RSRP-272286 Resharper Feature Request to move initialisation to static constructor Currently ReSharper offers moving initialisation of of non-static variable to a constructor. Why not offer the same for a static constructor?  Please vote for this! RSRP-272285 Expansion of Switch Statement by Resharper Currently ReSharper will fill an empty switch statement based upon an enumeration but will not add missing enumeration values to such a switch statement.   Can't code withoutCoding assistance, smart code editing and code completion for C# and VB.NET

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• Use Extension Methods to find first and last day of the month

  - by Tim Hibbard

  A lot of reports work on data from last month.  It is a nice touch to have these dates pre-populated for your users.  Using extension methods, the code can look cleaner too. Extension Methods: public static class DateHelper { public static DateTime FirstOfTheMonth(this DateTime dt) { return new DateTime(dt.Year, dt.Month, 1); }   public static DateTime LastOfTheMonth(this DateTime dt) { return dt.FirstOfTheMonth().AddMonths(1).AddDays(-1); } } Consuming Code: void Prepopulate() { startDateBox.CurrentlySelectedDate = DateTime.Now.AddMonths(-1).FirstOfTheMonth(); endDateBox.CurrentlySelectedDate = DateTime.Now.AddMonths(-1).LastOfTheMonth(); }

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• Passing class names or objects?

  - by nischayn22

  I have a switch statement switch ( $id ) { case 'abc': return 'Animal'; case 'xyz': return 'Human'; //many more } I am returning class names,and use them to call some of their static functions using call_user_func(). Instead I can also create a object of that class, return that and then call the static function from that object as $object::method($param) switch ( $id ) { case 'abc': return new Animal; case 'xyz': return new Human; //many more } Which way is efficient? To make this question broader : I have classes that have mostly all static methods right now, putting them into classes is kind of a grouping idea here (for example the DB table structure of Animal is given by class Animal and so for Human class). I need to access many functions from these classes so the switch needs to give me access to the class

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• Where should I put a method that returns a list of active entries of a table?

  - by darga33

  I have a class named GuestbookEntry that maps to the properties that are in the database table named "guestbook". Very simple! Originally, I had a static method named getActiveEntries() that retrieved an array of all GuestbookEntry objects. Each row in the guestbook table was an object that was added to that array. Then while learning how to properly design PHP classes, I learned some things: Static methods are not desirable. Separation of Concerns Single Responsibility Principle If the GuestbookEntry class should only be responsible for managing single guestbook entries then where should this getActiveEntries() method most properly go? Update: I am looking for an answer that complies with the SOLID acronym principles and allows for test-ability. That's why I want to stay away from static calls/standard functions. DAO, repository, ...? Please explain as though your explanation will be part of "Where to Locate FOR DUMMIES"... :-)

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• Naming convention: field starting with "m" or "s"

  - by Noya

  Hope this question hasn't posted yet... I saw lot of code (for example some Android source code) where fields name start with a "m" while static fields start with "s" Example (taken from Android View class source): private SparseArray<Object> mKeyedTags; private static int sNextAccessibilityViewId; I was wondering what "m" and "s" stand for... maybe is "m" mutable and "s" static? Since it seems that is a largely adopted pattern do you know if there some literature about this kind of naming convention?

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