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  • Is it possible to write a generic +1 method for numeric box types in Java?

    - by polygenelubricants
    This is NOT homework. Part 1 Is it possible to write a generic method, something like this: <T extends Number> T plusOne(T num) { return num + 1; // DOESN'T COMPILE! How to fix??? } Short of using a bunch of instanceof and casts, is this possible? Part 2 The following 3 methods compile: Integer plusOne(Integer num) { return num + 1; } Double plusOne(Double num) { return num + 1; } Long plusOne(Long num) { return num + 1; } Is it possible to write a generic version that bound T to only Integer, Double, or Long?

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  • Is it possible to use the values method for a HashMap if the values are ArrayLists?

    - by Denman
    I'm stuck trying to get something to work in an assignment. I have a HashMap<Integer, ArrayList<Object>> called sharedLocks and I want to check whether a certain value can be found in any ArrayList in the HashMap. The following code obviously wouldn't work because Object[] can't be cast to ArrayList[], but it is a demonstration of the general functionality that I want. ArrayList[] values = (ArrayList[]) sharedLocks.values().toArray(); boolean valueExists = false; for (int i = 0; i < values.length; i++) { if (values[i].contains(accessedObject)) { valueExists = true; } } Is there a way for me to check every ArrayList in the HashMap for a certain value? I'm not sure how to use the values method for HashMaps in this case. Any help would be much appreciated.

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  • iPhone Simulator:Just show Default img and finish the delegate method appDidFinishLaunching after quit iPhone Simulator and rebuild...

    - by David_iDev
    Hi all, After I quit simulator and click build the app from XCode, the iPhone Simulator loading and my app will be install and run. But the app just show only Default image (finish the applicationDidFinishLaunching method - I logs it) and do nothing. I can't do anything in Simulator, event click the "Home" button of Simulator. But the other time, when Simulator already running, I select the "Build" button in XCode and everything is fine. Can you tell me why and how does this issue effect my app when I build it with real device? Thanks a lot!

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  • best method in jquery for replacing rows in a table after server side processing such as mysql sorti

    - by Kevin J
    What is the 'best practice' when returning dynamic data for a table (server side sorting, filtering etc from a db) ? Do you return just the data in json, and repeatedly clone a row element, replacing the values in each row (thus decreasing the size of the ajax call, but increasing the client side processing), or return the full html, and replace with .html or .append? Or is there another method I'm missing? This is a frequent situation in my app, and in some cases a bottleneck, and I am unsure if what I am doing is the best solution. Currently, I return the row html and use a single .append call, after emptying all the rows except the header.

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  • Why does FrameworkElement's FindResource() Method Accept an Object and not a String?

    - by ChrisNel52
    I understand that calling FindResource() on a FrameworkElement (e.g. a Window) can be used to find a resource in the FrameworkElement's ResourceDictionary. For example, I've used it many times to access a Style through code to add a new Setter to the Style dynamically. I always pass the x:Key value of the Style as a string into the FindResource() method. Like... Style style = w.FindResource("GridDescriptionColumn") as Style; My question is, I noticed that FindResource() accepts an argument of type object and not an argument of type string. I can't for the life of my think of a reason I would call FindResource() with an argument that is not a string. It makes me think that I may unaware of other ways to use FindResource(). Does anyone know why FindResource() accepts a parameter type of object and not string? If so, what would be an example of calling FindResource() with a parameter type other than a string? Thanks.

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  • What is the quikest method to see actual color of any hex code #a7a7a7?

    - by metal-gear-solid
    What is the quikest method to see actual color of any hex code #a7a7a7? When i work on other's CSS then if i deal with color codes then i quickly wan to see the color of that particular hex code. suppose if i'm editing css in notepad and i found code #a7a7a7 then how can i know what is the color of this code. If i have a color on my screen then i quickly know what would be hex code for this with the help of some tools ,but i need just opposite of this. i'm not talking about to see whole color chart of site. I want to see color of particular hex code.

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  • How to overcome case sensitive problem with contains method.??

    - by Srikanth
    Is there any solution to overcome case-sensitive problem for contains method. I have code like below string str = m_name; return avobj.Viewname.Contains(str); Eg: Welcome Here welcome here Both are same names but case is different. If I give 'W' in search box it is returning only 1st one. but I need both names display. I am storing the names in collection. And resultant values ( searched values ) are storing in List.

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  • Is it possible to pass arithmatic operators to a method in java?

    - by user349611
    Right now I'm going to have to write a method that looks like this: public String Calculate(String Operator, Double Operand1, Double Operand2) { if (Operator.equals("+")) { return String.valueOf(Operand1 + Operand2); } else if (Operator.equals("-")) { return String.valueOf(Operand1 - Operand2); } else if (Operator.equals("*")) { return String.valueOf(Operand1 * Operand2); } else { return "error..."; } } It would be nice if I could write the code more like this: public String Calculate(String Operator, Double Operand1, Double Operand2) { return String.valueOf(Operand1 Operator Operand2); } So Operator would replace the Arithmetic Operators (+, -, *, /...) Does anyone know if something like this is possible in java?

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  • How to get just free heap size (not together w stack/method mem) in Java?

    - by Pentium10
    I want to calculate the heap usage for my app. I would like to get a procent value of Heap size only. How do I get the value in code for the current running app? EDIT The upvoted answer is NOT complete/correct. The values returned by those methods include stack and method area too, and I need to monitor only heap size. With that code I got HeapError exception when I reached 43%, so I can't use those methods to monitor just heap.

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  • Is there a method I can override on a JavaScript object to control what is displayed by console.log?

    - by agnoster
    I'm thinking in particular of Chrome, though Firebug would be interesting to. I've tried toString() and valueOf(), but neither of those seem to be used. Interestingly, if I take a function it'll display the function definition - but then if I add a toString() method it will show null! var a = function(){}; console.log(a); // output: function (){} a.toString = function(){ return 'a'; }; console.log(a); // output: null a.valueOf = function(){ return 'v'; }; console.log(a); // output: null Any ideas?

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  • How does ruby allow a method and a Class with the same name?

    - by Daniel Beardsley
    I happened to be working on a Singleton class in ruby and just remembered the way it works in factory_girl. They worked it out so you can use both the long way Factory.create(...) and the short way Factory(...) I thought about it and was curious to see how they made the class Factory also behave like a method. They simply used Factory twice like so: def Factory (args) ... end class Factory ... end My Question is: How does ruby accomplish this? and Is there danger in using this seemingly quirky pattern?

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  • Is a VPN a good method for protecting data in an untrusted network? [closed]

    - by john
    I will be connecting my laptop in an untrusted network. If I setup OpenVpn on a server and use a vpn client on the laptop to connect through it, is it enough? Can someone perform a MITM attack or otherwise eavesdrop on my traffic? If someone on the local network port-scans my laptop, will the open ports be accessible to him while I use the VPN tunnel? Is there anything else I should keep in mind?

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  • Java inheritance question

    - by user247866
    So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = method-call();` // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't want to duplicate it. I want to have one method that takes as input an instance of class A, as follows: public void some-method(LIst<A> a) However, when I do: C c = new C(). c. some-method(b) I get an error that some-method is not applicable for the argument List, instead it's expecting to get List. Is there a good way to fix this problem? Many thanks!

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  • Where does the 'method' implementation go? (I'm a newbie)

    - by Spokane-Dude
    I have this code: #import "SQLiteDB.h" @implementation SQLiteDB @synthesize db, dbPath, databaseKey; @end //-------------- check for database or create it ----------------| - (void)checkForDatabase { NSFileManager *filemanager = [NSFileManager defaultManager]; NSString *databasePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingString:@"/ppcipher.s3db"]; if(![filemanager fileExistsAtPath:databasePath]) { //Database doesn't exist yet, so we create it... NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingString:@"/ppcipher.s3db"]; sqlite3 *db; if(sqlite3_open(databasePath, db) == SQLITE_OK) { } } } It's complaining that "method definition not in @implementation context". So where does it go? (I tried in the .h file, but still get the error)

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  • What is the difference between "render a view" and send the response using the Response's method "sendResponse()"?

    - by Green
    I've asked a question about what is "rendering a view". Got some answers: Rendering a view means showing up a View eg html part to user or browser. and So by rendering a view, the MVC framework has handled the data in the controller and done the backend work in the model, and then sends that data to the View to be output to the user. and render just means to emit. To print. To echo. To write to some source (probably stdout). but don't understand then the difference between rendering a view and using the Response class to send the output to the user using its sendResponse() method. If render a view means to echo the output to the user then why sendResponse() exists and vise versa? sendResponse() exactly sends headers and after headers outputs the body. They solve the same tasks but differently? What is the difference?

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  • Loose Coupling in Object Oriented Design

    - by m3th0dman
    I am trying to learn GRASP and I found this explained (here on page 3) about Low Coupling and I was very surprised when I found this: Consider the method addTrack for an Album class, two possible methods are: addTrack( Track t ) and addTrack( int no, String title, double duration ) Which method reduces coupling? The second one does, since the class using the Album class does not have to know a Track class. In general, parameters to methods should use base types (int, char ...) and classes from the java.* packages. I tend to diasgree with this; I believe addTrack(Track t) is better than addTrack(int no, String title, double duration) due to various reasons: It is always better for a method to as fewer parameters as possible (according to Uncle Bob's Clean Code none or one preferably, 2 in some cases and 3 in special cases; more than 3 needs refactoring - these are of course recommendations not holly rules). If addTrack is a method of an interface, and the requirements need that a Track should have more information (say year or genre) then the interface needs to be changed and so that the method should supports another parameter. Encapsulation is broke; if addTrack is in an interface, then it should not know the internals of the Track. It is actually more coupled in the second way, with many parameters. Suppose the no parameter needs to be changed from int to long because there are more than MAX_INT tracks (or for whatever reason); then both the Track and the method need to be changed while if the method would be addTrack(Track track) only the Track would be changed. All the 4 arguments are actually connected with each other, and some of them are consequences from others. Which approach is better?

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  • Error in code of basic game using multiple sprites and surfaceView [on hold]

    - by Khagendra Nath Mahato
    I am a beginner to android and i was trying to make a basic game with the help of an online video tutorial. I am having problem with the multi-sprites and how to use with surfaceview.The application fails launching. Here is the code of the game.please help me. package com.example.killthemall; import java.util.ArrayList; import java.util.List; import java.util.Random; import android.app.Activity; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Rect; import android.os.Bundle; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.widget.Toast; public class Game extends Activity { KhogenView View1; @Override protected void onPause() { // TODO Auto-generated method stub super.onPause(); while(true){ try { OurThread.join(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); }} } Thread OurThread; int herorows = 4; int herocolumns = 3; int xpos, ypos; int xspeed; int yspeed; int herowidth; int widthnumber = 0; int heroheight; Rect src; Rect dst; int round; Bitmap bmp1; // private Bitmap bmp1;//change name public List<Sprite> sprites = new ArrayList<Sprite>() { }; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); View1 = new KhogenView(this); setContentView(View1); sprites.add(createSprite(R.drawable.image)); sprites.add(createSprite(R.drawable.bad1)); sprites.add(createSprite(R.drawable.bad2)); sprites.add(createSprite(R.drawable.bad3)); sprites.add(createSprite(R.drawable.bad4)); sprites.add(createSprite(R.drawable.bad5)); sprites.add(createSprite(R.drawable.bad6)); sprites.add(createSprite(R.drawable.good1)); sprites.add(createSprite(R.drawable.good2)); sprites.add(createSprite(R.drawable.good3)); sprites.add(createSprite(R.drawable.good4)); sprites.add(createSprite(R.drawable.good5)); sprites.add(createSprite(R.drawable.good6)); } private Sprite createSprite(int image) { // TODO Auto-generated method stub bmp1 = BitmapFactory.decodeResource(getResources(), image); return new Sprite(this, bmp1); } public class KhogenView extends SurfaceView implements Runnable { SurfaceHolder OurHolder; Canvas canvas = null; Random rnd = new Random(); { xpos = rnd.nextInt(canvas.getWidth() - herowidth)+herowidth; ypos = rnd.nextInt(canvas.getHeight() - heroheight)+heroheight; xspeed = rnd.nextInt(10 - 5) + 5; yspeed = rnd.nextInt(10 - 5) + 5; } public KhogenView(Context context) { super(context); // TODO Auto-generated constructor stub OurHolder = getHolder(); OurThread = new Thread(this); OurThread.start(); } @Override public void run() { // TODO Auto-generated method stub herowidth = bmp1.getWidth() / 3; heroheight = bmp1.getHeight() / 4; boolean isRunning = true; while (isRunning) { if (!OurHolder.getSurface().isValid()) continue; canvas = OurHolder.lockCanvas(); canvas.drawRGB(02, 02, 50); for (Sprite sprite : sprites) { if (widthnumber == 3) widthnumber = 0; update(); getdirection(); src = new Rect(widthnumber * herowidth, round * heroheight, (widthnumber + 1) * herowidth, (round + 1)* heroheight); dst = new Rect(xpos, ypos, xpos + herowidth, ypos+ heroheight); canvas.drawBitmap(bmp1, src, dst, null); } widthnumber++; OurHolder.unlockCanvasAndPost(canvas); } } public void update() { try { Thread.sleep(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } if (xpos + xspeed <= 0) xspeed = 40; if (xpos >= canvas.getWidth() - herowidth) xspeed = -50; if (ypos + yspeed <= 0) yspeed = 45; if (ypos >= canvas.getHeight() - heroheight) yspeed = -55; xpos = xpos + xspeed; ypos = ypos + yspeed; } public void getdirection() { double angleinteger = (Math.atan2(yspeed, xspeed)) / (Math.PI / 2); round = (int) (Math.round(angleinteger) + 2) % herorows; // Toast.makeText(this, String.valueOf(round), // Toast.LENGTH_LONG).show(); } } public class Sprite { Game game; private Bitmap bmp; public Sprite(Game game, Bitmap bmp) { // TODO Auto-generated constructor stub this.game = game; this.bmp = bmp; } } } Here is the LogCat if it helps.... 08-22 23:18:06.980: D/AndroidRuntime(28151): Shutting down VM 08-22 23:18:06.980: W/dalvikvm(28151): threadid=1: thread exiting with uncaught exception (group=0xb3f6f4f0) 08-22 23:18:06.980: D/AndroidRuntime(28151): procName from cmdline: com.example.killthemall 08-22 23:18:06.980: E/AndroidRuntime(28151): in writeCrashedAppName, pkgName :com.example.killthemall 08-22 23:18:06.980: D/AndroidRuntime(28151): file written successfully with content: com.example.killthemall StringBuffer : ;com.example.killthemall 08-22 23:18:06.990: I/Process(28151): Sending signal. PID: 28151 SIG: 9 08-22 23:18:06.990: E/AndroidRuntime(28151): FATAL EXCEPTION: main 08-22 23:18:06.990: E/AndroidRuntime(28151): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.killthemall/com.example.killthemall.Game}: java.lang.NullPointerException 08-22 23:18:06.990: E/AndroidRuntime(28151): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 08-22 23:18:06.990: E/AndroidRuntime(28151): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 08-22 23:18:06.990: E/AndroidRuntime(28151): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 08-22 23:18:06.990: E/AndroidRuntime(28151): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 08-22 23:18:06.990: E/AndroidRuntime(28151): at android.os.Handler.dispatchMessage(Handler.java:99) 08-22 23:18:06.990: E/AndroidRuntime(28151): at android.os.Looper.loop(Looper.java:130) 08-22 23:18:06.990: E/AndroidRuntime(28151): at android.app.ActivityThread.main(ActivityThread.java:3683) 08-22 23:18:06.990: E/AndroidRuntime(28151): at java.lang.reflect.Method.invokeNative(Native Method) 08-22 23:18:06.990: E/AndroidRuntime(28151): at java.lang.reflect.Method.invoke(Method.java:507) 08-22 23:18:06.990: E/AndroidRuntime(28151): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:880) 08-22 23:18:06.990: E/AndroidRuntime(28151): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:638) 08-22 23:18:06.990: E/AndroidRuntime(28151): at dalvik.system.NativeStart.main(Native Method) 08-22 23:18:06.990: E/AndroidRuntime(28151): Caused by: java.lang.NullPointerException 08-22 23:18:06.990: E/AndroidRuntime(28151): at com.example.killthemall.Game$KhogenView.<init>(Game.java:96) 08-22 23:18:06.990: E/AndroidRuntime(28151): at com.example.killthemall.Game.onCreate(Game.java:58) 08-22 23:18:06.990: E/AndroidRuntime(28151): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 08-22 23:18:06.990: E/AndroidRuntime(28151): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 08-22 23:18:06.990: E/AndroidRuntime(28151): ... 11 more 08-22 23:18:18.050: D/AndroidRuntime(28191): Shutting down VM 08-22 23:18:18.050: W/dalvikvm(28191): threadid=1: thread exiting with uncaught exception (group=0xb3f6f4f0) 08-22 23:18:18.050: I/Process(28191): Sending signal. PID: 28191 SIG: 9 08-22 23:18:18.050: D/AndroidRuntime(28191): procName from cmdline: com.example.killthemall 08-22 23:18:18.050: E/AndroidRuntime(28191): in writeCrashedAppName, pkgName :com.example.killthemall 08-22 23:18:18.050: D/AndroidRuntime(28191): file written successfully with content: com.example.killthemall StringBuffer : ;com.example.killthemall 08-22 23:18:18.050: E/AndroidRuntime(28191): FATAL EXCEPTION: main 08-22 23:18:18.050: E/AndroidRuntime(28191): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.killthemall/com.example.killthemall.Game}: java.lang.NullPointerException 08-22 23:18:18.050: E/AndroidRuntime(28191): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 08-22 23:18:18.050: E/AndroidRuntime(28191): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 08-22 23:18:18.050: E/AndroidRuntime(28191): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 08-22 23:18:18.050: E/AndroidRuntime(28191): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 08-22 23:18:18.050: E/AndroidRuntime(28191): at android.os.Handler.dispatchMessage(Handler.java:99) 08-22 23:18:18.050: E/AndroidRuntime(28191): at android.os.Looper.loop(Looper.java:130) 08-22 23:18:18.050: E/AndroidRuntime(28191): at android.app.ActivityThread.main(ActivityThread.java:3683) 08-22 23:18:18.050: E/AndroidRuntime(28191): at java.lang.reflect.Method.invokeNative(Native Method) 08-22 23:18:18.050: E/AndroidRuntime(28191): at java.lang.reflect.Method.invoke(Method.java:507) 08-22 23:18:18.050: E/AndroidRuntime(28191): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:880) 08-22 23:18:18.050: E/AndroidRuntime(28191): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:638) 08-22 23:18:18.050: E/AndroidRuntime(28191): at dalvik.system.NativeStart.main(Native Method) 08-22 23:18:18.050: E/AndroidRuntime(28191): Caused by: java.lang.NullPointerException 08-22 23:18:18.050: E/AndroidRuntime(28191): at com.example.killthemall.Game$KhogenView.<init>(Game.java:96) 08-22 23:18:18.050: E/AndroidRuntime(28191): at com.example.killthemall.Game.onCreate(Game.java:58) 08-22 23:18:18.050: E/AndroidRuntime(28191): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 08-22 23:18:18.050: E/AndroidRuntime(28191): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 08-22 23:18:18.050: E/AndroidRuntime(28191): ... 11 more

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  • SQL SERVER – Three Methods to Insert Multiple Rows into Single Table – SQL in Sixty Seconds #024 – Video

    - by pinaldave
    One of the biggest ask I have always received from developers is that if there is any way to insert multiple rows into a single table in a single statement. Currently when developers have to insert any value into the table they have to write multiple insert statements. First of all this is not only boring it is also very much time consuming as well. Additionally, one has to repeat the same syntax so many times that the word boring becomes an understatement. In the following quick video we have demonstrated three different methods to insert multiple values into a single table. -- Insert Multiple Values into SQL Server CREATE TABLE #SQLAuthority (ID INT, Value VARCHAR(100)); Method 1: Traditional Method of INSERT…VALUE -- Method 1 - Traditional Insert INSERT INTO #SQLAuthority (ID, Value) VALUES (1, 'First'); INSERT INTO #SQLAuthority (ID, Value) VALUES (2, 'Second'); INSERT INTO #SQLAuthority (ID, Value) VALUES (3, 'Third'); Clean up -- Clean up TRUNCATE TABLE #SQLAuthority; Method 2: INSERT…SELECT -- Method 2 - Select Union Insert INSERT INTO #SQLAuthority (ID, Value) SELECT 1, 'First' UNION ALL SELECT 2, 'Second' UNION ALL SELECT 3, 'Third'; Clean up -- Clean up TRUNCATE TABLE #SQLAuthority; Method 3: SQL Server 2008+ Row Construction -- Method 3 - SQL Server 2008+ Row Construction INSERT INTO #SQLAuthority (ID, Value) VALUES (1, 'First'), (2, 'Second'), (3, 'Third'); Clean up -- Clean up DROP TABLE #SQLAuthority; Related Tips in SQL in Sixty Seconds: SQL SERVER – Insert Multiple Records Using One Insert Statement – Use of UNION ALL SQL SERVER – 2008 – Insert Multiple Records Using One Insert Statement – Use of Row Constructor I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. If we like your idea we promise to share with you educational material. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video

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  • A Simple Approach For Presenting With Code Samples

    - by Jesse Taber
    Originally posted on: http://geekswithblogs.net/GruffCode/archive/2013/07/31/a-simple-approach-for-presenting-with-code-samples.aspxI’ve been getting ready for a presentation and have been struggling a bit with the best way to show and execute code samples. I don’t present often (hardly ever), but when I do I like the presentation to have a lot of succinct and executable code snippets to help illustrate the points that I’m making. Depending on what the presentation is about, I might just want to build an entire sample application that I would run during the presentation. In other cases, however, building a full-blown application might not really be the best way to present the code. The presentation I’m working on now is for an open source utility library for dealing with dates and times. I could have probably cooked up a sample app for accepting date and time input and then contrived ways in which it could put the library through its paces, but I had trouble coming up with one app that would illustrate all of the various features of the library that I wanted to highlight. I finally decided that what I really needed was an approach that met the following criteria: Simple: I didn’t want the user interface or overall architecture of a sample application to serve as a distraction from the demonstration of the syntax of the library that the presentation is about. I want to be able to present small bits of code that are focused on accomplishing a single task. Several of these examples will look similar, and that’s OK. I want each sample to “stand on its own” and not rely much on external classes or methods (other than the library that is being presented, of course). “Debuggable” (not really a word, I know): I want to be able to easily run the sample with the debugger attached in Visual Studio should I want to step through any bits of code and show what certain values might be at run time. As far as I know this rules out something like LinqPad, though using LinqPad to present code samples like this is actually a very interesting idea that I might explore another time. Flexible and Selectable: I’m going to have lots of code samples to show, and I want to be able to just package them all up into a single project or module and have an easy way to just run the sample that I want on-demand. Since I’m presenting on a .NET framework library, one of the simplest ways in which I could execute some code samples would be to just create a Console application and use Console.WriteLine to output the pertinent info at run time. This gives me a “no frills” harness from which to run my code samples, and I just hit ‘F5’ to run it with the debugger. This satisfies numbers 1 and 2 from my list of criteria above, but item 3 is a little harder. By default, just running a console application is going to execute the ‘main’ method, and then terminate the program after all code is executed. If I want to have several different code samples and run them one at a time, it would be cumbersome to keep swapping the code I want in and out of the ‘main’ method of the console application. What I really want is an easy way to keep the console app running throughout the whole presentation and just have it run the samples I want when I want. I could setup a simple Windows Forms or WPF desktop application with buttons for the different samples, but then I’m getting away from my first criteria of keeping things as simple as possible. Infinite Loops To The Rescue I found a way to have a simple console application satisfy all three of my requirements above, and it involves using an infinite loop and some Console.ReadLine calls that will give the user an opportunity to break out and exit the program. (All programs that need to run until they are closed explicitly (or crash!) likely use similar constructs behind the scenes. Create a new Windows Forms project, look in the ‘Program.cs’ that gets generated, and then check out the docs for the Application.Run method that it calls.). Here’s how the main method might look: 1: static void Main(string[] args) 2: { 3: do 4: { 5: Console.Write("Enter command or 'exit' to quit: > "); 6: var command = Console.ReadLine(); 7: if ((command ?? string.Empty).Equals("exit", StringComparison.OrdinalIgnoreCase)) 8: { 9: Console.WriteLine("Quitting."); 10: break; 11: } 12: 13: } while (true); 14: } The idea here is the app prompts me for the command I want to run, or I can type in ‘exit’ to break out of the loop and let the application close. The only trick now is to create a set of commands that map to each of the code samples that I’m going to want to run. Each sample is already encapsulated in a single public method in a separate class, so I could just write a big switch statement or create a hashtable/dictionary that maps command text to an Action that will invoke the proper method, but why re-invent the wheel? CLAP For Your Own Presentation I’ve blogged about the CLAP library before, and it turns out that it’s a great fit for satisfying criteria #3 from my list above. CLAP lets you decorate methods in a class with an attribute and then easily invoke those methods from within a console application. CLAP was designed to take the arguments passed into the console app from the command line and parse them to determine which method to run and what arguments to pass to that method, but there’s no reason you can’t re-purpose it to accept command input from within the infinite loop defined above and invoke the corresponding method. Here’s how you might define a couple of different methods to contain two different code samples that you want to run during your presentation: 1: public static class CodeSamples 2: { 3: [Verb(Aliases="one")] 4: public static void SampleOne() 5: { 6: Console.WriteLine("This is sample 1"); 7: } 8:   9: [Verb(Aliases="two")] 10: public static void SampleTwo() 11: { 12: Console.WriteLine("This is sample 2"); 13: } 14: } A couple of things to note about the sample above: I’m using static methods. You don’t actually need to use static methods with CLAP, but the syntax ends up being a bit simpler and static methods happen to lend themselves well to the “one self-contained method per code sample” approach that I want to use. The methods are decorated with a ‘Verb’ attribute. This tells CLAP that they are eligible targets for commands. The “Aliases” argument lets me give them short and easy-to-remember aliases that can be used to invoke them. By default, CLAP just uses the full method name as the command name, but with aliases you can simply the usage a bit. I’m not using any parameters. CLAP’s main feature is its ability to parse out arguments from a command line invocation of a console application and automatically pass them in as parameters to the target methods. My code samples don’t need parameters ,and honestly having them would complicate giving the presentation, so this is a good thing. You could use this same approach to invoke methods with parameters, but you’d have a couple of things to figure out. When you invoke a .NET application from the command line, Windows will parse the arguments and pass them in as a string array (called ‘args’ in the boilerplate console project Program.cs). The parsing that gets done here is smart enough to deal with things like treating strings in double quotes as one argument, and you’d have to re-create that within your infinite loop if you wanted to use parameters. I plan on either submitting a pull request to CLAP to add this capability or maybe just making a small utility class/extension method to do it and posting that here in the future. So I now have a simple class with static methods to contain my code samples, and an infinite loop in my ‘main’ method that can accept text commands. Wiring this all up together is pretty easy: 1: static void Main(string[] args) 2: { 3: do 4: { 5: try 6: { 7: Console.Write("Enter command or 'exit' to quit: > "); 8: var command = Console.ReadLine(); 9: if ((command ?? string.Empty).Equals("exit", StringComparison.OrdinalIgnoreCase)) 10: { 11: Console.WriteLine("Quitting."); 12: break; 13: } 14:   15: Parser.Run<CodeSamples>(new[] { command }); 16: Console.WriteLine("---------------------------------------------------------"); 17: } 18: catch (Exception ex) 19: { 20: Console.Error.WriteLine("Error: " + ex.Message); 21: } 22:   23: } while (true); 24: } Note that I’m now passing the ‘CodeSamples’ class into the CLAP ‘Parser.Run’ as a type argument. This tells CLAP to inspect that class for methods that might be able to handle the commands passed in. I’m also throwing in a little “----“ style line separator and some basic error handling (because I happen to know that some of the samples are going to throw exceptions for demonstration purposes) and I’m good to go. Now during my presentation I can just have the console application running the whole time with the debugger attached and just type in the alias of the code sample method that I want to run when I want to run it.

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  • Using Exception Handler in an ADF Task Flow

    - by anmprs
    Problem Statement: Exception thrown in a task flow gets wrapped in an exception that gives an unintelligible error message to the user. Figure 1 Solution 1. Over-writing the error message with a user-friendly error message. Figure 2 Steps to code 1. Generating an exception: Write a method that throws an exception and drop it in the task flow.2. Adding an Exception Handler: Write a method (example below) to overwrite the Error in the bean or data control and drop the method in the task flow. Figure 3 This method is marked as the Exception Handler by Right-Click on method > Mark Activity> Exception Handler or by the button that is displayed in this screenshot Figure 4 The Final task flow should look like this. This will overwrite the exception with the error message in figure 2. Note: There is no need for a control flow between the two method calls (as shown below). Figure 5 Solution 2: Re-Routing the task flow to display an error page Figure 6 Steps to code 1. This is the same as step 1 of solution 1.2. Adding an Exception Handler: The Exception handler is not always a method; in this case it is implemented on a task flow return.  The task flow looks like this. Figure 7 In the figure below you will notice that the task flow return points to a control flow ‘error’ in the calling task flow. Figure 8 This control flow in turn goes to a view ‘error.jsff’ which contains the error message that one wishes to display.  This can be seen in the figure below. (‘withErrorHandling’ is a  call to the task flow in figure 7) Figure 9

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  • What are the best practices for phasing out obsolete code?

    - by P.Brian.Mackey
    I have the need to phase out an obsolete method. I am aware of the [Obsolete] attribute. Does Microsoft have a recommended best practice guide for doing this? Here's my current plan: A. I do not want to create a new assembly because developers would have to add a new reference to their projects and I expect to get a lot of grief from my boss and co-workers if they must do this. We also do not maintain multiple assembly versions. We only use the latest version. Changing this practice would require changing our deployment process which is a big issue (have to teach people how to do things with TFS instead of FinalBuilder and get them to give up FinalBuilder) B. Mark the old method obsolete. C. Because the implementation is changing (not the method signature), I need to rename the method rather than create an overload. So, to make users aware of the proper method I plan to add a message to the [Obsolete] attribute. This part bothers me, because the only change I'm making is decoupling the method from the connection string. But, because I'm not adding a new assembly, I see no way around this. Result: [Obsolete("Please don't use this anymore because it does not implement IMyDbProvider. Use XXX instead.")]; /// <summary> /// /// </summary> /// <param name="settingName"></param> /// <returns></returns> public static Dictionary<string, Setting> ReadSettings(string settingName) { return ReadSettings(settingName, SomeGeneralClass.ConnectionString); } public Dictionary<string, Setting> ReadSettings2(string settingName) { return ReadSettings(settingName);// IMyDbProvider.ConnectionString private member added to class. Probably have to make this an instance method. }

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  • EJB Persist On Master Child Relationship

    - by deepak.siddappa(at)oracle.com
    Let us take scenario where in users wants to persist master child relationship. Here will have two tables dept, emp (using Scott Schema) which are having master child relation.Model Diagram: Here in the above model diagram, Dept is the Master table and Emp is child table and Dept is related to emp by one to n relationship. Lets assume we need to make new entries in emp table using EJB persist method. Create a Emp form manually dropping the fields, where deptno will be dropped as Single Selection -> ADF Select One Choice (which is a foreign key in emp table) from deptFindAll DC. Make sure to bind all field variables in backing bean.Employee Form:Once the Emp form created, If the persistEmp() method is used to commit the record this will persist all the Emp fields into emp table except deptno, because the deptno will be passed as a Object reference in persistEmp method  (Its foreign key reference). So directly deptno can't be passed to the persistEmp method instead deptno should be explicitly set to the emp object, then the persist will save the deptno to the emp table.Below solution is one way of work around to achieve this scenario -Create a method in sessionBean for adding emp records and expose this method in DataControl.     For Ex: Here in the below code 'em" is a EntityManager.            private EntityManager em - will be member variable in sessionEJBBeanpublic void addEmpRecord(String ename, String job, BigDecimal deptno) { Emp emp = new Emp(); emp.setEname(ename); emp.setJob(job); //setting the deptno explicitly Dept dept = new Dept(); dept.setDeptno(deptno); //passing the dept object emp.setDept(dept); //persist the emp object data to Emp table em.persist(emp); }From DataControl palette Drop addEmpRecord as Method ADF button, In Edit action binding window enter the parameter values which are binded in backing bean.     For Ex:     If the name deptno textfield is binded with "deptno" variable in backing bean, then El Expression Builder pass value as "#{backingbean.deptno.value}"Binding:

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  • Mutating Programming Language?

    - by MattiasK
    For fun I was thinking about how one could build a programming language that differs from OOP and came up with this concept. I don't have a strong foundation in computer science so it might be common place without me knowing it (more likely it's just a stupid idea :) I apologize in advance for this somewhat rambling question :) Anyways here goes: In normal OOP methods and classes are variant only upon parameters, meaning if two different classes/methods call the same method they get the same output. My, perhaps crazy idea, is that the calling method and class could be an "invisible" part of it's signature and the response could vary depending on who call's an method. Say that we have a Window object with a Break() method, now anyone (who has access) could call this method on Window with the same result. Now say that we have two different objects, Hammer and SledgeHammer. If Break need to produce different results based on these we'd pass them as parameters Break(IBluntObject bluntObject) With a mutating programming language (mpl) the operating objects on the method would be visible to the Break Method without begin explicitly defined and it could adopt itself based on them). So if SledgeHammer calls Window.Break() it would generate vastly different results than if Hammer did so. If OOP classes are black boxes then MPL are black boxes that knows who's (trying) to push it's buttons and can adapt accordingly. You could also have different permission sets on methods depending who's calling them rather than having absolute permissions like public and private. Does this have any advantage over OOP? Or perhaps I should say, would it add anything to it since you should be able to simply add this aspect to methods (just give access to a CallingMethod and CallingClass variable in context) I'm not sure, might be to hard to wrap one's head around, it would be kinda interesting to have classes that adopted themselves to who uses them though. Still it's an interesting concept, what do you think, is it viable?

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  • Question on methods in Object Oriented Programming

    - by mal
    I’m learning Java at the minute (first language), and as a project I’m looking at developing a simple puzzle game. My question relates to the methods within a class. I have my Block type class; it has its many attributes, set methods, get methods and just plain methods. There are quite a few. Then I have my main board class. At the moment it does most of the logic, positioning of sprites collision detection and then draws the sprites etc... As I am learning to program as much as I’m learning to program games I’m curious to know how much code is typically acceptable within a given method. Is there such thing as having too many methods? All my draw functionality happens in one method, should I break this into a few ‘sub’ methods? My thinking is if I find at a later stage that the for loop I’m using to cycle through the array of sprites searching for collisions in the spriteCollision() method is inefficient I code a new method and just replace the old method calls with the new one, leaving the old code intact. Is it bad practice to have a method that contains one if statement, and place the call for that method in the for loop? I’m very much in the early stages of coding/designing and I need all the help I can get! I find it a little intimidating when people are talking about throwing together a prototype in a day too! Can’t wait until I’m that good!

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