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  • Problem with setVisible (true)

    - by Jessy
    The two examples shown below are same. Both are supposed to produce same result e.g. generate the coordinates of images displayed on JPanel. Example 1, works perfectly (print the coordinates of images), however example 2 returning 0 for the coordinate. I was wondering why because, I have put the setvisible (true) after adding the panel, in both examples. The only difference is that example 1 used extends JPanel and example 2 extends JFrame EXAMPLE 1: public class Grid extends JPanel{ public static void main(String[] args){ JFrame jf=new JFrame(); jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); final Grid grid = new Grid(); jf.add(grid); jf.pack(); Component[] components = grid.getComponents(); for (Component component : components) { System.out.println("Coordinate: "+ component.getBounds()); } jf.setVisible(true); } } EXAMPLE 2: public class Grid extends JFrame { public Grid () { setLayout(new GridBagLayout()); GridBagLayout m = new GridBagLayout(); Container c = getContentPane(); c.setLayout (m); GridBagConstraints con = new GridBagConstraints(); //construct the JPanel pDraw = new JPanel(); ... m.setConstraints(pDraw, con); pDraw.add (new GetCoordinate ()); // call new class to generate the coordinate c.add(pDraw); pack(); setVisible(true); } public static void main(String[] args) { new Grid(); } }

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  • Refactor throwing not null exception if using a method that has a dependency on a certain contructor

    - by N00b
    In the method below the second constructor accepts a ForumThread object which the IncrementViewCount() method uses. There is a dependency between the method and that particular constructor. Without extracting into a new private method the null check in IncrementViewCount() and LockForumThread() (plus other methods not shown) is there some simpler re-factoring I can do or the implementation of a better design practice for this method to guard against the use of the wrong constructor with these dependent methods? Thank you for any suggestions in advance. private readonly IThread _forumLogic; private readonly ForumThread _ft; public ThreadLogic(IThread forumLogic) : this(forumLogic, null) { } public ThreadLogic(IThread forumLogic, ForumThread ft) { _forumLogic = forumLogic; _ft = ft; } public void Create(ForumThread ft) { _forumLogic.SaveThread(ft); } public void IncrementViewCount() { if (_ft == null) throw new NoNullAllowedException("_ft ForumThread is null; this must be set in the constructor"); lock (_ft) { _ft.ViewCount = _ft.ViewCount + 1; _forumLogic.SaveThread(_ft); } } public void LockForumThread() { if (_ft == null) throw new NoNullAllowedException("_ft ForumThread is null; this must be set in the constructor"); _ft.ThreadLocked = true; _forumLogic.SaveThread(_ft); }

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  • Run a flash movie in flex application.

    - by Irwin
    I've a flash movie that I would like to use inside of a flex application, very similar to a preloader. Looking at this tutorial, http://www.flexer.info/2008/02/07/very-first-flex-preloader-customization/, I expected it would be a matter of not extending "Preloader" and extending "Sprite" and using the class i created wherever i needed. Alas, the movie I created, is not being shown. This is the code for my class containing the movie, made based on the tutorial above: package { import mx.preloaders.DownloadProgressBar; import flash.display.Sprite; import flash.events.ProgressEvent; import flash.events.Event; import mx.events.FlexEvent; import flash.display.MovieClip; public class PlayerAnimation extends Sprite { [Embed("Player.swf")] public var PlayerGraphic:Class; public var mc:MovieClip; public function PlayerAnimation():void { super(); mc = new PlayerGraphic(); addChild(mc); } public function Play():void { mc.gotoAndStop(2); } } }

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  • How the simples GUI countdown is supposed to work?

    - by Roman
    I am trying to write the simples GUI countdown. I found in Internet some code but it is already too fancy for me. I am trying to keep it as simple as possible. So, I just want to have a window saying "You have 10 second left". The number of second should decrease every second from 10 to 0. I wrote a code. And I think I am close to the working solution. But I still missing something. Could you pleas help me to find out what is wrong? Here is my code: import javax.swing.*; public class Countdown { static JLabel label; // Method which defines the appearance of the window. private static void showGUI() { JFrame frame = new JFrame("Simple Countdown"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JLabel label = new JLabel("Some Text"); frame.add(label); frame.pack(); frame.setVisible(true); } // Define a new thread in which the countdown is counting down. static Thread counter = new Thread() { public void run() { for (int i=10; i>0; i=i-1) { updateGUI(i,label); try {Thread.sleep(1000);} catch(InterruptedException e) {}; } } }; // A method which updates GUI (sets a new value of JLabel). private static void updateGUI(final int i, final JLabel label) { SwingUtilities.invokeLater(new Runnable(i,label) { public Runnable(int i, JLabel label) { this.i = i; this.label = label; } public void run() { label.setText("You have " + i + " seconds."); } }); } // The main method (entry point). public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { showGUI(); //counter.start(); } }); //counter.start(); } } And I have several concrete question about this code: Where should I place the counter.start();? (In my code I put it on 2 places. Which one is correct?) Why compiler complains about the constructor for Runnable? It says that I have an invalid method declaration and I need to specify the returned type. ADDED: I made the suggested corrections. And then I execute the code and get: Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at Worker.run(Worker.java:12) In the Worker.java in the line 12 I have: label.setText("You have " + i + " seconds.");.

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  • Java OO design confusion: how to handle actions modified by states modified by actions...

    - by Arvanem
    Hi folks, Given an entity, whose action is potentially modified by states (of the entity and other entities) in turn potentially modified by other actions (of the entity and other entities) , what is the best way to code or design to handle the potential existence of the modifiers? Speaking metaphorically, I am coding a Java application representing a piano. As you know a piano has keys (which, when pressed, emit sound) and pedals (which, when pressed, modify the keys' sounds). My base class structure is as follows: Entity (for keys and pedals) State (this holds each entity's states, e.g. name such as "soft pedal", and boolean "Pressed"), Action (this holds each entity's actions, e.g. play sound when pressed, or modify others sounds). By composition, the Entity class has a copy of each of State and Action inside it. e.g.: public class Entity { State entityState = new State(); Action entityAction = new Action(); Thus I have coded a "C-Sharp" key Entity. When I "press" that entity (set its "Pressed" state to true), its action plays a "C-Sharp" sound and then sets its "Pressed" state to false. At the same time, if the "C-Sharp" key entity is not "tuned", its sound deviates from "C-Sharp". Meanwhile I have coded a "soft pedal" Entity. When that entity is "pressed", no sound plays but its action is to make softer the sound of the "C-Sharp" and other key entities. I have also coded a "sustain pedal" Entity. When that entity is "pressed", no sound plays but its action is to enable reverberation of the sound of the "C-Sharp" and other key entities. Both the "soft" and "sustain pedals" can be pressed at the same time with the result that keys entities become both softened and reverberating. In short, I do not understand how to make this simultaneous series of states and actions modify each other in a sensible OO way. I am wary of coding a massive series of "if" statements or "switches". Thanks in advance for any help or links you can offer.

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  • Java Process.waitFor() and IO streams

    - by lynks
    I have the following code; String[] cmd = { "bash", "-c", "~/path/to/script.sh" }; Process p = Runtime.getRuntime().exec(cmd); PipeThread a = new PipeThread(p.getInputStream(), System.out); PipeThread b = new PipeThread(p.getErrorStream(), System.err); p.waitFor(); a.die(); b.die(); The PipeThread class is quite simple so I will include it in full; public class PipeThread implements Runnable { private BufferedInputStream in; private BufferedOutputStream out; public Thread thread; private boolean die = false; public PipeThread(InputStream i, OutputStream o) { in = new BufferedInputStream(i); out = new BufferedOutputStream(o); thread = new Thread(this); thread.start(); } public void die() { die = true; } public void run() { try { byte[] b = new byte[1024]; while(!die) { int x = in.read(b, 0, 1024); if(x > 0) out.write(b, 0, x); else die(); out.flush(); } } catch(Exception e) { e.printStackTrace(); } try { in.close(); out.close(); } catch(Exception e) { } } } My problem is this; p.waitFor() blocks endlessly, even after the subprocess has terminated. If I do not create the pair of PipeThread instances, then p.waitFor() works perfectly. What is it about the piping of io streams that is causing p.waitFor() to continue blocking? I'm confused as I thought the IO streams would be passive, unable to keep a process alive, or to make Java think the process is still alive.

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  • How to invoke a delegate with a null parameter?

    - by Rodney Burton
    I get a null exception if I try to pass a null parameter to a delegate during an invoke. Here's what the code looks like: public void RequestPhoto() { WCF.Service.BeginGetUserPhoto(Contact.UserID, new AsyncCallback(RequestPhotoCB), null); } public void RequestPhotoCB(IAsyncResult result) { var photo = WCF.Service.EndGetUserPhoto(result); UpdatePhoto(photo); } public delegate void UpdatePhotoDelegate(Binary photo); public void UpdatePhoto(Binary photo) { if (InvokeRequired) { var d = new UpdatePhotoDelegate(UpdatePhoto); Invoke(d, new object[] { photo }); } else { var ms = new MemoryStream(photo.ToArray()); var bmp = new Bitmap(ms); pbPhoto.BackgroundImage = bmp; } } The problem is with the line: Invoke(d, new object[] { photo }); If the variable "photo" is null. What is the correct way to pass a null parameter during an invoke? Thanks!

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  • How to set text above and below a JButton icon?

    - by mre
    I want to set text above and below a JButton's icon. At the moment, in order to achieve this, I override the layout manager and use three JLabel instances (i.e. 2 for text and 1 for the icon). But this seems like a dirty solution. Is there a more direct way of doing this? Note -I'm not looking for a multi-line solution, I'm looking for a multi-label solution. Although this article refers to it as a multi-line solution, it actually seems to refer to a multi-label solution. EXAMPLE import java.awt.Component; import java.awt.FlowLayout; import javax.swing.BoxLayout; import javax.swing.Icon; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.SwingUtilities; import javax.swing.UIManager; public final class JButtonDemo { public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable(){ @Override public void run() { createAndShowGUI(); } }); } private static void createAndShowGUI(){ final JFrame frame = new JFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setLayout(new FlowLayout()); frame.add(new JMultiLabelButton()); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } private static final class JMultiLabelButton extends JButton { private static final long serialVersionUID = 7650993517602360268L; public JMultiLabelButton() { super(); setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); add(new JCenterLabel("Top Label")); add(new JCenterLabel(UIManager.getIcon("OptionPane.informationIcon"))); add(new JCenterLabel("Bottom Label")); } } private static final class JCenterLabel extends JLabel { private static final long serialVersionUID = 5502066664726732298L; public JCenterLabel(final String s) { super(s); setAlignmentX(Component.CENTER_ALIGNMENT); } public JCenterLabel(final Icon i) { super(i); setAlignmentX(Component.CENTER_ALIGNMENT); } } }

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  • Using PLINQ to calculate and update values within the enclosure does not work

    - by Keith
    I recently needed to do a running total on a report. Where for each group, I order the rows and then calculate the running total based on the previous rows within the group. Aha! I thought, a perfect use case for PLINQ! However, when I wrote up the code, I got some strange behavior. The values I was modifying showed as being modified when stepping through the debugger, but when they were accessed they were always zero. Sample Code: class Item { public int PortfolioID; public int TAAccountID; public DateTime TradeDate; public decimal Shares; public decimal RunningTotal; } List<Item> itemList = new List<Item> { new Item { PortfolioID = 1, TAAccountID = 1, TradeDate = new DateTime(2010, 5, 1), Shares = 5.335m, }, new Item { PortfolioID = 1, TAAccountID = 1, TradeDate = new DateTime(2010, 5, 2), Shares = -2.335m, }, new Item { PortfolioID = 2, TAAccountID = 1, TradeDate = new DateTime(2010, 5, 1), Shares = 7.335m, }, new Item { PortfolioID = 2, TAAccountID = 1, TradeDate = new DateTime(2010, 5, 2), Shares = -3.335m, }, }; var found = (from i in itemList where i.TAAccountID == 1 select new Item { TAAccountID = i.TAAccountID, PortfolioID = i.PortfolioID, Shares = i.Shares, TradeDate = i.TradeDate, RunningTotal = 0 }); found.AsParallel().ForAll(x => { var prevItems = found.Where(i => i.PortfolioID == x.PortfolioID && i.TAAccountID == x.TAAccountID && i.TradeDate <= x.TradeDate); x.RunningTotal = prevItems.Sum(s => s.Shares); }); foreach (Item i in found) { Console.WriteLine("Running total: {0}", i.RunningTotal); } Console.ReadLine(); If I change the select for found to be .ToArray(), then it works fine and I get calculated reuslts. Any ideas what I am doing wrong?

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  • DataGridView with row-specific DataGridViewComboBoxColumn contents in C# Windows Forms 3.5

    - by XXXXX
    So I have something like the following data structure (constructors omitted) class Child { public string Name { get; set; } public int Age { get; set; } } class Parent { public string Name { get; set; } public List <Child> Children { get; private set; } // never null; list never empty public Child FavoriteChild { get; set; } // never null; always a reference to a Child in Children } List < Parent > Parents; What I want to do is show a DataGridView where each row is a Parent from Parent list. Each row should have two columns: a text box showing the parent's name and a DataGridViewComboBoxColumn containing that parent's children, from which the user can select the parent's favorite child. I suppose I could do the whole thing manually, but I'd like to do all this with more-or-less standard Data Binding. It's easy enough to bind the DataGridView to the list of parents, and easy enough to bind the selected child to the FavoriteChild property. The part that's giving me difficulty is that it looks like the Combo Box column wants to bind to one data source for all the combo-box's contents on all rows. I'd like each instance of the combo box to bind to the list of each parent's children. I'm fairly new to C#/Windows Forms, so I may well be missing something obvious. Or it could be that "you can't get there from here." It's not too tough to make a separate list of all the children and filter it by parent; I'm looking into that possibility right now. Is this feasible, or is there a better way?

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  • Magi squares, recursive

    - by user310827
    Hi, my problem is, I'm trying to permute all posibilities for 3x3 square and check if the combination is magic. I've added a tweak with (n%3==0) if statement that if the sum of numbers in row differs from 15 it breaks the creation of other two lines... but it doesn't work, any suggestions, I call the function with Permute(1). public static class Global { //int[] j = new int[6]; public static int[] a= {0,0,0,0,0,0,0,0,0}; public static int[] b= {0,0,0,0,0,0,0,0,0}; public static int count = 0; } public static void Permute(int n) { int tmp=n-1; for (int i=0;i<9;i++){ if (Global.b[i]==0 ) { Global.b[i]=1; Global.a[n-1]=i+1; if ((n % 3) == 0) { if (Global.a[0+tmp]+Global.a[1+tmp]+Global.a[2+tmp] == 15) { if (n<9) { Permute(n+1); } else { isMagic(Global.a); } } else break; } else { Permute(n+1); } Global.b[i]=0; } } }

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  • WCF Multiple Services

    - by David
    Hi, im brand spanking new to WCF and Im trying to understand how to correctly expose my BLL to it. I created my first Resource.svc and IResource.svc Resource.svc [ServiceBehavior] public class Resources : IResources { #region IResources Members public List<Model.Resource> GetAll() { return Repository.Inventory.Resource.GetAll(true); } public List<Model.Resource> GetAllEnabled() { return Repository.Inventory.Resource.GetAllEnabled(true); } #endregion } IResource.cs [ServiceContract] public interface IResources { [OperationContract] List<Model.Resource> GetAll(); [OperationContract] List<Model.Resource> GetAllEnabled(); } So this all works, My windows app can talk to the service and all is great. So I now need to access some information, I have created another .svc file called Project.svc and IProject.cs, this contains the same info as resource (apart from the type is Project) But this now means I have another webservice, surley this is not right!?

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  • java annotations - problem with calling a locator class from a Vaadin Project

    - by George
    Hello, I'm not sure how to explain this without writing several pages so I hope the actual code is more expressive. I've made a jar containing multiple annotation declaration similar to the following: @Target(ElementType.PACKAGE) @Retention(RetentionPolicy.RUNTIME) public @interface MarkedPackage { } then I have made a test jar containing several classes in several packages and marked just one package with the above annotation (with package-info.java) like below: @myPackage.MarkedPackage package package.test.jar; this jar had in its build path the jar containing the annotations. then I made a static class that has a method (LoadPlugins) that retrieves a list with all the jars of a directory. Then it searches through the jars for the 'package-info' class and checks if that classes package contains the MarkedPackage annotation. by calling this: if (checkPackageAnnotation(thisClass.getPackage())) where thisClass is the package-info class retrieved via a classloader. and: public static boolean checkPackageAnnotation(AnnotatedElement elem) { System.out.println(elem.getAnnotations().length); if (elem == null || !elem.isAnnotationPresent(MarkedPackage.class)) return false; return true; } the elem.getAnnotatios().length is there for debug purposes. And the problem appears when I call the method from the static class: if I call it from a main function: public class MyMain { public static void main(String[] args){ PluginUtils.LoadPlugins(); } } everything works perfectly it displays '1' from that System.out.println(elem.getAnnotations().length); But if I call it from a button from my Vaadin project: header.addComponent(new Button("CallThat", new Button.ClickListener() { public void buttonClick(ClickEvent event) { PluginUtils.LoadPlugins(); } })); It displays '0' from that System.out.println(elem.getAnnotations().length); Also I should mention that I created the main inside my Vaadin project so it would have the exact same build path and resources. Is there a problem with web applications and that "@Retention(RetentionPolicy.RUNTIME)" ? hope I was clear enough... Hope someone has a solution for me... If you need more information - let me know. Thank you.

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  • Executing logic before save or validation with EF Code-First Models

    - by Ryan Norbauer
    I'm still getting accustomed to EF Code First, having spent years working with the Ruby ORM, ActiveRecord. ActiveRecord used to have all sorts of callbacks like before_validation and before_save, where it was possible to modify the object before it would be sent off to the data layer. I am wondering if there is an equivalent technique in EF Code First object modeling. I know how to set object members at the time of instantiation, of course, (to set default values and so forth) but sometimes you need to intervene at different moments in the object lifecycle. To use a slightly contrived example, say I have a join table linking Authors and Plays, represented with a corresponding Authoring object: public class Authoring { public int ID { get; set; } [Required] public int Position { get; set; } [Required] public virtual Play Play { get; set; } [Required] public virtual Author Author { get; set; } } where Position represents a zero-indexed ordering of the Authors associated to a given Play. (You might have a single "South Pacific" Play with two authors: a "Rodgers" author with a Position 0 and a "Hammerstein" author with a Position 1.) Let's say I wanted to create a method that, before saving away an Authoring record, it checked to see if there were any existing authors for the Play to which it was associated. If no, it set the Position to 0. If yes, it would find set the Position of the highest value associated with that Play and increment by one. Where would I implement such logic within an EF code first model layer? And, in other cases, what if I wanted to massage data in code before it is checked for validation errors? Basically, I'm looking for an equivalent to the Rails lifecycle hooks mentioned above, or some way to fake it at least. :)

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  • Problems with listening an event in child object in Actionscript

    - by Raigomaru
    I have two classes. The first one (the starting class): package { import flash.display.Sprite; import flash.events.KeyboardEvent; import tetris.*; public class TetrisGame extends Sprite { private var _gameWell:Well; public function TetrisGame() { _gameWell = new Well(); addChild(_gameWell); } } } The second: package tetris { import flash.display.Sprite; import flash.events.KeyboardEvent; public class Well extends Sprite { public function Well() { super(); addEventListener(KeyboardEvent.KEY_DOWN, onKeyboard); } private function onKeyboard(event:KeyboardEvent):void { //some code is here } } } But when I press any buttons on my keyboard, the child class Well doesn't have any reaction. What's the problem?

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  • How do I execute a sequence of servlets?

    - by Legend
    I have some servlets that act as individual URLs for populating a database for some dummy testing. Something of the form: public class Populate_ServletName extends HttpServlet { public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException { resp.setContentType("text/plain"); //Insert records //Print confirmation } } I have about 6 such servlets which I want to execute in a sequence. I was thinking of using setLocation to set the next page to be redirected but was not sure if this is the right approach because the redirects should happen after the records have been inserted. Specifically, I am looking for something like this: public class Populate_ALL extends HttpServlet { public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException { resp.setContentType("text/plain"); //Call Populate_1 //Call Populate_2 //Call Populate_3 //... } } Any suggestions?

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  • How come this image won't resize to fit the sprite?

    - by George Edison
    I have this snippet of ActionScript code that is supposed to resize an image to fit the sprite: package { import flash.display.Sprite; import flash.display.Bitmap; import flash.events.Event; public class Main extends Sprite { [Embed(source = 'img.png')] private var TheImage:Class; public static const TheImageWidth:Number = 1300; public static const TheImageHeight:Number = 1300; public function Main():void { if (stage) init(); else addEventListener(Event.ADDED_TO_STAGE, init); } private function init(e:Event = null):void { removeEventListener(Event.ADDED_TO_STAGE, init); // entry point var image:Bitmap = new TheImage(); addChild(image); image.scaleX = width / TheImageWidth; image.scaleY = height / TheImageHeight; } } } Why isn't it working?

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  • dynamic class property $$value in php

    - by cellis
    How can i reference a class property knowing only a string? class Foo { public $bar; public function TestFoobar() { $this->foobar('bar'); } public function foobar($string) { echo $this->$$string; //doesn't work } } what is the correct way to eval the string?

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  • ListView not showing up in fragment

    - by aindurti
    When I insert a listview in a fragment in my application, it doesn't show up after I populate it with items. In fact, the application crashes due to a NullPointerException. Can anybody help me? Here is the detail activity from which I show the fragments. package com.example.sample; import android.content.Intent; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentTransaction; import android.support.v4.app.NavUtils; import android.widget.ArrayAdapter; import android.widget.ListView; import com.actionbarsherlock.app.ActionBar; import com.actionbarsherlock.app.ActionBar.Tab; import com.actionbarsherlock.app.SherlockFragmentActivity; import com.actionbarsherlock.view.MenuItem; /** * An activity representing a single Course detail screen. This activity is only * used on handset devices. On tablet-size devices, item details are presented * side-by-side with a list of items in a {@link CourseListActivity}. * <p> * This activity is mostly just a 'shell' activity containing nothing more than * a {@link CourseDetailFragment}. */ public class CourseDetailActivity extends SherlockFragmentActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_course_detail); // Show the Up button in the action bar. ActionBar actionBar = getSupportActionBar(); actionBar.setDisplayHomeAsUpEnabled(true); actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); // initiating both tabs and set text to it. ActionBar.Tab assignTab = actionBar.newTab().setText("Assignments"); ActionBar.Tab schedTab = actionBar.newTab().setText("Schedule"); ActionBar.Tab contactTab = actionBar.newTab().setText("Contact"); // Create three fragments to display content Fragment assignFragment = new Assignments(); Fragment schedFragment = new Schedule(); Fragment contactFragment = new Contact(); assignTab.setTabListener(new MyTabsListener(assignFragment)); schedTab.setTabListener(new MyTabsListener(schedFragment)); contactTab.setTabListener(new MyTabsListener(contactFragment)); actionBar.addTab(assignTab); actionBar.addTab(schedTab); actionBar.addTab(contactTab); ListView listView = (ListView) findViewById(R.id.assignlist); String[] values = new String[] { "Android", "iPhone", "WindowsMobile", "Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X", "Linux", "OS/2" }; // First paramenter - Context // Second parameter - Layout for the row // Third parameter - ID of the TextView to which the data is written // Forth - the Array of data ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, android.R.id.text1, values); // Assign adapter to ListView listView.setAdapter(adapter); } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case android.R.id.home: // This ID represents the Home or Up button. In the case of this // activity, the Up button is shown. Use NavUtils to allow users // to navigate up one level in the application structure. For // more details, see the Navigation pattern on Android Design: // // http://developer.android.com/design/patterns/navigation.html#up-vs-back // NavUtils.navigateUpTo(this, new Intent(this, CourseListActivity.class)); return true; } return super.onOptionsItemSelected(item); } class MyTabsListener implements ActionBar.TabListener { public Fragment fragment; public Fragment fragment2; public MyTabsListener(Fragment fragment) { this.fragment = fragment; } @Override public void onTabReselected(Tab tab, FragmentTransaction ft) { } @Override public void onTabSelected(Tab tab, FragmentTransaction ft) { ft.replace(R.id.main_across, fragment); } @Override public void onTabUnselected(Tab tab, FragmentTransaction ft) { ft.remove(fragment); } } } The fragment that I am currently trying to get working is called the Assignments fragment. As you can see in the CourseDetailActvity, I populate smaple items in the listview to see if it the listview shows up. The fragment gets inflated properly, but when I try to add items to the listview, the application crashes! Here is the logcat. 11-17 11:54:28.037: E/AndroidRuntime(282): FATAL EXCEPTION: main 11-17 11:54:28.037: E/AndroidRuntime(282): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.sample/com.example.sample.CourseDetailActivity}: java.lang.NullPointerException 11-17 11:54:28.037: E/AndroidRuntime(282): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663) 11-17 11:54:28.037: E/AndroidRuntime(282): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 11-17 11:54:28.037: E/AndroidRuntime(282): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 11-17 11:54:28.037: E/AndroidRuntime(282): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 11-17 11:54:28.037: E/AndroidRuntime(282): at android.os.Handler.dispatchMessage(Handler.java:99) 11-17 11:54:28.037: E/AndroidRuntime(282): at android.os.Looper.loop(Looper.java:123) 11-17 11:54:28.037: E/AndroidRuntime(282): at android.app.ActivityThread.main(ActivityThread.java:4627) 11-17 11:54:28.037: E/AndroidRuntime(282): at java.lang.reflect.Method.invokeNative(Native Method) 11-17 11:54:28.037: E/AndroidRuntime(282): at java.lang.reflect.Method.invoke(Method.java:521) 11-17 11:54:28.037: E/AndroidRuntime(282): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 11-17 11:54:28.037: E/AndroidRuntime(282): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 11-17 11:54:28.037: E/AndroidRuntime(282): at dalvik.system.NativeStart.main(Native Method) 11-17 11:54:28.037: E/AndroidRuntime(282): Caused by: java.lang.NullPointerException 11-17 11:54:28.037: E/AndroidRuntime(282): at com.example.sample.CourseDetailActivity.onCreate(CourseDetailActivity.java:66) 11-17 11:54:28.037: E/AndroidRuntime(282): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 11-17 11:54:28.037: E/AndroidRuntime(282): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 11-17 11:54:28.037: E/AndroidRuntime(282): ... 11 more

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  • How can I declare and initialize an array of pointers to a structure in C?

    - by worlds-apart89
    I have a small assignment in C. I am trying to create an array of pointers to a structure. My question is how can I initialize each pointer to NULL? Also, after I allocate memory for a member of the array, I can not assign values to the structure to which the array element points. #include <stdio.h> #include <stdlib.h> typedef struct list_node list_node_t; struct list_node { char *key; int value; list_node_t *next; }; int main() { list_node_t *ptr = (list_node_t*) malloc(sizeof(list_node_t)); ptr->key = "Hello There"; ptr->value = 1; ptr->next = NULL; // Above works fine // Below is erroneous list_node_t **array[10] = {NULL}; *array[0] = (list_node_t*) malloc(sizeof(list_node_t)); array[0]->key = "Hello world!"; //request for member ‘key’ in something not a structure or union array[0]->value = 22; //request for member ‘value’ in something not a structure or union array[0]->next = NULL; //request for member ‘next’ in something not a structure or union // Do something with the data at hand // Deallocate memory using function free return 0; }

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  • Yet another bug of JSF?

    - by Nitesh Panchal
    Hello, Again i see that the @PostConstruct is firing every time even though no binding attribute is used. See this code :- <?xml version='1.0' encoding='UTF-8' ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:ui="http://java.sun.com/jsf/facelets" xmlns:c="http://java.sun.com/jsp/jstl/core"> <h:head> <title>Facelet Title</title> </h:head> <h:body> <h:form> <c:forEach var="item" items="#{TestBean.listItems}"> <h:outputText value="#{item}"/> </c:forEach> <h:commandButton value="Click" actionListener="#{TestBean.actionListener}"/> </h:form> </h:body> </html> And this is the simplest possible bean in JSF :- package managedBeans; import java.io.Serializable; import java.util.ArrayList; import java.util.List; import javax.annotation.PostConstruct; import javax.faces.bean.ManagedBean; import javax.faces.bean.ViewScoped; @ManagedBean(name="TestBean") @ViewScoped public class TestBean implements Serializable { private List<String> listItems; public List<String> getListItems() { return listItems; } public void setListItems(List<String> listItems) { this.listItems = listItems; } public TestBean() { } @PostConstruct public void init(){ System.out.println("Post Construct fired!"); listItems = new ArrayList<String>(); listItems.add("Mango"); listItems.add("Apple"); listItems.add("Banana"); } public void actionListener(){ System.out.println("Action Listener fired!"); } } Do you see any behaviour that should cause postconstruct callback to fire each time? I think JSF 2.0 is highly unstable. If it has to fire PostConstruct each and every time what purpose does @ViewScoped serve. Why not to use @RequestScoped only? I thought i have made some mistake in my application. But when i created this simplest possible in JSF, i still get this error. Am i not understanding the scopes of JSF? or are they not testing it properly? Further, if you remove c:forEach and replace it with ui:repeat, then it works fine. Waiting for replies to confirm whether it is bug or it is intentional to stop the programmers from using jstl?

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  • Java enums in generic type

    - by Marcin Cylke
    Hi, I'd like to create a generic enum-based mapper for IBatis. I'm doing this with the below code. This does have compile time errors, which I don't know how to fix. Maybe my solution is just plain wrong (keep in mind the use of IBatis), in such case please suggest something better. Any help appreciated. What I want to achieve is to define subsequent mappers as: public class XEnumTypeHandler extends CommonEnumTypeHandler<X> { } The current code: public class CommonEnumTypeHandler<T extends Enum> implements TypeHandlerCallback { public void setParameter(ParameterSetter ps, Object o) throws SQLException { if (o.getClass().isAssignableFrom(**T**)) { ps.setString(((**T**) o).value().toUpperCase()); } else throw new SQLException("Excpected ParameterType object than: " + o); } public Object getResult(ResultGetter rs) throws SQLException { Object o = valueOf(rs.getString()); if (o == null) throw new SQLException("Unknown parameter type: " + rs.getString()); return o; } public Object valueOf(String s) { for (T pt : T.**values()**) { if (pt.**value()**.equalsIgnoreCase(s)) return pt; } return null; } } I've added error markings to the above code, the error messages are in order: T cannot be resolved The method value() is undefined for the type T The method values() is undefined for the type T The method values() is undefined for the type T

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  • ComboBox ItemTemplate does not support values of type 'Image'

    - by Charlie
    I'm trying to bind a WPF combobox to an observable collection of images. Here is my collection: public class AvatarPhoto { public int AvatarId { get; set; } public BitmapImage AvatarImage { get; set; } } public ObservableCollection<AvatarPhoto> AvailableProfilePictures { get; private set; } Here is my xaml: Visual Studio gives me this compile time error: Property 'ItemTemplate' does not support values of type 'Image'. Why is this error seen? Thanks Update: thanks for the answer! It solved the problem. Now I have updated my code but I'm seeing this in the ComboBox: Why is it not displaying pictures correctly? In the debug window I can see my collection is correctly populated:

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  • Handles Comparison: empty classes vs. undefined classes vs. void*

    - by Nawaz
    Microsoft's GDI+ defines many empty classes to be treated as handles internally. For example, (source GdiPlusGpStubs.h) //Approach 1 class GpGraphics {}; class GpBrush {}; class GpTexture : public GpBrush {}; class GpSolidFill : public GpBrush {}; class GpLineGradient : public GpBrush {}; class GpPathGradient : public GpBrush {}; class GpHatch : public GpBrush {}; class GpPen {}; class GpCustomLineCap {}; There are other two ways to define handles. They're, //Approach 2 class BOOK; //no need to define it! typedef BOOK *PBOOK; typedef PBOOK HBOOK; //handle to be used internally //Approach 3 typedef void* PVOID; typedef PVOID HBOOK; //handle to be used internally I just want to know the advantages and disadvantages of each of these approaches. One advantage with Microsoft's approach is that, they can define type-safe hierarchy of handles using empty classes, which (I think) is not possible with the other two approaches. What else? EDIT: One advantage with the second approach (i.e using incomplete classes) is that we can prevent clients from dereferencing the handles (that means, this approach appears to support encapsulation strongly, I suppose). The code would not even compile if one attempts to dereference handles. What else?

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  • Dynamic filling WrapPanel buttons from DB, setting the event handlers

    - by Anry
    I have a table: I'm using NHibernate. The class of entity: public class PurchasedItem { public virtual int Id { get; set; } public virtual Product Product { get; set; } public virtual int SortSale { get; set; } } I want to get all the records table PurchasedItems (my method returns an IList ). Records are sorted in descending order (column SortSale). How to fill WrapPanel buttons from the list IList ? For each button assign the event handler. By pressing the button display a message with the name of the product.

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