Display.setParent() problem

[byyyk]

Hi, i'm new into LWJGL and i try to run my first app in a JFrame. I looked at some of other problems with this method but haven't found anything similiar. I add the canvas to JFrame and set is as parent (Display.setParent(canvas)) and it crashes at creating the display. This is the error:

org.lwjgl.LWJGLException: Parent.isDisplayable() must be true
        at org.lwjgl.opengl.Display.createWindow(Display.java:303)
        at org.lwjgl.opengl.Display.create(Display.java:816)
        at org.lwjgl.opengl.Display.create(Display.java:744)
        at org.lwjgl.opengl.Display.create(Display.java:725)
        at szachy.Game.init(Main.java:235)
        at szachy.Game.start(Main.java:211)
        at szachy.Game.<init>(Main.java:189)
        at szachy.MainFrame.<init>(Main.java:68)
        at szachy.Main.main(Main.java:25)

Don't know how to make it displayable, here's the code, hope you guys can help:

class Game {
    public Game(JFrame parent) {
        canvas = new Canvas();
        canvas.setSize(parent.getWidth(), parent.getHeight());
        canvas.setFocusable(true);
        canvas.setIgnoreRepaint(true);
        //System.out.println(canvas.isDisplayable()); returns false
        parent.add(canvas);
        start();
    }
  /** Game title */
  public static final String GAME_TITLE = "My Game";
 
  /** Desired frame time */
  private static final int FRAMERATE = 60;
 
  /** Exit the game */
  private static boolean finished;
 
  /** Angle of rotating square */
  private static float angle;
 
  /**
   * Application init
   * @param args Commandline args
   */
  public void start() {
    boolean fullscreen = false;
 
    try {
      init(fullscreen);
      run();
    } catch (Exception e) {
      e.printStackTrace(System.err);
      Sys.alert(GAME_TITLE, "An error occured and the game will exit.");
    } finally {
      cleanup();
    }
    System.exit(0);
  }
 
  /**
   * Initialise the game
   * @throws Exception if init fails
   */
  private static void init(boolean fullscreen) throws Exception {
    // Create a fullscreen window with 1:1 orthographic 2D projection (default)
    Display.setTitle(GAME_TITLE);
    //Display.setFullscreen(fullscreen);
    Display.setParent(canvas); //++++++++++++++++++++++++++++++++++++++++++++++++++++++++this is the problem
    // Enable vsync if we can (due to how OpenGL works, it cannot be guarenteed to always work)
    Display.setVSyncEnabled(true);
    // Create default display of 640x480
    Display.create(); //++++++++++++++++++++++++++++++++++++++++++++++++++++++++crushes here
  }
 
  /**
   * Runs the game (the "main loop")
   */
  private static void run() {
 
    while (!finished) {
      // Always call Window.update(), all the time - it does some behind the
      // scenes work, and also displays the rendered output
      Display.update();
 
      // Check for close requests
      if (Display.isCloseRequested()) {
	finished = true;
      } 
 
      // The window is in the foreground, so we should play the game
      else if (Display.isActive()) {
        logic();
        render();
        Display.sync(FRAMERATE);
      } 
 
      // The window is not in the foreground, so we can allow other stuff to run and
      // infrequently update
      else {
        try {
          Thread.sleep(100);
        } catch (InterruptedException e) {
        }
        logic();
 
	// Only bother rendering if the window is visible or dirty
        if (Display.isVisible() || Display.isDirty()) {
          render();
        }
      }
    }
  }
 
  /**
   * Do any game-specific cleanup
   */
  private static void cleanup() {
    // Close the window
    Display.destroy();
  }
 
  /**
   * Do all calculations, handle input, etc.
   */
  private static void logic() {
    // Example input handler: we'll check for the ESC key and finish the game instantly when it's pressed
    if (Keyboard.isKeyDown(Keyboard.KEY_ESCAPE)) {
      finished = true;
    }
 
    // Rotate the square
    angle += 2.0f % 360;
  }
    private static void render() {
    // clear the screen
    GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_STENCIL_BUFFER_BIT);
 
    // center square according to screen size
    GL11.glPushMatrix();
    GL11.glTranslatef(Display.getDisplayMode().getWidth() / 2, Display.getDisplayMode().getHeight() / 2, 0.0f);
 
      // rotate square according to angle
      GL11.glRotatef(angle, 0, 0, 1.0f);
      GL11.glBegin(GL11.GL_QUADS);
        GL11.glVertex2i(-50, -50);
        GL11.glVertex2i(50, -50);
        GL11.glVertex2i(50, 50);
        GL11.glVertex2i(-50, 50);
      GL11.glEnd();
 
    GL11.glPopMatrix();
  }
  static private Canvas canvas;
}

This code is a slightly changed wiki example: http://gpwiki.org/index.php/OpenGL:Tutorials:Java:LWJGL:Introduction
The other thing is if i don't set the parent it works. But it goes to fullscreen even if i set it to false and i don't see anything happen but the black screen and cursor.

[princec]

By default JFrames aren't actually visible when constructed. You need to call setVisible(true) on them first.

Cas

[byyyk]

It worked! But i'm a bit suprised cause i did set it visible but in the main method. After adding the same line to the Game constructor it stared to work. Thank you very much I can finally go on with the project
Also if anyone could refer to my second problem... I'm going to read through nehe tutorials now anyway so maybe i'll find the glitch on my own but i would be glad if someone would point that one for me so that i can see anything in 3d

EDIT: Okay, I don't know why won't this work... I tried some of the examples from nehe both on linux and windows, and every time i get only black screen. Anyone knows what might be the cause? At first i thought that maybe it is rendering the objects (because it is entering the render() method) but the color is the same as the background so I also tried examples with coloring and i still get the same, doesn't matter if i run it in JFrame or like in the tutorials. I'd appreciate any help, thanks.