Java - Screen turns black, when setting a JFrame to Fullscreen

问题

I'm trying to draw something on a Canvas, add it to a JFrame and then set this JFrame to Fullscreen. My problem is: in fullscreenmode I only see a black screen. Before the screen turns black I shortly can see the pink background of the canvas.

Drawing directly on a JFrame and then setting it to fullscreen works perfectly fine and I can see the testtext. I assume there is a problem with displaying the Canvas properly.

Here is my code:

public class FullscreenTest extends Canvas {

    private JFrame mainFrame;

    public FullscreenTest(){
        this.mainFrame = new JFrame();
        JPanel contentPane = (JPanel) mainFrame.getContentPane();
        contentPane.add(this);
    }

    public void run(DisplayMode dm){
        setBackground(Color.PINK);
        setForeground(Color.WHITE);
        setFont(new Font("Arial", Font.PLAIN, 24));

        Screen s = new Screen();

        s.setFullScreen(dm, this.mainFrame);

        try {
            Thread.sleep(5000);
        } catch (InterruptedException exc) { exc.printStackTrace(); }

        s.closeFullScreenWindow();
    }

    public void paint(Graphics g){      
        g.drawString("This is some testtext", 200, 200);
    }

    public static void main(String[] args){
        DisplayMode dm = new DisplayMode(800, 600, 32, DisplayMode.REFRESH_RATE_UNKNOWN);
        FullscreenTest test = new FullscreenTest();
        test.run(dm);
    }
}

Here is what the Screen.setFullScreen(DisplayMode dm, JFrame window) method does:

//graphicsDevice = GraphicsEnvironment.getLocalGraphicsEnvironment()
//                 .getDefaultScreenDevice();
public void setFullScreen(DisplayMode dm, JFrame window){
    window.setUndecorated(true);
    window.setResizable(false);
    graphicsDevice.setFullScreenWindow(window);

    if(dm != null && graphicsDevice.isDisplayChangeSupported()){
        graphicsDevice.setDisplayMode(dm);          
    }
}

Does anyone have a clue why I don't see the JFrame's content in fullscreen?

回答1:

1) you have three general issues

never block EDT by using Thread.sleep(5000); use Swing Timer instead, demonstrations here
(if aren't there really important reasons) don't mixing AWT with Swing the rest is here, and use JPanel instead of Canvas (for Canvas is there paint method, for JPanel is there paintComponent)
your public void paint(Graphics g){ is to the JFrame instead of Canvas and locked by Thread.sleep(5000);

2) Swing GUI rellated should be wrapped into invokeLater() meaning

public static void main(String[] args){

回答2:

I agree with mKorbel (actually, I have your code working with corrections he suggest). Just one hint to achieve more predictable results further: take control on colors in paint() method. Default color for background may vary on different systems. On my system it draws white text on light-red background. But if it will draw black text on black background, test will look like "not working".

回答3:

hey i had he same problem and the screen turns black every time i run the program. in the part of the paint method , you wrote, which i think that it is from Bucky tutorial which is amazing by the way :

public void paint(Graphics g){      
        g.drawString("This is some testtext", 200, 200);
    }

all you have to do is to use "super"

public void paint(Graphics g){
        super.paint(g);
        g.drawString("This is some testtext", 200, 200);
    }

I tried it myself and it is working just fine.

来源：https://stackoverflow.com/questions/9649394/java-screen-turns-black-when-setting-a-jframe-to-fullscreen

标签

java

swing

jframe

awt

fullscreen