为什么我的画布不工作？

Question

我正在创建游戏画布，但出于某种原因，我无法使其正常工作。我得到一个InvalidStateException，我没有得到什么导致它的线索。任何人都可以点亮一下吗？

我的主入口点......

public class GameTemplate { 

    public static void main(String[] args) { 
     new GameFrame(); 
    } 

} 

我JFrame的子类...

import java.awt.Dimension; 

import javax.swing.JFrame; 

public class GameFrame extends JFrame { 


    public static final short WIDTH = 1024; 
    public static final short HEIGHT = WIDTH/16 * 9; 
    public static final Dimension size = new Dimension(WIDTH, HEIGHT); 

    public GameFrame() { 
     super("Game Frame"); 
     this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     this.setSize(size); 
     this.setLocationRelativeTo(null); 
     this.setResizable(false); 
     GameCanvas canvas = new GameCanvas(size); 
     this.add(canvas); 
     canvas.start(); 
     this.setVisible(true); 
    } 

} 

我的画布子......

import java.awt.Canvas; 
import java.awt.Color; 
import java.awt.Dimension; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.RenderingHints; 
import java.awt.image.BufferStrategy; 

public class GameCanvas extends Canvas implements Runnable { 

    private boolean isRunning = false; 
    private Thread thread = null; 

    private BufferStrategy bs = null; 
    private Graphics g; 
    private Graphics2D g2d; 

    public GameCanvas(Dimension size) { 
     this.setSize(size); 
     this.setVisible(true); 
    } 

    public synchronized void start() { 
     isRunning = true; 
     thread = new Thread(this); 
     thread.start(); 
    } 

    public synchronized void stop() { 
     isRunning = false; 
     try { 
      thread.join(); 
     } catch (InterruptedException e) { 
      e.printStackTrace(); 
     } 
    } 

    @Override 
    public void run() { 
     while (isRunning) { 
      update(); 
      draw(); 
      render(); 
      try { 
       Thread.sleep(10); 
      } catch (InterruptedException e) { 
       e.printStackTrace(); 
      } 
     } 
    } 

    private void update() { 

    } 

    private void render() { 
     bs = this.getBufferStrategy(); 
     if (bs == null) { 
      this.createBufferStrategy(3); 
      return; 
     } 
     bs.show(); 
    } 

    private void draw() { 
     if (bs != null) { 
      g = bs.getDrawGraphics(); 
      g2d = (Graphics2D) g; 
      g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
        RenderingHints.VALUE_ANTIALIAS_ON); 
      g.setColor(Color.BLACK); 
      g.drawRect(0, 0, WIDTH, HEIGHT); 
     } 
    } 

} 

错误...

Exception in thread "Thread-1" java.lang.IllegalStateException: Component must have a valid peer 
at java.awt.Component$FlipBufferStrategy.createBuffers(Unknown Source) 
at java.awt.Component$FlipBufferStrategy.<init>(Unknown Source) 
at java.awt.Component$FlipSubRegionBufferStrategy.<init>(Unknown Source) 
at java.awt.Component.createBufferStrategy(Unknown Source) 
at java.awt.Canvas.createBufferStrategy(Unknown Source) 
at java.awt.Component.createBufferStrategy(Unknown Source) 
at java.awt.Canvas.createBufferStrategy(Unknown Source) 
at GameCanvas.render(GameCanvas.java:63) 
at GameCanvas.run(GameCanvas.java:47) 
at java.lang.Thread.run(Unknown Source) 

Answer 1

在框架初始化，你的情况：

public GameCanvas(Dimension size) {...} 

您需要调用方法 “frame.addNotify（）”，例如：

public GameCanvas(Dimension size) { 
    this.setSize(size); 
    this.setVisible(true); 
    this.addNotify(); 
} 

再后来了你的代码，你想包括代码：

@Override 
public void addNotify() { 
    super.addNotify(); 
} 

这只是通知帧，你希望这个类使用缓冲区。你在做什么是试图让帧使用缓冲区来创建一个图形类型缓冲策略，当帧不知道哪个组件的缓冲区用于请求的任务。

Answer 2

java.lang.IllegalStateException: Component must have a valid peer 

这可能是因为您打电话时createBufferStrategy()组件必须已隐藏。

UPDATE：

至于建议的@Andrew，你是在默认BufferStrategy.As我们可以看到混合light and heavy weight components.Rely，Canvas是不显示的，直到你把它添加到Frame。