java_AWT之移動的小球。

先放上源代碼。

package test;

import java.awt.Color;

import java.awt.Graphics;

import java.awt.Graphics2D;

import javax.swing.JFrame;

import javax.swing.JPanel;

public class Game extends JPanel{

private int posx = 0;

private int posy = 0;

public void paint(Graphics
g){

super.paint(g);

Graphics2D g2d = (Graphics2D)
g;

g2d.setColor(Color.RED);

g2d.fillOval(posx, posy, 50 ,
50);

posx += 1;

posy += 1;

}

public static void main(String[]
args) throws InterruptedException{

JFrame jframe = new JFrame();

jframe.setTitle("test");

Game game = new Game();

jframe.add(game);

jframe.setSize(300,300);

jframe.setVisible(true);

jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

while(true){

game.repaint();

Thread.sleep(10);

}

}

}

然後設斷點，進行調試。

paint(Graphics g)是由AWT線程自動運行的。可以看到右邊有Thread[AWT-EventQueue-0]這個線程。

第一個斷點super.paint(g);用戶重新刷新graphics。

第二個斷點game.repaint()是用來告訴AWT線程再次執行paint();