awt求助帖

libingkang 2011-01-19 10:47:58

import java.awt.Button;
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class Panel62 extends JPanel{
JFrame jframe;
Graphics2D g;
MyCanvas canvas;
Panel62(JFrame jFrame){
canvas=new MyCanvas();
canvas.setBackground(Color.WHITE);
JButton b= new JButton("开始");
JPanel p1=new JPanel();
JPanel p = new JPanel();
JTextArea tex1 = new JTextArea("被测试距离(CM)");
JTextArea tex2 = new JTextArea("实验次数");
tex1.setBounds(730, 150, 120, 30);
tex1.setFont(new Font("",Font.BOLD,14));
tex2.setBounds(777, 190, 60, 30);
tex2.setFont(new Font("",Font.BOLD,14));
JTextField t1 = new JTextField("50");
JTextField t2 = new JTextField("6");
p1.setBackground(Color.WHITE);
p1.setLayout(null);
b.setBounds(600,150,112,40);
t1.setBounds(850, 150, 60, 25);
t2.setBounds(850, 190, 60, 25);
b.setFont(new Font("黑体",Font.BOLD,25));
p1.add(tex1);
p1.add(tex2);
p1.add(t1);
p1.add(t2);
p1.add(b);
this.add(canvas);
this.setLayout(new GridLayout(2,1));
this.add(p1);
jframe = jFrame;
b.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent arg0) {
g.setColor(Color.white);
//这里怎么写

}
});
}

class MyCanvas extends JPanel {

@Override
public void paint(Graphics g) {
super.paint(g);
Graphics2D gh = (Graphics2D)g;
gh.setColor(Color.BLACK);
gh.fillOval(650, 375,6, 6);
gh.setColor(Color.RED);
gh.fillOval(800, 370, 11, 11);
gh.fillOval(950, 370, 11, 11);
gh.fillOval(1100, 370, 11, 11);
gh.fillOval(500, 370, 11, 11);
gh.fillOval(350, 370, 11, 11);
gh.fillOval(200, 370, 11, 11);
}

}
}

按钮事件里面怎么写可以按下按钮后画白色的圆把原来的覆盖掉，然后把原来的圆再每隔2秒显示一个出来

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