changecolor.java

非常好的JAVA学习资料

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class changeColor extends Applet implements ActionListener{
    Label label1 = new Label();
    Button b1=new Button("red");
    Button b2=new Button("blue");
    Color newcolor;

    public void init(){
	this.setBackground(Color.lightGray);
	this.setForeground(Color.black);
	label1.setText("please select colour:");
	this.setLayout(new FlowLayout());
	this.add(label1);
	this.add(b1);
	this.add(b2);
	b1.addActionListener(this);
	b2.addActionListener(this);
        newcolor=Color.green;
	//repaint();
    }
    public void actionPerformed(ActionEvent e){
	  if(e.getSource()==b1){
		  newcolor=new Color(255,0,0);
		  repaint();
	  }
	  if(e.getSource()==b2){
  		  newcolor=new Color(0,0,255);
		  repaint();
	  }
	}

     public void paint(Graphics g){
	g.setColor(newcolor);
	g.fillOval(100,30,30,30);
    }
}