e1103.java

java小程序

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class E1103 extends JFrame implements ActionListener
{
private Timer t;
private int color=0;
private Color[] colors={Color.red,Color.green,Color.blue};

public E1103()
{
super("E1103:动态改变直线颜色");
t=new Timer(500,this);
t.start();
setSize(400,200);
addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)//定义关闭窗口方法 
{
t.stop();
System.exit(0);
}
});
setVisible(true);
}

public void actionPerformed(ActionEvent e)//响应各种事件
{
color++;
if(color>2) color=0;
Graphics g=getGraphics();
g.setColor(colors[color]);
g.drawLine(10,100,390,100);
g.drawLine(10,104,390,104);
g.drawLine(10,108,390,108);
g.dispose();
}

public void paint(Graphics g)
{
g.setFont(new Font("Serif",Font.BOLD,20));
g.drawString("按顺序变换水平线的红绿蓝色",60,60);
g.setColor(colors[0]);
g.drawLine(10,100,390,100);
g.drawLine(10,104,390,104);
g.drawLine(10,108,390,108);
}

public static void main(String args[])
{
E1103 app=new E1103();
}
}