e1616.java

java小程序

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import javax.swing.*;
public class E1616 extends JApplet implements ItemListener
{
private JRadioButton redButton,greenButton;
private ButtonGroup group;
private Color lineColor;
private int startX,startY,endX,endY;
private MyListener myListener;
public void init()
{
setLayout(new FlowLayout()); 
redButton=new JRadioButton("红色",true);
greenButton=new JRadioButton("绿色",false);
redButton.addItemListener(this);
greenButton.addItemListener(this);
group=new ButtonGroup();
group.add(redButton);
group.add(greenButton);
add(redButton);
add(greenButton);
myListener=new MyListener();
addMouseListener(myListener);
lineColor=Color.red;
}


public void itemStateChanged(ItemEvent e)
{
if(e.getSource()==redButton)
lineColor=Color.red;
else if(e.getSource()==greenButton)
lineColor=Color.green;
}

class MyListener extends MouseAdapter
{
public void mousePressed(MouseEvent e)
{
startX=e.getX();
startY=e.getY();
}
public void mouseReleased(MouseEvent e)
{
endX=e.getX();
endY=e.getY();
repaint();
}
}
public void paint(Graphics g)
{
g.setColor(lineColor);
g.drawLine(startX,startY,endX,endY);
}
}