rubber.java

java练习程序

///
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class Rubber extends Applet implements ActionListener, MouseMotionListener
{
	int x=-1, y=-1, 橡皮擦通知=0, 清除通知=0;
	Color c=new Color(255, 0, 0);int con=3;
	Button b_red, b_blue, b_green, 清除, b_quit;
	public void init()
	{
		addMouseMotionListener(this);
		b_red=new Button("画红色图形");
		b_blue=new Button("蓝色图形");
		b_green=new Button("绿色图形");
		b_quit=new Button("橡皮");
		清除=new Button("清除");
		add(b_red); add(b_green); add(b_blue); add(b_quit);add(清除);
		b_red.addActionListener(this); b_green.addActionListener(this);
		b_blue.addActionListener(this); b_quit.addActionListener(this);
		清除.addActionListener(this);
	}
	
	public void paint(Graphics g)
	{
		if(x!=-1&&y!=-1&&清除通知==0&&橡皮擦通知==0)
		{
			g.setColor(c);
			g.fillOval(x, y, con, con);
		}
		else if(橡皮擦通知==1&&清除通知==0)
		{
			g.clearRect(x, y, 10, 10);
		}
		else if(橡皮擦通知==0&&清除通知==1)
		{
			g.clearRect(0, 0, getSize().width, getSize().height);
		}
	}
	
	public void mouseDragged(MouseEvent e)
	{
		x=(int)e.getX();y=(int)e.getY();
		repaint();
	}
	
	public void mouseMoved(MouseEvent e)
	{ }
	
	public void update(Graphics g)
	{
		paint(g);
	}
	
	public void actionPerformed(ActionEvent e)
	{
		if(e.getSource()==b_red)
		{
			橡皮擦通知=0;清除通知=0; c=new Color(255, 0, 0);
		}
		else if(e.getSource()==b_green)
		{
			橡皮擦通知= 0; 清除通知= 0;  c=new Color(0, 255, 0);
		}
		else if(e.getSource()==b_blue)
		{
			橡皮擦通知= 0;
			清除通知= 0;
			c=new Color(0, 0, 255);
		}
		if(e.getSource()==b_quit)
		{
			橡皮擦通知=1;清除通知=0;
		}
		if(e.getSource()==清除 )
		{
			橡皮擦通知=1; 清除通知=0; 
			repaint();
		}
	}
}