chapter7.java

java的书本上的一个小程序,是java的一个简单应用例子

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
public class chapter7 extends Applet implements AdjustmentListener
{
	Scrollbar mySlider=new Scrollbar(Scrollbar.HORIZONTAL,0,1,0,400);
	int radius=0;
	int x=200,y=200;
	public void init()
	{
		mySlider.setUnitIncrement(1);
		mySlider.setBlockIncrement(10);
		setLayout(new BorderLayout());
		add("North",mySlider);
		mySlider.addAdjustmentListener(this);
    }
    public void paint(Graphics g)
    {
    	g.drawOval(x-radius,y-radius,radius*2,radius*2);
    }
    public void adjustmentValueChanged(AdjustmentEvent ae)
    {
    	if(ae.getAdjustable()==mySlider)
    	{
    		radius=ae.getValue()/2;
    		repaint();
    	}
    }	
}