ch7_e7_19.java

来自「各种关于JAVA的初级编程」· Java 代码 · 共 35 行

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

public class ch7_e7_19 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();
        }
    }
    
}