ballpanel.java

自己写的弹球程序～～比较适合初学者去看～～

package day03.ball;

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.util.ArrayList;

import javax.swing.JPanel;

/**
 * 显示小球的面板
 * @author Administrator
 *
 */
public class BallPanel extends JPanel{
	private double f;//面板表面摩擦力
	//用一个ArrayList来保存所有的小球
	private ArrayList balls ;
	
	public BallPanel(double f){
		this.f=f;
		balls=new ArrayList();
	}
	
	public BallPanel(){
		this(0.002);
	}
	   
	public void addBall(Ball b){
		balls.add(b);
	}

	/**
	 * 重写父类的paintComponent方法，绘出所有小球。
	 */
	public void paintComponent(Graphics g){
		super.paintComponent(g);
		Graphics2D g2 = (Graphics2D)g;
		for (int i = 0; i < balls.size(); i++){
			Ball b = (Ball)balls.get(i);
			b.draw(g2);
		}     
	}

	public double getF() {
		return f;
	}
}