为什么这里的repaint方法无效？

[knightzhuwei]

import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class F {
	public static void main(String[] args) {
		ButtonFrame frame = new ButtonFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setVisible(true);
	}
}
class ButtonFrame extends JFrame {
	JButton b= new JButton();
	FillPanel p = new FillPanel();
	public ButtonFrame() {
		this.setSize(200,200);
		this.add(b,BorderLayout.NORTH);
		b.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				//p.repaint();这句无效
				ButtonFrame.this.repaint();//貌似这句也无效
			}
		});	
	}
}
class FillPanel extends JPanel {
	private int i;
	protected void paintComponent(Graphics g) {
		//super.paintComponent(g);
			 System.out.println("paint");
			g.drawString(i+"", 100, 100);
			i++;
		} 
	}

求问这是为什么啊

[__浮夸]

等待高手...

[Dreamsea_2008]

我只是在Jtree中用过这个函数，还挺有效的

[knightzhuwei]

....
我明白了 没有add。。。
是我脑残了。。悲剧...

[imasmallbird]

[Quote=引用楼主 knightzhuwei 的帖子:]
Java code
import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class F {
public static void main(String[] args) {
ButtonFrame frame = new ButtonFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_C…
[/Quote]

你光加了按钮也没加this.add(p);呀
把p加上，然后把p.repain()注释去掉试一下