java工具类之Graphics

package huaxian;

import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Graphics;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class huaxian2 extends JFrame {

    private JPanel jp;
    private JFrame jf;
    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        huaxian2 h2 = new huaxian2();
    }
    
    public huaxian2(){
        
        this.setSize(500, 500);
        this.setVisible(true);
        this.setDefaultCloseOperation(jf.EXIT_ON_CLOSE);
        
        jp = new JPanel();
        this.add(jp);
        
    }
    
    @Override
    public void paint(Graphics g){
        super.paint(g);
        g.drawLine(50, 350, 498, 350);
        g.drawLine(50, 50, 50, 350);
    }
}