各位大神，为什么java界面无法显示？

Question

import java.awt.BorderLayout;
import java.awt.Button;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.UIManager;

public class kiujh extends JFrame{

/**
 * @param args
 */
public kiujh(String title) throws Exception{
    super(title);

    //设置基本设置
    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
    this.setSize(300, 150);
    this.setLocation(300, 200);
    this.setLayout(new BorderLayout());
    this.setVisible(true);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    //设置用户名和密码框
    JPanel jp1=new JPanel();
    JTextField jt=new JTextField("Please enter the User's name");
    JPasswordField pa=new JPasswordField("Please enter the Password");
    jp1.setLayout(new BorderLayout());
    jp1.add(jt, BorderLayout.NORTH);
    jp1.add(pa, BorderLayout.SOUTH);

    //设置登录按钮
    JPanel jp2=new JPanel();
    Button bt1=new Button("登录");
    Button bt2=new Button("退出");
    jp2.setLayout(new BorderLayout());
    jp2.add(bt1, BorderLayout.WEST);
    jp2.add(bt2, BorderLayout.EAST);

    //设置标题
    JLabel jl=new JLabel("登录界面");

    //添加到界面里
    this.add(jl, BorderLayout.NORTH);
    this.add(jp1, BorderLayout.CENTER);
    this.add(jp2,BorderLayout.SOUTH);

}
public static void main(String[] args) throws Exception {
    // TODO Auto-generated method stub
    kiujh j=new kiujh("登录");
}

}

Answer 1

运行一下，看看控制台的输出内容，分析一下错误好了，或者panel不设置布局试一下