想问大佬们我的哪里有问题，点击之后为什么不能实现跳转？

Question

java

package PPS;

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.SwingConstants;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Toolkit;

import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.ImageIcon;

public class loginFrame extends JFrame implements ActionListener {

    private JPanel contentPane;
    private JTextField textField;
    private JTextField textField_1;
    private JButton denglu;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    loginFrame frame = new loginFrame();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }
    /**
     * Create the frame.
     */
    public loginFrame() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(0, 0, 0, 0));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        JLabel label = new JLabel("\u7528\u6237\u767B\u5F55\u754C\u9762");
        label.setBounds(5, 5, 422, 24);
        label.setFont(new Font("微软雅黑", Font.PLAIN, 18));
        label.setHorizontalAlignment(SwingConstants.CENTER);
        contentPane.add(label);

        JLabel label_1 = new JLabel("\u7528\u6237\u540D");
        label_1.setBounds(124, 79, 72, 18);
        contentPane.add(label_1);

        textField = new JTextField();
        textField.setBounds(211, 76, 86, 24);
        contentPane.add(textField);
        textField.setColumns(10);

        JLabel label_2 = new JLabel("\u5BC6\u7801");
        label_2.setBounds(125, 124, 72, 18);
        contentPane.add(label_2);

        textField_1 = new JTextField();
        textField_1.setBounds(211, 121, 86, 24);
        contentPane.add(textField_1);
        textField_1.setColumns(10);

        JButton denglu = new JButton("登录");
        this.add(denglu);
        denglu.addActionListener(this);
        setVisible(true);

        denglu.setBounds(104, 194, 113, 27);
        contentPane.add(denglu);

        JButton btnNewButton_1 = new JButton("\u53D6\u6D88");
        btnNewButton_1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
            }
        });
        btnNewButton_1.setBounds(231, 194, 113, 27);
        contentPane.add(btnNewButton_1);

        JLabel label_3 = new JLabel("");
        label_3.setBounds(27, 94, 48, 48);
        contentPane.add(label_3);
        label_3.setIcon(new ImageIcon("E:\\eclipse\\eclipse\\PPS\\resource\\customer.gif"));
    }
    public void actionPerformed(ActionEvent e) {
        if(e.getSource()==denglu) {
            this.dispose();
            new MDIFrame();
        }
    }
}