Question

与制作JFrame对象相反，我扩展了JFrame并创建了一个Panel。我希望我创建的面板在用户单击某些按钮时关闭，但是即使我使用dispose（）方法放置动作侦听器，该面板仍保持打开状态。我知道我的代码现在是一团糟，但是请您看看我做错了什么。

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;


public class StartUp extends JFrame{

    private JButton createAccount, login;
    private static final int WIDTH = 500;
    private static final int HEIGHT = 300;

    public StartUp(){

        createView();

        setTitle("MovieBase Login");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setSize(WIDTH, HEIGHT);
        setMinimumSize(new Dimension(400, 200));
        setLocationRelativeTo(null);
        setResizable(false);

    }

    private void createView(){

        JPanel panel = new JPanel(new GridBagLayout());
        getContentPane().add(panel);
        GridBagConstraints constraints = new GridBagConstraints();
        constraints.insets = new Insets(10,10,10,10);

        constraints.gridx = 0;
        constraints.gridy = 1;

        JLabel label = new JLabel("Welcome to MovieBase, your personal Movie Database!");
        panel.add(label, constraints);

        constraints.gridx = 0;
        constraints.gridy = 2;
        createAccount = new JButton("Create Account");

        panel.add(createAccount, constraints);

        createAccount.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e){
                new CreateAccount();
            }

        });


        createAccount.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e)
            {
               dispose();
            }
        });


        constraints.gridx = 0;
        constraints.gridy = 3;

        login = new JButton("Login");
        panel.add(login, constraints);

        login.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e){
                new Login();
            }

        });

        login.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e)
            {

            }
        });

    }


    public static void main(String[] args)
    {
       SwingUtilities.invokeLater(new Runnable(){
            public void run(){
                try{
                    StartUp window = new StartUp();
                    window.setVisible(true);
                }
                catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

}

单独班级

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class CreateAccount extends JFrame{

    private JLabel user, pass; //label next to username and password field
    private JTextField username; //enter username
    private JPasswordField password; //enter password
    private JButton create;
    private String u, p;
    private static final int WIDTH = 500;
    private static final int HEIGHT = 300;

    public CreateAccount(){

        createView();

        setTitle("Create Account");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setSize(WIDTH, HEIGHT);
        setMinimumSize(new Dimension(WIDTH, HEIGHT));
        setLocationRelativeTo(null);
        setResizable(false);


    }

    public void setUser(String usn){
        u = usn;
    }

    public String getUser(){
        return u;
    }

    public void setPass(String psd){
        p = psd;
    }

    public String getPass(){
        return p;
    }


    private void createView(){

        setVisible(true);
        JPanel panelMain = new JPanel(null);
        getContentPane().add(panelMain);

        user = new JLabel("Username: ");
        panelMain.add(user);
        user.setBounds(50, 30, 120, 25);

        username = new JTextField();
        panelMain.add(username);
        username.setBounds(140, 30, 150, 25);


        pass = new JLabel("Password: ");
        panelMain.add(pass);
        pass.setBounds(50, 100, 120, 25);

        password = new JPasswordField();
        panelMain.add(password);
        password.setBounds(140, 100, 150, 25);

        create = new JButton("Create");
        panelMain.add(create);
        create.setBounds(170, 180, 100,25);


        create.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {

                String usn = username.getText();
                String psd = password.getText();
                setUser(usn);
                setPass(psd);
            }


        });

        create.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e){
                new Login2().setVisible(true);
            }

        });

        create.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
               dispose();
            }
        });



    }

}

Answer 1

dispose上没有JPanel方法-我看到您两次调用它，两次都是在JFrame的扩展名上。

更具体地说-Java模式中的方法总是以object.method(arguments)的形式在某些对象上调用-Java提供了一种快捷方式表示法-如果未指定对象，则暗示this。调用dispose()时，并没有明确提供正在调用它的任何对象，并且this在上下文中是JFrame的扩展。

如果您只想隐藏面板，则可以致电setVisible(false)

即使我调用JPanel.dispose（），面板也保持打开状态

1 个答案: