java - 如何将 JTextField 从 JFrame 传递到另一个 JFrame

Question

当我在JFrame1的JTextField中输入名字、姓氏等信息时然后点击下一步按钮，输入的数据将显示最后一个JFrame上所有输入的数据。
示例:这是动画gif，最后一帧是我想要的，因为我仍然不知道如何制作它:

我该怎么做？如果这是一个新手问题，我很抱歉，但我正在学习..

我正在使用 NetBeans GUI 构建器。

编辑:如果我做得正确的话，我会像这样创建 idk...

public class User {
    private String username;
    private String password;
    public User() {
        username = null;
        password = null;
    }

    public User getUser() {
        User user = new User();
        username = TexUsername.getText();
        return user;
    }
}

在我的 DisplayFrame 中，我不知道里面放了什么

public void setUser(User user) {
    // idk what to put here... maybe the jLabel? please help
}

问题的新更新

我的StudentRegistrationForm_1.java上的按钮

private void jButton_NextActionPerformed(java.awt.event.ActionEvent evt) {                                             
    try {
        User user = new User(TexUsername.getText(),Password.getPassword());
        StudentRegistrationForm_3 form = new StudentRegistrationForm_3(user);
        form.setUser(user);
        this.dispose();
    } catch(Exception e){JOptionPane.showMessageDialog(null, e);}
    /*
    new StudentRegistrationForm_2().setVisible(true);
    this.dispose();*/

} 

和类(class)

public class User {

    private String name;
    private char[] password;

    public User(String name, char[] password) {
        this.name = name;
        this.password = password;
    }

    public String getName() {
        return name;
    }

    public char[] getPassword() {
        return password;
    }
}

public User getUser() {
    User user = new User(TexUsername.getText(), Password.getPassword());
    return user;
}

而StudentRegistrationForm_3我添加了这样的构造函数和方法

StudentRegistrationForm_3(User user) {
    name.setText(user.getName());
}
public void setUser(User user) {
    name.setText(user.getName());
}  

我不知道为什么仍然给我 null...即使我输入了用户名和密码的值..

Answer 1

将信息从应用程序的一部分传递到另一个应用程序将取决于程序的结构。

在基本层面上，我建议将第一个屏幕中的值包装到某种自定义对象中。让我们使用User .

User将存储 accountName 的属性和password如private实例字段，可以通过 getter 访问。

基本上，你会在第一个屏幕上有某种 getter 来生成 User对象并将其传递回调用者。

第二个屏幕要么采用 User对象作为构造函数的参数或作为 setter。

大概，您会传递 User对象从编辑器 Pane 到 View Pane actionPerformed你的方法JButton

例如...

public class NewAccountPane extends JPanel {
    /*...*/
    public User getUser() {
        User user = new User();
        /* Take the values from the fields and apply them to the User Object */
        return user;
    }
}

public class AccountDetailsPane extends JPanel {
    /*...*/
    public void setUser(User user) {
        /* Take the values from the User object
         * and apply them to the UI components
         */
    }
}

在你的 actionPerformed 中方法...

public void actionPerformed(ActionEvent evt) {
    User user = instanceOfNewAccountPane.getUser();
    instanceOfAccountDetailPane.setUser(user);
    // Switch to instanceOfAccountDetailPane
}

根据问题更新进行了更新

你的用户对象几乎是正确的，但我会去掉 getUser方法。 User对象不应该有 UI 的概念，也不应该需要直接与之交互...

所以而不是...

public class User {
    private String username;
    private String password;
    public User() {
        username = null;
        password = null;
    }

    public User getUser() {
        User user = new User();
        username = TexUsername.getText();
        return user;
    }
}

我会做一些类似的事情

public class User {
    private String username;
    private char[] password;
    public User(String username, char[] password) {
        this.username = username;
        this.password = password;
    }

    public String getUserName() {
        return username;
    }

    public char[] getPassword() {
        return password;
    }
}

所以当您调用 getUser 时来自您的NewAccountPane ，您将构建 User基于表单上字段值的对象。

基本工作示例

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Passon {

    public static void main(String[] args) {
        new Passon();
    }

    private JPanel basePane;
    private EditorPane editorPane;
    private DisplayPane displayPane;

    public Passon() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                basePane = new JPanel(new CardLayout());
                basePane.add((editorPane = new EditorPane()), "Editor");
                basePane.add((displayPane = new DisplayPane()), "Display");
                ((CardLayout)basePane.getLayout()).show(basePane, "Editor");
                frame.add(basePane);

                JPanel buttons = new JPanel();
                JButton next = new JButton("Next >");
                buttons.add(next);
                frame.add(buttons, BorderLayout.SOUTH);

                next.addActionListener(new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        CardLayout layout = (CardLayout) basePane.getLayout();
                        displayPane.setUser(editorPane.getUser());
                        layout.show(basePane, "Display");
                        ((JButton)e.getSource()).setEnabled(false);
                    }
                });

                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class User {

        private String name;
        private char[] password;

        public User(String name, char[] password) {
            this.name = name;
            this.password = password;
        }

        public String getName() {
            return name;
        }

        public char[] getPassword() {
            return password;
        }

    }

    public class EditorPane extends JPanel {

        private JTextField name;
        private JPasswordField password;

        public EditorPane() {
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridx = 0;
            gbc.gridy = 0;
            add(new JLabel("User: "), gbc);
            gbc.gridy++;
            add(new JLabel("Password: "), gbc);

            gbc.gridy = 0;
            gbc.gridx++;

            name = new JTextField(20);
            password = new JPasswordField(20);

            add(name, gbc);
            gbc.gridy++;
            add(password, gbc);        
        }

        public User getUser() {
            User user = new User(name.getText(), password.getPassword());
            return user;
        }

    }

    public class DisplayPane extends JPanel {

        private JLabel name;

        public DisplayPane() {
            name = new JLabel();
            setLayout(new GridBagLayout());
            add(name);
        }

        public void setUser(User user) {
            name.setText(user.getName());
        }            
    }
}

更新更多内容

传递值是编程的基本原则。

在您的代码中，我可以看到您有两个选择..

在 jButton_NextActionPerformed您的StudentRegistrationForm_1同学们，你们现在正在做这个...

private void jButton_NextActionPerformed(java.awt.event.ActionEvent evt) {                                             
    new StudentRegistrationForm_3().setVisible(true);
    // How is StudentRegistrationForm_3 suppose to reference the User object??
    User user = new User(TexUsername.getText(),Password.getPassword());
    this.dispose();
}                                            

但是 StudentRegistrationForm_3 没有办法访问User您创建的对象。

在 jButton_NextActionPerformed您的StudentRegistrationForm_1类，您可以通过 User对象 StudentRegistrationForm_3 实例的构造函数你创建的

private void jButton_NextActionPerformed(java.awt.event.ActionEvent evt) {                                             
    User user = new User(TexUsername.getText(),Password.getPassword());
    new StudentRegistrationForm_3(user).setVisible(true);
    this.dispose();
}                                            

或者修改StudentRegistrationForm_3有一个接受 User 的方法对象

private void jButton_NextActionPerformed(java.awt.event.ActionEvent evt) {                                             
    User user = new User(TexUsername.getText(),Password.getPassword());
    StudentRegistrationForm_3 form = new StudentRegistrationForm_3(user);
    form.setUser(user);
    this.dispose();
}                                            

无论哪种方式，您都需要修改 StudentRegistrationForm_3类来支持这一点。