java - 从 JFrame 获取输入

Question

我对如何编程有点困惑。我有一个使用两个文本字段扩展 JFrame 的类。我希望能够从 JFrame 获取输入。不知何故，只需等待我的 mainMaybe 类的输入...有什么想法吗？

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JTextField;


public class mainMaybe extends JFrame{
    JTextField login;
    JTextField pass;

    public mainMaybe() throws InterruptedException{
        login = new JTextField();
        pass = new JTextField();
        pass.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent arg0) {
                 System.out.println("DO SOMETHING");
            }       
        });
        add(login,BorderLayout.NORTH);
        add(pass,BorderLayout.SOUTH);
        pack();
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public void returnEmail(){
        //SOME HOW WAIT FOR THE ACTION LISTENER?
    }

    public static void main(String[] args) throws InterruptedException {
        new mainMaybe().returnEmail(); 
        //CONTROL SHOULD STAY WITH mainMaybe until an email is returned         
    }

}

Answer 1

Java Swing 基于事件驱动架构的概念。因此，事件会触发操作，并且根据这些事件，您将执行某种操作。

Using Swing Component开始理解并最终实现您想要在 UI 及其相应行为方面实现的目标将是一个很好的起点。因此，我建议您阅读一些相关内容，然后尝试解决您想要实现的目标。

我不太确定你想要实现什么，但如果我是你，我会有两个文本字段，可能附加一些标签和一个“提交”按钮。我会向此按钮添加一个 ActionListener 来执行某种操作。

也许是SSCCE可能会帮助您入门。那么看看这段代码:

package com.test;

import javax.swing.JOptionPane;

public class SimpleUI extends javax.swing.JFrame {

    /**
     * Creates new form SimpleUI
     */
    public SimpleUI() {
        initComponents();
    }

    private void initComponents() {

        mainPanel = new javax.swing.JPanel();
        labelName = new javax.swing.JLabel();
        textName = new javax.swing.JTextField();
        jLabel1 = new javax.swing.JLabel();
        textPassword = new javax.swing.JPasswordField();
        jButton1 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        mainPanel.setBorder(javax.swing.BorderFactory.createEmptyBorder(2, 2, 2, 2));

        labelName.setText("Name: ");

        jLabel1.setText("Password: ");

        jButton1.setText("Submit");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout mainPanelLayout = new javax.swing.GroupLayout(mainPanel);
        mainPanel.setLayout(mainPanelLayout);
        mainPanelLayout.setHorizontalGroup(
            mainPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(mainPanelLayout.createSequentialGroup()
                .addGroup(mainPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(labelName)
                    .addComponent(jLabel1))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(mainPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addComponent(textName)
                    .addComponent(textPassword, javax.swing.GroupLayout.DEFAULT_SIZE, 195, Short.MAX_VALUE))
                .addGap(18, 18, 18)
                .addComponent(jButton1)
                .addGap(0, 65, Short.MAX_VALUE))
        );
        mainPanelLayout.setVerticalGroup(
            mainPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(mainPanelLayout.createSequentialGroup()
                .addContainerGap()
                .addGroup(mainPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(labelName)
                    .addComponent(textName, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(mainPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1)
                    .addComponent(textPassword, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButton1))
                .addContainerGap(15, Short.MAX_VALUE))
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(mainPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(mainPanel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
        );

        pack();
    }


    /**
    *   This is the method that is called when an action is performed.
    *   Over here I just simply show an error message if any of the text fields are empty or just show their names.
    */
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
        String name         = textName.getText();
        String password     = String.valueOf(textPassword.getPassword());

        if("".equals(password) || "".equals(name)){
            JOptionPane.showMessageDialog(this, "Name or password is empty!", "Incorrect Input", JOptionPane.ERROR_MESSAGE);
        }else{
            JOptionPane.showMessageDialog(this, "Hello "+name+" with password "+password, "Incorrect Input", JOptionPane.PLAIN_MESSAGE);
        }
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {

        try {
            javax.swing.UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(SimpleUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(SimpleUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(SimpleUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(SimpleUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }


        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new SimpleUI().setVisible(true);
            }
        });
    }

    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel labelName;
    private javax.swing.JPanel mainPanel;
    private javax.swing.JTextField textName;
    private javax.swing.JPasswordField textPassword;

}

注意:我使用 NetBeans IDE 生成了此代码，因此我不必处理太多有关布局或任何内容的事情。如果您想了解布局，这里有一个有趣的教程:"A Visual Guide to Layout Managers"

我的主要想法是向您展示事件是如何触发的。所以我所做的就是在“提交”按钮中添加一个 actionlistener ，当有人单击该按钮时，我会执行某种操作。希望你能得到这张照片。