从JFrame获取输入

Question

对于如何编程，我有点困惑。我有一个类扩展JFrame与两个文本框。我希望能够从JFrame获得输入。不知何故，只是等待我的mainMaybe类的输入...任何想法？

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event-driven architecture的概念。因此，事件触发行为并基于这些事件执行某种操作。

Using Swing Component将是一个很好的点开始理解，并因此实现你想实现你的UI和它的相应行为。所以我建议你稍微阅读一下，然后尝试解决你想要达到的目标。

我不太确定你想要达到的目标，但如果我是你，我会有两个文本字段，也许有一些标签附加到它和一个“提交”按钮。我会添加一个ActionListener到这个按钮来执行某种操作。

也许SSCCE可能会帮助您开始。所以，看看下面的代码：

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：我生成使用NetBeans IDE的代码，所以我没有处理很多关于布局或任何东西。如果您想了解布局，这里是一个有趣的教程："A Visual Guide to Layout Managers"

主要的想法对我来说是向您展示事件是如何引发的。所以我做的是我在我的“提交”按钮中添加了一个actionlistener，当有人点击按钮时，我执行某种操作。希望你得到的照片。

Answer 2

我认为你的设计方法错了。在Java GUI（以及大多数类似的技术）中，您不会说“等待电子邮件地址”，而是说“当您收到电子邮件地址时告诉我”。

您在将文本框添加侦听程序的过程中会遇到一些问题 - 基本上，您希望侦听程序在texbox中的值发生更改时“触发”。听众的实现会做一些事情 - 例如，将电子邮件地址写入CONSOL然后退出。

Answer 3

替代方法，使用模态对话框（或更确切地说，其中两个）。

import javax.swing.*; 

public class LoginPrompt { 

    public static void main(String[] args) { 
     SwingUtilities.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       String username = JOptionPane.showInputDialog(null, "User Name"); 
       System.out.println("Username: " + username); 

       JPasswordField passwordField = new JPasswordField(8); 
       // a bit quirky, we need to tab to the field 
       JOptionPane.showMessageDialog(null, passwordField, "Password", 
         JOptionPane.QUESTION_MESSAGE); 
       char[] password = null; 
       password = passwordField.getPassword(); 
       System.out.println("Password: " + String.valueOf(password)); 
      } 
     }); 
    } 
}