Java：在swing窗口等待用户输入

所以，我在大约一周前开始学习java，我遇到了一些问题，我正在建立一个小程序来训练使用swing和oop / java。

该程序（到目前为止）有一个MainClass和一个Window类。 MainClass创建Window类的实例，该实例创建JFrame并将用户输入保存在字段中。

此时，MainClass打印输出，我通过getters方法获得输出。

问题是我仍然以程序的方式思考：MainClass打印null，因为它不等待窗口的istance来获取用户输入。

如何修复它，从而在打印之前主要等待窗口接受用户输入？

铌。 Jframe的东西工作，窗口出现，只是MainClass不等待它做它应该做的事情。 我可以（我认为？）使用一些睡眠命令等待，但它似乎完全错误。

这是MainClass.java的代码

import java.util.Arrays; public class MainClass { private char[] password; private String pin; public static void main(String[] args) { Window w = new Window(); System.out.println(w.getPin() + Arrays.toString(w.getPassword()) + '1'); } } 

和Window.java

 import java.awt.*; import javax.swing.*; import java.awt.Window.Type; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.Arrays; import net.miginfocom.swing.MigLayout; public class Window extends JFrame{ private JTextField textField_1; private JButton btnNewButton; private JPanel panel; private JPasswordField passwordField; private char[] password = new char[10]; private String pin; public Window() { this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setLocationRelativeTo(null); this.setSize(370, 150); this.setForeground(new Color(192, 192, 192)); this.setTitle("Access Password Manager"); this.setResizable(false); panel = new JPanel(); getContentPane().add(panel, BorderLayout.CENTER); panel.setLayout(new MigLayout("", "[70.00][132.00,grow][44.00][67.00,grow][61.00][]", "[19.00][34.00][]")); JLabel lblNewLabel = new JLabel("Password"); panel.add(lblNewLabel, "cell 0 1,alignx trailing,aligny center"); passwordField = new JPasswordField(); passwordField.setColumns(13); panel.add(passwordField, "cell 1 1,alignx center"); JLabel lblNewLabel_1 = new JLabel("Key"); panel.add(lblNewLabel_1, "cell 2 1,alignx center,aligny center"); textField_1 = new JTextField(); panel.add(textField_1, "cell 3 1,alignx left,aligny center"); textField_1.setColumns(4); btnNewButton = new JButton("Log In"); ListenForButton listener = new ListenForButton(); btnNewButton.addActionListener(listener); panel.add(btnNewButton, "cell 4 1"); this.setVisible(true); } private class ListenForButton implements ActionListener{ @Override public void actionPerformed(ActionEvent e) { if(e.getSource() == btnNewButton){ if (passwordField.getPassword().length < 10){ password = passwordField.getPassword().clone(); } pin = textField_1.getText(); } } } public char[] getPassword(){ return password; } public String getPin(){ return pin; } } 

编辑：

这不仅仅是关于打印，我知道我可以直接进入Window.class。 如果我解释不好，我很抱歉。 请将println视为“一旦窗口将它们保存为输入，我需要访问并处理这些字段”。

Answer 1

您可以使用modal dialog来获取用户输入，该对话框将阻止代码在可见时执行，并在它变为不可见时继续执行（这很神奇）， 请查看如何创建对话框以获取更多详细信息

更新

modal dialog只会阻止事件调度线程（技术上它不会阻止它，它只是绕过它），请参阅初始线程了解更多详细信息

 import java.awt.BorderLayout; import java.awt.Color; import java.awt.EventQueue; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.Arrays; import javax.swing.JButton; import javax.swing.JDialog; 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; import net.miginfocom.swing.MigLayout; public class MainClass { private char[] password; private String pin; public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } System.out.println("Before Window"); Window w = new Window(); System.out.println("After Window"); System.out.println(w.getPin() + Arrays.toString(w.getPassword()) + '1'); } }); } public static class Window extends JDialog { private JTextField textField_1; private JButton btnNewButton; private JPanel panel; private JPasswordField passwordField; private char[] password = new char[10]; private String pin; public Window() { this.setModal(true); this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); this.setLocationRelativeTo(null); this.setSize(370, 150); this.setForeground(new Color(192, 192, 192)); this.setTitle("Access Password Manager"); this.setResizable(false); panel = new JPanel(); getContentPane().add(panel, BorderLayout.CENTER); panel.setLayout(new MigLayout("", "[70.00][132.00,grow][44.00][67.00,grow][61.00][]", "[19.00][34.00][]")); JLabel lblNewLabel = new JLabel("Password"); panel.add(lblNewLabel, "cell 0 1,alignx trailing,aligny center"); passwordField = new JPasswordField(); passwordField.setColumns(13); panel.add(passwordField, "cell 1 1,alignx center"); JLabel lblNewLabel_1 = new JLabel("Key"); panel.add(lblNewLabel_1, "cell 2 1,alignx center,aligny center"); textField_1 = new JTextField(); panel.add(textField_1, "cell 3 1,alignx left,aligny center"); textField_1.setColumns(4); btnNewButton = new JButton("Log In"); ListenForButton listener = new ListenForButton(); btnNewButton.addActionListener(listener); panel.add(btnNewButton, "cell 4 1"); this.setVisible(true); } private class ListenForButton implements ActionListener { @Override public void actionPerformed(ActionEvent e) { if (e.getSource() == btnNewButton) { if (passwordField.getPassword().length < 10) { password = passwordField.getPassword().clone(); } pin = textField_1.getText(); } } } public char[] getPassword() { return password; } public String getPin() { return pin; } } } 

Answer 2

如果您希望在按钮单击时打印结果，则可以在按钮的动作侦听器中打印它。 如果您希望在用户输入任何内容后立即打印，您可以在密码文本字段中添加动作侦听器。

窗口/视图

 public class Window extends JFrame{ private Controller controller; private Model model; public Window(Controller controller, Model model) { this.controller = controller; this.model = model; } 

模型

 public class Model { private String password; //getters and setters } 

调节器

 public class Controller { public void doSomething() { // do anything. Views could invoke controller methods to do things and is usually invoked when certain events happen. } 

主要

 public class Main { public static void main(String[] args) { new Window(new Controller(), new Model()); } 

Answer 3

你应该使用事件。 如果按下窗口中的按钮，您的主类可以监听事件。 例如

 public static void main(String[] args) { Window w = new Window(); w.getBtnNewButton().addActionListener(new ActionListener(){ @Override public void actionPerformed(ActionEvent e) { System.out.println(w.getPin() + Arrays.toString(w.getPassword()) + '1'); } }); } 

在这种情况下，您必须为按钮创建一个公共getter，因此您可以从主类访问它。