为什么我不能将JPanel添加到JFrame？

这是代码：

import javax.swing.SwingUtilities; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JLabel; import java.awt.event.*; import java.awt.*; public class GameWindow { private String[] players; private JFrame frame; // Constructor. public GameWindow(String[] players) { this.players = players; } // Start the window in the EDT. public void start() { SwingUtilities.invokeLater(new Runnable() { public void run() { showWindow(); controller.start(); } }); } // Defines the general properties of and starts the window. public void showWindow() { frame = new JFrame("Game"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(600,400); frame.setVisible(true); } // The thread controlling changes of panels in the main window. private Thread controller = new Thread() { public void run() { frame.add(generatePartnerSelectionPanel()); frame.invalidate(); frame.validate(); } }; // Generate the panel for the selection of a partner. private JPanel generatePartnerSelectionPanel() { JPanel panel = new JPanel(); panel.add(new JLabel("Pleas select a partner:")); return panel; } } 

我应该看到“请选择合作伙伴”而我不这样做。 为什么？

我想这是因为我没有看到Thread的run方法中的帧。

添加：

可能是我需要在事件发送线程中进行所有更新……我现在就检查它。

增加2：

我试图修改控制器的代码。 它没有帮助：

  private Thread controller = new Thread() { public void run() { SwingUtilities.invokeLater(new Runnable() { public void run() { frame.getContentPane().add(generatePartnerSelectionPanel()); frame.invalidate(); frame.validate(); } }); } }; 

增加3：

好。 这是代码的完整版本（不起作用）：

 import javax.swing.SwingUtilities; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JLabel; import java.awt.event.*; import java.awt.*; public class GameWindow { private String[] players; private JFrame frame; // Constructor. public GameWindow(String[] players) { this.players = players; } // Start the window in the EDT. public void start() { SwingUtilities.invokeLater(new Runnable() { public void run() { showWindow(); controller.start(); } }); } // Defines the general properties of and starts the window. public void showWindow() { frame = new JFrame("Game"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(600,400); frame.setVisible(true); } // The thread controlling changes of panels in the main window. private Thread controller = new Thread() { public void run() { SwingUtilities.invokeLater(new Runnable() { public void run() { frame.getContentPane().add(generatePartnerSelectionPanel()); frame.invalidate(); frame.validate(); } }); } }; // Generate the panel for the selection of a partner. private JPanel generatePartnerSelectionPanel() { JPanel panel = new JPanel(); panel.add(new JLabel("Pleas select a partner:")); return panel; } } 

增加4：

以下代码也不起作用。 顺便说一下，为什么我要从一start删除invokeLater ？ 我确实需要在事件派发线程中启动GUI，并且invokelater 。

 import javax.swing.SwingUtilities; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JLabel; import java.awt.event.*; import java.awt.*; public class GameWindow { private String[] players; private JFrame frame; // Constructor. public GameWindow(String[] players) { this.players = players; } // Start the window in the EDT. public void start() { // SwingUtilities.invokeLater(new Runnable() { // public void run() { showWindow(); controller.start(); // } // }); } // Defines the general properties of and starts the window. public void showWindow() { frame = new JFrame("Game"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(600,400); frame.setVisible(true); } // The thread controlling changes of panels in the main window. private Thread controller = new Thread() { public void run() { SwingUtilities.invokeLater(new Runnable() { public void run() { frame.getContentPane().add(generatePartnerSelectionPanel()); frame.invalidate(); frame.validate(); } }); } }; // Generate the panel for the selection of a partner. private JPanel generatePartnerSelectionPanel() { JPanel panel = new JPanel(); panel.add(new JLabel("Pleas select a partner:")); return panel; } } 

增加5：

我解决了这个问题。

1. 在课堂上我有start和showWindow方法。 从主程序我调用了错误的方法（ showWindow而不是start ）。 所以，我替换了start方法（以避免与线程的开始混淆），然后我从主类调用startWindow ，它解决了问题。

Answer 1

您正在从 invokeLater调用创建更新线程。 这不是你使用invokeLater 。 invokeLater用于从单独的线程更新UI组件。 调用invokeLater ， 从单独的线程传递更新UI组件的Runnable 。

有关其他信息，请参阅JavaDocs

例如：

 // Start the window in the EDT. public void start() { showWindow(); controller.start(); } // Defines the general properties of and starts the window. public void showWindow() { frame = new JFrame("Game"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(600,400); frame.setVisible(true); } // The thread controlling changes of panels in the main window. private Thread controller = new Thread() { public void run() { // some long running process, I assume, but at // some point you want to update UI: SwingUtilities.invokeLater(new Runnable() { public void run() { frame.add(generatePartnerSelectionPanel()); frame.invalidate(); frame.validate(); } }); } };