在另一个类中添加Component时,JPanel不会更新

Question

我是Java Swing的新手,我遇到了一些问题.

1. 作为一个附带问题,在制作相当大的Java Swing应用程序时,分割代码的最佳方法是什么？在我的情况下,我希望有一个应用程序,其布局与Microsoft Word一样,其中有一个JToolBar,其中包含按钮和一个主JPanel,其中根据工具栏中按下的按钮进行更改.

2. 因此,如下面的代码所示,我有一个JFrame,我调用MainPanel类来创建一个面板并添加一个带按钮的ToolBar.按下按钮时,它会向面板添加一个按钮.在您调整窗口大小之前单击按钮时没有显示问题(在我的情况下,我只需手动拖动屏幕使其变大).

   public class Main {
   
   private static void createAndShowGUI() {
       //Create and set up the window.
       JFrame frame = new JFrame("MathMaker");
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   
       //Create the menu bar.  Make it have a green background.
       //MainToolBar mainTB = new MainToolBar();
       MainPanel mainPanel = new MainPanel();
   
       frame.getContentPane().add(mainPanel.getGUI(), BorderLayout.CENTER);
       frame.pack();
       frame.setVisible(true);
   }
   
   public static void main(String[] args) {
       //Schedule a job for the event-dispatching thread:
       //creating and showing this application's GUI.
       javax.swing.SwingUtilities.invokeLater(new Runnable() {
           public void run() {
               createAndShowGUI();
           }
       });
   }
   
   }
   

   public class MainPanel implements ActionListener{
   JPanel mPanel;
   JToolBar mToolBar;
   JButton addQuestion;
       public MainPanel() {
           mPanel = new JPanel(new BorderLayout());
           mToolBar = new JToolBar();
           addQuestion = new JButton("test");
   
   
       addQuestion.addActionListener(this);
   
       mPanel.setLayout(new BorderLayout());
       mPanel.setBackground(new Color(248, 213, 131));
       mPanel.setPreferredSize(new Dimension(200, 180));
   
       mToolBar.add(addQuestion);
       mPanel.add(mToolBar, BorderLayout.PAGE_START);
   }
   public JComponent getGUI()
   {
       return mPanel;
   }
   
   @Override
   public void actionPerformed(ActionEvent e) {
        JButton temp = new JButton("temp");
        mPanel.add(temp);
   }
   

   }

Answer 1

您应该重新验证您的面板

@Override
public void actionPerformed(ActionEvent e) {
   JButton temp = new JButton("temp");
   mPanel.add(temp);
   mPanel.revalidate();
   mPanel.repaint();
}