Jbutton將消失在彈出菜單中顯示

Question

我加聽衆對我Jbutton將在彈出菜單，但彈出菜單出現時，這些Jbutton消失，我需要我的懸停的按鈕光標，使他們再次出現後。這是爲什麼？

（這裏所有的方法都是在同一個班）

public Inventory() { 
    setLayout(null); 
    setBounds(0, 0, 175, 210); 

    initPopupMenu(); // this just sets what is inside the popup menu 
    int x; 
      // 30 buttons 
    for(x = 0; x < 30; x++) { 
     button[x] = new JButton(); 
     add(button[x]); 
     button[x].addMouseListener(this); 
    } 

    x = 0; 
      // it's a grid of buttons 
    for(int i = 0; i < 5; i++) 
     for(int j = 0; j < 6; j++) { 
      button[x].setBounds(i*35+1,j*35+1, 33,33); 
      x++; 
     } 


} 

public void mouseClicked(MouseEvent e) { 
    for(int j = 0; j < 30; j++) // i tried this one but it still disappears 
     button[j].repaint(); 

    for(int i = 0; i < 30; i++) { 
     if(e.getSource() == button[i]) { 
      System.out.println("You pressed Button "+i); 
      popup.show(e.getComponent(), e.getX(), e.getY()); 
     } 

    } 

} 

這是什麼情況，使用

Answer 1

停止null佈局，似乎可以是關於這個問題的一個。你JFrame似乎有點BLACK對我來說，這是一些THEME或新LOOK AND FEEL您使用的，可以是這東西的原因了。這裏檢查了這一點，它的工作完美無缺這裏與此代碼：

import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 

public class ButtonPopUp 
{ 
    private static final int SIZE = 30; 
    private JButton[] button = new JButton[SIZE]; 
    private JPopupMenu popup = new JPopupMenu("Hello World"); 

    private void createAndDisplayGUI() 
    { 
     JFrame frame = new JFrame("Button POP UP Example"); 
     frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); 
     frame.setLocationByPlatform(true); 

     final JPanel contentPane = new JPanel(); 
     contentPane.setLayout(new GridLayout(0, 5)); 

     JMenuItem menuItem1 = new JMenuItem("Menu Item 1"); 
     JMenuItem menuItem2 = new JMenuItem("Menu Item 2"); 
     //popup.add(greetings); 
     popup.insert(menuItem1, 0); 
     popup.insert(menuItem2, 1); 

     for (int i = 0; i < SIZE; i++) 
     { 
      button[i] = new JButton(); 
      button[i].setBorder(BorderFactory.createEtchedBorder()); 
      button[i].addMouseListener(new MouseAdapter() 
      { 
       public void mouseClicked(MouseEvent me) 
       { 
        System.out.println("I am WORKING!!"); 
        popup.show((JComponent)me.getSource(), me.getX(), me.getY()); 
       } 
      }); 
      contentPane.add(button[i]); 
     } 

     frame.getContentPane().add(contentPane); 
     frame.setSize(175, 250); 
     frame.setVisible(true); 
    } 

    public static void main(String... args) 
    { 
     SwingUtilities.invokeLater(new Runnable() 
     { 
      public void run() 
      { 
       new ButtonPopUp().createAndDisplayGUI(); 
      } 
     }); 
    } 
} 

這裏是輸出：