setVisible（true/false）錯誤JFrame

-2

所以，我有一個問題。我知道問題是什麼，但我不知道如何解決。我會給你的代碼。setVisible（true/false）錯誤JFrame

public void initialize2(){ 

    txtWaaropGokken = new JTextField(); 
    txtWaaropGokken.setFont(new Font("Tahoma", Font.BOLD, 13)); 
    txtWaaropGokken.setHorizontalAlignment(SwingConstants.CENTER); 
    txtWaaropGokken.setText("Waar wil je op gokken?"); 
    txtWaaropGokken.setBounds(10, 11, 414, 32); 
    frame.getContentPane().add(txtWaaropGokken); 
    txtWaaropGokken.setColumns(10); 
    txtWaaropGokken.setEditable(false); 

    JButton ChansesSimples = new JButton("Chanses Simples"); 
    ChansesSimples.setBounds(50, 65, 155, 32); 
    frame.getContentPane().add(ChansesSimples); 
    ChansesSimples.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent arg0) { 



      Random getal = new Random(); 
      int nummer; 

      nummer=getal.nextInt(37); 

      txtHetBalletjeRolt = new JTextField(); 
      txtHetBalletjeRolt.setFont(new Font("Tahoma", Font.BOLD, 13)); 
      txtHetBalletjeRolt.setHorizontalAlignment(SwingConstants.CENTER); 
      txtHetBalletjeRolt.setText("Het balletje is nu aan het rollen."); 
      txtHetBalletjeRolt.setBounds(10, 11, 414, 32); 
      frame.getContentPane().add(txtHetBalletjeRolt); 
      txtHetBalletjeRolt.setColumns(10); 
      txtHetBalletjeRolt.setEditable(false); 

      ChansesSimples.setVisible(false); 
      Douzaines.setVisible(false); \\HERE I DO GET THE ERROR 
      Colonne.setVisible(false); \\HERE I DO GET THE ERROR 
      TransversaleSimple.setVisible(false); \\HERE I DO GET THE ERROR 
      Carre.setVisible(false); \\HERE I DO GET THE ERROR 
      TransversalePlein.setVisible(false); \\HERE I DO GET THE ERROR 
      Cheval.setVisible(false); \\HERE I DO GET THE ERROR 
      Plein.setVisible(false); \\HERE I DO GET THE ERROR 
      Cheval.setVisible(false); \\HERE I DO GET THE ERROR 






      if(nummer == 1 || nummer == 3 || nummer == 5 || nummer == 7 || nummer == 9 || nummer == 12 || nummer == 14 || nummer == 16 || nummer == 18 || nummer == 19 || nummer == 21 || nummer == 23 || nummer == 25 || nummer == 27 || nummer == 30 || nummer == 32 || nummer == 34 || nummer == 36){  

       txtRoodGewonnen = new JTextField(); 
       txtRoodGewonnen.setFont(new Font("Tahoma", Font.BOLD, 13)); 
       txtRoodGewonnen.setHorizontalAlignment(SwingConstants.CENTER); 
       txtRoodGewonnen.setText("Gefeliciteerd! " + nummer + " is een rood nummer. Je hebt gewonnen!"); 
       txtRoodGewonnen.setBounds(10, 11, 414, 32); 
       frame.getContentPane().add(txtRoodGewonnen); 
       txtRoodGewonnen.setColumns(10); 
       txtRoodGewonnen.setEditable(false); 

       bedrag = bedrag + inzet * 1; 

      } 
      else{ 

       txtRoodVerloren = new JTextField(); 
       txtRoodVerloren.setFont(new Font("Tahoma", Font.BOLD, 13)); 
       txtRoodVerloren.setHorizontalAlignment(SwingConstants.CENTER); 
       txtRoodVerloren.setText(nummer + " is geen rood nummer. Je hebt verloren."); 
       txtRoodVerloren.setBounds(10, 11, 414, 32); 
       frame.getContentPane().add(txtRoodVerloren); 
       txtRoodVerloren.setColumns(10); 
       txtRoodVerloren.setEditable(false); 

       bedrag = bedrag - inzet; 


      } 
      txtBedrag = new JTextField(); 
      txtBedrag.setFont(new Font("Tahoma", Font.BOLD, 13)); 
      txtBedrag.setHorizontalAlignment(SwingConstants.CENTER); 
      txtBedrag.setText("Je hebt nu " + bedrag + " euro."); 
      txtBedrag.setBounds(10, 50, 414, 32); 
      frame.getContentPane().add(txtBedrag); 
      txtBedrag.setColumns(10); 
      txtBedrag.setEditable(false);   
     } 
    }); 

    JButton Douzaines = new JButton("Douzaines"); 
    Douzaines.setBounds(50, 105, 155, 32); 
    frame.getContentPane().add(Douzaines); 
    Douzaines.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent arg0) { 


     } 
    }); 

    JButton Colonne = new JButton("Colonne"); 
    Colonne.setBounds(50, 145, 155, 32); 
    frame.getContentPane().add(Colonne); 
    Colonne.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent arg0) { 


     } 
    }); 

    JButton TransversaleSimple = new JButton("Transversale Simple"); 
    TransversaleSimple.setBounds(50, 185, 155, 32); 
    frame.getContentPane().add(TransversaleSimple); 
    TransversaleSimple.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent arg0) { 


     } 
    }); 

    JButton Carre = new JButton("Carré"); 
    Carre.setBounds(240, 65, 155, 32); 
    frame.getContentPane().add(Carre); 
    Carre.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent arg0) { 


     } 
    }); 

    JButton TransversalePlein = new JButton("Transversale Plein"); 
    TransversalePlein.setBounds(240, 105, 155, 32); 
    frame.getContentPane().add(TransversalePlein); 
    TransversalePlein.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent arg0) { 


     } 
    }); 

    JButton Cheval = new JButton("Cheval"); 
    Cheval.setBounds(240, 145, 155, 32); 
    frame.getContentPane().add(Cheval); 
    Cheval.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent arg0) { 


     } 
    }); 

    JButton Plein = new JButton("Plein"); 
    Plein.setBounds(240, 185, 155, 32); 
    frame.getContentPane().add(Plein); 
    Plein.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent arg0) { 

      ChansesSimples.setVisible(false); \\HERE I DONT GET AN ERROR 
      Douzaines.setVisible(false);  \\HERE I DONT GET AN ERROR 
      Colonne.setVisible(false);  \\HERE I DONT GET AN ERROR 
      TransversaleSimple.setVisible(false); \\HERE I DONT GET AN ERROR 
      Carre.setVisible(false);  \\HERE I DONT GET AN ERROR 
      TransversalePlein.setVisible(false); \\HERE I DONT GET AN ERROR 
      Cheval.setVisible(false);  \\HERE I DONT GET AN ERROR 
      Plein.setVisible(false);  \\HERE I DONT GET AN ERROR 
      Cheval.setVisible(false);  \\HERE I DONT GET AN ERROR 


     } 
    }); 

}

問題是，如果程序''通過'JButton，如果我然後setVisible（false）。有用。正如你可以在Plein JButton中看到的，我沒有得到任何與該代碼的錯誤。但在Chanses Simples JButton中，我只能讓按鈕本身消失，如果我不想得到任何錯誤。當然，我希望玩家可以選擇第一個按鈕。有任何想法嗎？

這是錯誤代碼我得到：

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException 
    at Frame1$3.actionPerformed(Frame1.java:182) 
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source) 
    at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source) 
    at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source) 
    at javax.swing.DefaultButtonModel.setPressed(Unknown Source) 
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source) 
    at java.awt.Component.processMouseEvent(Unknown Source) 
    at javax.swing.JComponent.processMouseEvent(Unknown Source) 
    at java.awt.Component.processEvent(Unknown Source) 
    at java.awt.Container.processEvent(Unknown Source) 
    at java.awt.Component.dispatchEventImpl(Unknown Source) 
    at java.awt.Container.dispatchEventImpl(Unknown Source) 
    at java.awt.Component.dispatchEvent(Unknown Source) 
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source) 
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source) 
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source) 
    at java.awt.Container.dispatchEventImpl(Unknown Source) 
    at java.awt.Window.dispatchEventImpl(Unknown Source) 
    at java.awt.Component.dispatchEvent(Unknown Source) 
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source) 
    at java.awt.EventQueue.access$500(Unknown Source) 
    at java.awt.EventQueue$3.run(Unknown Source) 
    at java.awt.EventQueue$3.run(Unknown Source) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) 
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) 
    at java.awt.EventQueue$4.run(Unknown Source) 
    at java.awt.EventQueue$4.run(Unknown Source) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) 
    at java.awt.EventQueue.dispatchEvent(Unknown Source) 
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source) 
    at java.awt.EventDispatchThread.run(Unknown Source)

來源

2015-05-01 Raymond Timmermans

你啓動JFrame？ –

通過發佈長代碼，您限制了願意幫助您的人數。考慮簡化您的示例併發布[SSCCE]（http://sscce.org/） – Pshemo

解決此類錯誤的方法很簡單：您可以閱讀堆棧跟蹤，注意該異常是從Frame1的第182行拋出的NullPointerException異常。 java，因此去那條線問問自己在那條線上可能是空的。使用調試器可以提供幫助。然後，你要麼修復代碼，以確保什麼是空的不是，因爲它不應該，或者你通過添加一個'if'測試來檢查它是否爲null，然後訪問它的一個成員。我們不知道在代碼的貼牆上有什麼第182行，所以我們不打擾猜測。 –

在您共享的代碼，按鈕Douzaines（以及其他相關的按鈕）在聲明前被使用：

Douzaines.setVisible(false); // HERE I DO GET THE ERROR 

// [...] 

JButton Douzaines = new JButton("Douzaines"); 

// [...] 

Douzaines.setVisible(false);  // HERE I DONT GET AN ERROR

來源

2015-05-01 15:30:05

非常感謝！ –

setVisible（true/false）錯誤JFrame

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