java - 来自另一个 JFrame 的 JTable 值

Question

我有 JTable，我想在另一帧的特定单元格中设置值。当我尝试这样做时，出现空指针异常。我更改了修饰符并删除了异常，但仍然无法设置值。

请大家帮忙

public ChequeVoucher(int id,int row){
       try {
           String str = get_bank_name(id);
           System.out.println(str); 

           table.getModel().setValueAt(str,row,5);
           table.getModel().setValueAt(id,row,4);
       } catch (SQLException f) {
       }
       setBank(id,row); 
    }

public void setBank(int id,int row){
    try {
            String str = get_bank_name(id);
            table.getModel().setValueAt(str,row,5);
        } catch (SQLException f) {
        }
    }

chequevoucher 是我的构造函数，这段代码直到现在都很好

 table.getModel().setValueAt(str,row,5);

我从中获取值的 JFrame 是

   table.addMouseListener(new MouseAdapter() {
       public void mouseClicked(MouseEvent e) {
         int row = table.getSelectedRow();
         int col = table.getSelectedColumn();
         String str_id = (String)GetID(row,0); 
         int id = Integer.parseInt(str_id);
         ChequeVoucher CV = new ChequeVoucher(id,row); 
         setVisible(false);
        }
     });

访问修饰符不是静态的，所以我得到以下错误堆栈

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at client.ChequeVoucher.(ChequeVoucher.java:215) at client.popupBanks$3.mouseClicked(popupBanks.java:130) at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:253) at java.awt.Component.processMouseEvent(Component.java:6292) at javax.swing.JComponent.processMouseEvent(JComponent.java:3267) at java.awt.Component.processEvent(Component.java:6054) at java.awt.Container.processEvent(Container.java:2041) at java.awt.Component.dispatchEventImpl(Component.java:4652) at java.awt.Container.dispatchEventImpl(Container.java:2099) at java.awt.Component.dispatchEvent(Component.java:4482) at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4577) at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4247) at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168) at java.awt.Container.dispatchEventImpl(Container.java:2085) at java.awt.Window.dispatchEventImpl(Window.java:2478) at java.awt.Component.dispatchEvent(Component.java:4482) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:644) at java.awt.EventQueue.access$000(EventQueue.java:85) at java.awt.EventQueue$1.run(EventQueue.java:603) at java.awt.EventQueue$1.run(EventQueue.java:601) at java.security.AccessController.doPrivileged(Native Method) at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87) at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98) at java.awt.EventQueue$2.run(EventQueue.java:617) at java.awt.EventQueue$2.run(EventQueue.java:615) at java.security.AccessController.doPrivileged(Native Method) at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87) at java.awt.EventQueue.dispatchEvent(EventQueue.java:614) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

When I made the modifiers static, I get no exceptions but nothing happens and I can't listen to the JTable anymore

 case KeyEvent.VK_F5:
     switch(col){
         case 4:
         //show the banks 
         popupBanks pB = new popupBanks(row); 
         pB.setVisible(true);

         break;
  }

抱歉之前不清楚的帖子

Answer 1

您调用的 ChequeVoucher 方法绝对是一个构造函数，此时，您的表为空，除非您用其他东西指定它的值。您可以在构造函数中添加表，这将解决问题。最好的解决方案是使用 JTable 作为构造函数参数创建一个 ChequeVoucher，并使用方法完成其他所有操作。