如果您不知道存在多少个密钥，请将整个集合加载到jtable中

时间：2014-12-18 04:06:11

标签： mongodb jtable mongodb-query

我不知道文件有多少把钥匙......所以我制作了一个类似的程序：

private void showresultsActionPerformed(java.awt.event.ActionEvent evt) {                                            


        Object dbs=db.getSelectedItem();
        Object colls=coll.getSelectedItem();
      String  distances=distance.getText();
      String skillss=skills.getText();


        MongoClient m = null;
        try {
            m=new MongoClient();

        } catch (UnknownHostException ex) {
            Logger.getLogger(NewJFrame.class.getName()).log(Level.SEVERE, null, ex);
        }
      DB dbv = m.getDB((String) dbs);
      DBCollection collv = dbv.getCollection((String) colls);

     DBObject doc = collv.findOne();
         Set<String> keys= doc.keySet();

        DBCursor cursor=collv.find();

     String[] columnnames=keys.toArray(new String[keys.size()]);
     DefaultTableModel tb=new DefaultTableModel(columnnames,0);
     while(cursor.hasNext()) {
              DBObject obj = cursor.next();
            int i;
              for(i=0;i<columnnames.length;i++)
              {
                  Object a = obj.get(columnnames[i]);
              tb.addColumn(columnnames[i], (Object[]) a);
              } 

     }
      main.setModel(tb);

    }

用mongo数据填充jtable ..但点击按钮后会发生以下错误：---- 

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: org.bson.types.ObjectId cannot be cast to [Ljava.lang.Object;
    at NewJFrame.showresultsActionPerformed(NewJFrame.java:217)
    at NewJFrame.access$100(NewJFrame.java:12)
    at NewJFrame$2.actionPerformed(NewJFrame.java:74)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6516)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3320)
    at java.awt.Component.processEvent(Component.java:6281)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4872)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4698)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2719)
    at java.awt.Component.dispatchEvent(Component.java:4698)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:694)
    at java.awt.EventQueue$3.run(EventQueue.java:692)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:708)
    at java.awt.EventQueue$4.run(EventQueue.java:706)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: org.bson.types.ObjectId cannot be cast to [Ljava.lang.Object;
    at NewJFrame.showresultsActionPerformed(NewJFrame.java:217)
    at NewJFrame.access$100(NewJFrame.java:12)
    at NewJFrame$2.actionPerformed(NewJFrame.java:74)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6516)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3320)
    at java.awt.Component.processEvent(Component.java:6281)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4872)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4698)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2719)
    at java.awt.Component.dispatchEvent(Component.java:4698)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:694)
    at java.awt.EventQueue$3.run(EventQueue.java:692)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:708)
    at java.awt.EventQueue$4.run(EventQueue.java:706)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
BUILD SUCCESSFUL (total time: 7 seconds)

有人能告诉我为什么我会收到此错误以及如何解决此问题？我导入了import org.bson.types.ObjectId;

1 个答案:

答案 0 :(得分：0)

Exception非常清楚地告诉你问题是什么以及它究竟在哪里 - 当你在这一行实际上是一个ObjectId时，你假设某个东西是一个Object数组：

tb.addColumn(columnnames[i], (Object[]) a);

(Object[])意味着你要投射到一个对象数组，但它不是一个对象数组，它是一个ObjectId。将该行更改为

tb.addColumn(columnnames[i], (ObjectId) a);

并且此错误将消失。

但是，我并不保证这会解决您的所有问题。实际上，我希望你会得到一个不同的错误。

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