Question

我在调试应用程序时遇到ClassCastException。

obj = (CommonFeedBean) ResponseHandler_Review.vectorLocation1.elementAt(i);

我在上面的行中收到了ClassCastException。完整代码如下：

   for(int i=0;i<ResponseHandler_Review.vectorLocation1.size();i++)
    {       
        System.out.println("inside the for loop");
obj = (CommonFeedBean)  ResponseHandler_Review.vectorLocation1.elementAt(i);
        System.out.println("inside the obj++++++");
        hr1 = new HorizontalFieldManager(){
            protected void onFocus(int direction) {
                invalidate();
                super.onFocus(direction);
            }

        protected void onUnfocus() {
                invalidate();
                super.onUnfocus();
            }

            public void paint(Graphics graphics) {
                if (isFocus()) {
                    graphics.setBackgroundColor(Color.WHITE);
                    graphics.clear();
                }
            super.paint(graphics);
            }
        };

        String arg[] ;

             System.out.println("vectorlocation size " +     ResponseHandler_Review.vectorLocation1.size());
        arg = new String[ResponseHandler_Review.vectorLocation1.size()];
        System.out.println("after arg++++++++++");
        bit = new Bitmap[ResponseHandler_Review.vectorLocation1.size()];
        scaleBit = new Bitmap[ResponseHandler_Review.vectorLocation1.size()];
        System.out.println("after bit array+++++++");
        for(int j = 0; j< ResponseHandler_Review.vectorLocation1.size(); j++){
         arg[j] = String.valueOf(ResponseHandler_Review.vectorLocation1.elementAt(j));
         System.out.println("Vector element is "+j+" = "+arg[j]);
         bit[j] = response.getImage(arg[j]);

        scaleBit[j] = new Bitmap(162, 120);
        bit[j].scaleInto(scaleBit[j], Bitmap.FILTER_LANCZOS);
        hr1.add(new BitmapField(scaleBit[j]));
        }

        try{
        label[i] = new LabelField(obj.getTitle(), Field.FIELD_VCENTER|Field.FOCUSABLE)
        {
            public int getPreferredWidth() 
            {
                return Display.getWidth()-150;
            }
            protected boolean navigationClick(int status, int time) {
                fieldChangeNotify(0);

                return true;

            }

        };

Answer 1

确保ResponseHandler_Review.vectorLocation1.elementAt(i)或不返回CommonFeedBean。为避免ClassCastException，请执行此操作。

for(int i=0;i<ResponseHandler_Review.vectorLocation1.size();i++) {       
 System.out.println("inside the for loop");

 if(ResponseHandler_Review.vectorLocation1.elementAt(i) instanceof CommonFeedBean) {
    // your code
 } else {
    // handle here.
 }

Answer 2

看来你vectorLocation1中的任何内容都不是CommonFeedBean。我会检查您填充该对象的位置，并确保您实际上将CommonFeedBean放入其中。

如果你想知道obj实际是什么，你可以做

System.out.println(obj.getClass().getName());

BlackBerry应用程序中的ClassCastException

2 个答案: