ListActivity 设置adapter异常问题

Question

是这样的。我从SimpleAdapter继承了一个MySimpleAdapter，同时也继承了一个ListActivity， 并将MySimpleAdapter设置为这个ListActivity的adapter,此时可以正常显示数据，但是发现数据量多余一屏时，滚动屏幕无法更新list。于是我就添加了一个onContentChanged()的函数，发现一添加这个函数（哪怕一句话也不写），程序就会crash，
09-02 17:14:30.694 E/AndroidRuntime( 5794): Caused by: java.lang.NullPointerException
09-02 17:14:30.694 E/AndroidRuntime( 5794):  at ndroid.app.ListActivity.setListAdapter(ListActivity.java:265)
有人遇到过这种问题吗，太纠结了

Answer 1

屏幕滚动和onContentChanged没关系啊。
数据不更新，应该是你的MySimpleAdapter实现问题。

Answer 2

    final class MySimpleAdapter extends SimpleAdapter {
        private String [] mFrom;
        private int[] mTo;
        protected LayoutInflater mInflater;
        private int mResourcesId;
        private List<Map<String, Object>> mListData = null;        SpeedDialAdapter(Context context, List<Map<String, Object>> items,
                int resourceId, String[] from, int []to ) {            super(context, items, resourceId, from, to);
            mInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            mListData = items;
            mResourcesId = resourceId;
            mTo = to;
        }        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View v;
            if(null == convertView)
            {
                Log.i(TAG,"geView");                v = mInflater.inflate(mResourcesId, parent, false);
                int count = mTo.length;
                View[] views = new View[count];                for(int i=0;i<count;i++)
                {
                    views[i] = v.findViewById(mTo[i]);
                }
                v.setTag(views);
                //if(mListData)
                Map<String, Object> map = mListData.get(position);
                Log.i(TAG, "position is " + position);
                String label = map.get(LABEL_KEY) == null? "": map.get("label").toString();
                String number = map.get(NUMBER_KEY) == null? "": map.get("number").toString();
                String count_label = map.get("count")== null ? "" :map.get("count").toString();
                String line = map.get("line") == null? "":map.get("line").toString();                if(number.equals(""))
                {
                    setViewImage(((ImageView)views[ICON_INDEX]),R.drawable.add_icn);                }else
                {
                    setViewImage(((ImageView)views[ICON_INDEX]),R.drawable.delete_icn);
                }                if(line1.equals(""))
                {
                    setViewText(((TextView)views[LINE1_INDEX]),number);
                }
                else
                {
                    if(number.equals(""))
                    {
                        Log.i(TAG,"Error,it should not exist");
                    }
                    setViewText(((TextView)views[LINE1_INDEX]),line);
                    setViewText(((TextView)views[NUMBER_INDEX]),number);
                    setViewText(((TextView)views[LABEL_INDEX]),label);                }                if(count_label.equals(""))
                {
                   Log.i(TAG,"no Label");
                   setViewText(((TextView)views[COUNT_INDEX]),String.valueOf(position));
                }
                else
                {
                    setViewText(((TextView)views[COUNT_INDEX]),count_label);
                }                return v;            }else
            {
                return convertView;
            }        }
        @Override
        public int getCount()
        {
            return mListData.size();
        }
        @Override
        public Object getItem(int position) {
            return mListData.get(position);
        }
    }
那自己实现SimpleAdapter需要注意什么？ 代码贴上了，帮忙看下问题在哪儿吧，多谢了～

Answer 3

用个线程去取数据，得到数据再更新界面，好像有个contentProvider,找个android自带的例子看

Answer 4

解决了。 if(null == convertView)else时，也要对convertView更新数据。