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当我在 onSelectDate 事件被触发时尝试调用 AsyncTask 时，我得到了这个运行时错误（lang.java.nullPointerException）。我花了几个小时通过谷歌搜索来解决这个错误，但我得到了一个线索，有一个对象丢失了。这是我的代码。我也希望有人能让我摆脱这个错误。谢谢。

public class CaldroidSampleActivity extends FragmentActivity{
@Override
    protected View onCreateView(LayoutInflater inflater) {
        setRetainInstance(true);
        View v = inflater.inflate(R.layout.activity_main,null);
        final SimpleDateFormat formatter = new SimpleDateFormat("dd MMM yyyy");

        // Setup caldroid fragment
        final CaldroidFragment caldroidFragment = new CaldroidFragment();

        // Setup arguments
        Bundle args = new Bundle();
        Calendar cal = Calendar.getInstance();
        args.putInt("month", cal.get(Calendar.MONTH) + 1);
        args.putInt("year", cal.get(Calendar.YEAR));
        caldroidFragment.setArguments(args);

        FragmentTransaction t = this.getFragmentManager().beginTransaction();
        t.replace(R.id.calendar1, caldroidFragment);
        t.commit();

        // Setup listener
        final CaldroidListener listener = new CaldroidListener() {

            @Override
            public void onSelectDate(Date date, View view) {
                **callGetSelectedDateDetail(this,date);**
                Toast.makeText(context, formatter.format(date),
                        Toast.LENGTH_LONG).show();

            }

            @Override
            public void onChangeMonth(int month, int year) {
                String text = "month: " + month + " year: " + year;
                Toast.makeText(context, text, Toast.LENGTH_LONG)
                        .show();

            }

        };
        caldroidFragment.setCaldroidListener(listener);
        return v;
    }
    **protected void callGetSelectedDateDetail(CaldroidListener caldroidListener,
            Date d)** {
        executeGetSelectedDateDetail(context, d);
        // TODO Auto-generated method stub

   }
    public void executeGetSelectedDateDetail(Context c, Date d)
    {
        if(c!=null){
        new getSelectedDateDetail(c, d).execute();
        }
    }
}

public class getSelectedDateDetail extends AsyncTask<Void, Void, Void> {
@Override
    protected void onPreExecute() {
        if(context!=null){
            Log.i("onPreExecute","onPreExecute");
        }
        // TODO Auto-generated method stub
        super.onPreExecute();
    }

    @Override
    protected Void doInBackground(Void... arg0) {
        Log.i("doInBackground","ok");
        // TODO Auto-generated method stub
        return null;
    }
    @Override
    protected void onPostExecute(Void result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        if(context!=null){
            Log.i("onPostExecute","onPostExecute");
        }
    }
}

这是我在运行时遇到的错误...

04-07 04:53:24.790: E/AndroidRuntime(2247): FATAL EXCEPTION: main
04-07 04:53:24.790: E/AndroidRuntime(2247): java.lang.NullPointerException
04-07 04:53:24.790: E/AndroidRuntime(2247):     at android.view.LayoutInflater.from(LayoutInflater.java:210)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at com.bc.ema.base.BaseAdapter.<init>(BaseAdapter.java:72)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at com.bc.ema.async.getSelectedDateDetail.<init>(getSelectedDateDetail.java:32)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at com.bc.ema.view.Fragment_MySchedule.executeGetSelectedDateDetail(Fragment_MySchedule.java:124)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at com.bc.ema.view.Fragment_MySchedule.callGetSelectedDateDetail(Fragment_MySchedule.java:117)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at com.bc.ema.view.Fragment_MySchedule$1.onSelectDate(Fragment_MySchedule.java:94)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at com.caldroid.CaldroidFragment$1.onItemClick(CaldroidFragment.java:410)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at android.widget.AdapterView.performItemClick(AdapterView.java:298)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at android.widget.AbsListView.performItemClick(AbsListView.java:1100)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at android.widget.AbsListView$PerformClick.run(AbsListView.java:2749)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at android.widget.AbsListView$1.run(AbsListView.java:3423)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at android.os.Handler.handleCallback(Handler.java:725)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at android.os.Handler.dispatchMessage(Handler.java:92)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at android.os.Looper.loop(Looper.java:137)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at android.app.ActivityThread.main(ActivityThread.java:5041)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at java.lang.reflect.Method.invokeNative(Native Method)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at java.lang.reflect.Method.invoke(Method.java:511)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
04-07 04:53:24.790: E/AndroidRuntime(2247):     at dalvik.system.NativeStart.main(Native Method)
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