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我被困住了，我会很感激有一双新的眼睛。我点击一下就可以MainActivity打电话fragment了button。它拉得很好，然后我在中添加了database调用，fragment现在它崩溃了。在我的 logcat 中，它说我在我的 onCreate 中得到一个空指针异常。这是代码和logcat。

片段代码

public class StatsFragment extends Fragment {
    public static MySmokinDatabase mySmokinDatabase;
    public static Model model;
    View view;

    public View onCreateView(LayoutInflater inflater,
            ViewGroup container,
            Bundle savedInstanceState) {

        model = MainActivity.model;
        mySmokinDatabase = new MySmokinDatabase(getActivity());

        TextView daysText = (TextView) getView().findViewById(R.id.days); 
        TextView totalText = (TextView) getView().findViewById(R.id.total); 
        TextView aveText = (TextView) getView().findViewById(R.id.ave);
        try {
            daysText.setText("" + (model.getDays())); 
            totalText.setText("" + mySmokinDatabase.getTotal());
            if (model.getDays() > 0) 
            aveText.setText("" + (float) mySmokinDatabase.getTotal() / (float) model.getDays());
        }

        catch (Exception e) {
            Log.v("*** DEBUG ***", "Error");
            System.out.print("error" + e);
        }

        // Create, or inflate the Fragment’s UI, and return it.
        // If this Fragment has no UI then return null.
        view = inflater.inflate(R.layout.stats_frag, container, false);
        return view;
    }
}

按钮处理程序

public void statisticsHandler(View view) {
    FragmentManager fm = getFragmentManager();
    FragmentTransaction ft = fm.beginTransaction();
    Log.v("*** DEBUG ***", "Statistics Handler");
    ft.replace(R.id.main_container_Id, new StatsFragment());
    ft.commit();
}

日志猫

03-27 15:40:03.767: W/dalvikvm(862): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
03-27 15:40:03.867: E/AndroidRuntime(862): FATAL EXCEPTION: main
03-27 15:40:03.867: E/AndroidRuntime(862): java.lang.NullPointerException
03-27 15:40:03.867: E/AndroidRuntime(862):  at com.example.smokin4tomsullivan.StatsFragment.onCreateView(StatsFragment.java:24)
03-27 15:40:03.867: E/AndroidRuntime(862):  at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:829)
03-27 15:40:03.867: E/AndroidRuntime(862):  at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1035)
03-27 15:40:03.867: E/AndroidRuntime(862):  at android.app.BackStackRecord.run(BackStackRecord.java:635)
03-27 15:40:03.867: E/AndroidRuntime(862):  at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1397)
03-27 15:40:03.867: E/AndroidRuntime(862):  at android.app.FragmentManagerImpl$1.run(FragmentManager.java:426)
03-27 15:40:03.867: E/AndroidRuntime(862):  at android.os.Handler.handleCallback(Handler.java:615)
03-27 15:40:03.867: E/AndroidRuntime(862):  at android.os.Handler.dispatchMessage(Handler.java:92)
03-27 15:40:03.867: E/AndroidRuntime(862):  at android.os.Looper.loop(Looper.java:137)
03-27 15:40:03.867: E/AndroidRuntime(862):  at android.app.ActivityThread.main(ActivityThread.java:4745)
03-27 15:40:03.867: E/AndroidRuntime(862):  at java.lang.reflect.Method.invokeNative(Native Method)
03-27 15:40:03.867: E/AndroidRuntime(862):  at java.lang.reflect.Method.invoke(Method.java:511)
03-27 15:40:03.867: E/AndroidRuntime(862):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
03-27 15:40:03.867: E/AndroidRuntime(862):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-27 15:40:03.867: E/AndroidRuntime(862):  at dalvik.system.NativeStart.main(Native Method)
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2 回答 2

2

view = inflater.inflate(R.layout.stats_frag, container, false);在获得您的意见之前进行设置，如下所示

在获取视图时使用getActivity()而不是。getView()

IE

   TextView daysText = (TextView) getActivity().findViewById(R.id.days); 
    TextView totalText = (TextView)  getActivity().findViewById(R.id.total); 
    TextView aveText = (TextView) getActivity().findViewById(R.id.ave);
于 2013-03-27T19:54:37.683 回答
1

在获取视图之前将其移近顶部。您正在获得 NPE，因为 findViewById 调用返回 null。

// Create, or inflate the Fragment’s UI, and return it.
// If this Fragment has no UI then return null.
view = inflater.inflate(R.layout.stats_frag, container, false);

在你抓住意见之前。然后做

TextView daysText = (TextView) view.findViewById(R.id.days); 
TextView totalText = (TextView) view.findViewById(R.id.total); 
TextView aveText = (TextView) view.findViewById(R.id.ave);
于 2013-03-27T19:59:11.397 回答