片段：从父

Question

在我的片段onCreateView方法中，我执行以下操作：

    if (view != null) {
                // Remove the view from the parent
                ((ViewGroup) view.getParent()).removeView(view);
                // Return it
                return view;
     }else{
      view = inflater.inflate(R.layout.base_activity, container, false);
    }

当我针对API级别21构建我的应用程序时，这非常正常，但是当我针对API级别23构建我的应用程序时，我遇到以下错误：

STACK_TRACE=java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.ViewGroup.removeView(android.view.View)' on a null object reference
at com.xyz.abc.core.ui.ServerErrorOverviewFragment.onCreateView(ServerErrorOverviewFragment.java:65)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1248)
at android.support.v4.app.BackStackRecord.popFromBackStack(BackStackRecord.java:958)
at android.support.v4.app.FragmentManagerImpl.popBackStackState(FragmentManager.java:1666)
at android.support.v4.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:586)
at android.support.v4.app.FragmentActivity.onBackPressed(FragmentActivity.java:169)
at android.app.Activity.onKeyUp(Activity.java:2576)
at android.view.KeyEvent.dispatch(KeyEvent.java:3171)
at android.app.Activity.dispatchKeyEvent(Activity.java:2831)
at android.support.v7.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:50)
at android.support.v7.app.AppCompatDelegateImplBase$AppCompatWindowCallbackBase.dispatchKeyEvent(AppCompatDelegateImplBase.java:224)
at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:2429)
at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:4584)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4539)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4070)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4123)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4089)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4203)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4097)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4260)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4070)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4123)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4089)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4097)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4070)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4123)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4089)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4236)
at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:4423)
at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:2480)
at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:2074)
at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:2065)
at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:2457)
at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141)
at android.os.MessageQueue.nativePollOnce(Native Method)
at android.os.MessageQueue.next(MessageQueue.java:143)
at android.os.Looper.loop(Looper.java:130)
at android.app.ActivityThread.main(ActivityThread.java:5942)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1400)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1195)

我错过了这里的事情。

Answer 1

来自http://developer.android.com/guide/components/fragments.html

的示例

public static class ExampleFragment extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.example_fragment, container, false);
    }
}

如果有任何需要做你正在做的事情，那么我认为Google指南会提到它。

在任何情况下，如果视图不为空，那么您不必做任何事情。所以它看起来像这样：

 if (view == null) {
     view = inflater.inflate(R.layout.base_activity, container, false);
 } 
return view;

此外，视图不为null的事实并不意味着视图具有父级。抛出您的空指针异常，因为view.getParent（）为null。你应该检查

if(view.getParent()!=null){
     .........
}