xml:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
android:id="@+id/the_fragment"
android:name="com.example.MyFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
tools:layout="@layout/fragment_my"/>
<Button
android:id = "@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Show/Hide"/>
</RelativeLayout>
代码:
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mMyFragment = (MyFragment) getChildFragmentManager()
.findFragmentById(R.id.the_fragment);
((Button)view.findViewById(R.id.button)).setOnClickListener(view->{
if (...){
//hide
getChildFragmentManager().beginTransaction()
.setCustomAnimations(R.animator.slide_in_from_bottom, R.animator.slide_out_to_bottom)
.hide(mMyFragment)
.commit();
}else{
//show
getChildFragmentManager().beginTransaction()
.setCustomAnimations(R.animator.slide_in_from_bottom, R.animator.slide_out_to_bottom)//in this line the app crash
.show(mMyFragment)
.commit();
}
});
}
发生错误:
Process: by.gramophone.develop, PID: 21508
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.ViewGroup.startViewTransition(android.view.View)' on a null object reference
at android.support.v4.app.FragmentManagerImpl.completeShowHideFragment(FragmentManager.java:1700)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1797)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:792)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2596)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2383)
at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2338)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2245)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:703)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
更新:
但是,如果我删除.setCustomAnimations(R.animator.slide_in_from_bottom, R.animator.slide_out_to_bottom)
,就不会发生错误