我在创建ViewFlipper之前创建了一个完美的应用程序。我真的需要使用它,但现在我仍然坚持这个例外。
frag_home.java
public class Frag_home extends Fragment {
private String mParam1;
private String mParam2;
Animation fade_in, fade_out;
ViewFlipper viewFlipper;
private OnFragmentInteractionListener mListener;
public Frag_home() {
// Required empty public constructor
}
// TODO: Rename and change types and number of parameters
public static Frag_home newInstance(String param1, String param2) {
Frag_home fragment = new Frag_home();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
fade_in= AnimationUtils.loadAnimation(getActivity(), R.anim.fade_in);
fade_out=AnimationUtils.loadAnimation(getActivity(),R.anim.fade_out);
viewFlipper.setAnimation(fade_in);
viewFlipper.setAnimation(fade_out);
viewFlipper.setAutoStart(true);
viewFlipper.setFlipInterval(1000);
viewFlipper.startFlipping();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_frag_home, container, false);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
logcat的:
04-09 18:29:02.196 27863-27863/com.example.aastha.trying E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.aastha.trying, PID: 27863
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ViewFlipper.setAnimation(android.view.animation.Animation)' on a null object reference
at com.example.aastha.trying.Frag_home.onCreate(Frag_home.java:70)
at android.support.v4.app.Fragment.performCreate(Fragment.java:1951)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1029)
at android.support.v4.app.BackStackRecord.ensureFragmentsAreInitialized(BackStackRecord.java:1077)
at android.support.v4.app.BackStackRecord.beginTransition(BackStackRecord.java:1032)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:658)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5832)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
上面的代码给了我这个例外:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ViewFlipper.setAnimation(android.view.animation.Animation)' on a null object reference
我认为这部分有问题
fade_in= AnimationUtils.loadAnimation(getActivity(), R.anim.fade_in);
fade_out=AnimationUtils.loadAnimation(getActivity(),R.anim.fade_out);
我该如何解决这个问题?请帮忙。
答案 0 :(得分:0)
这是你几分钟前提出的问题,为了善待你需要初始化你的viewFlipper
onCreate()
内部方法,如下所示
@Override
public void onCreate(Bundle savedInstanceState) {
//---------Your extra codes ------
ViewFlipper viewFlipper = (ViewFlipper) findViewById(R.id.yourViewFlipperId);
//---Then only use this viewFlipper
viewFlipper.setAnimation(fade_in);
viewFlipper.setAnimation(fade_out);
}
答案 1 :(得分:0)
viewFlipper未初始化,因此为NullPointerException。您需要初始化viewFlipper才能使用它。