Fragment not attached to a context
Solution 1
Create a fragment instance is not enough.
It needs to be attached to Activity through a transaction:
getFragmentManager()
.beginTransaction()
.replace(R.id.container_layout, fragment)
.commit();
After a successful commit, onAttach
method in the fragment is called, the view is created and then you can interact with its views.
In your case, create the fragment instance and attach it in activity onCreate
, then call sortByPopularity
later in a click event.
Read more about fragment life cycle: https://developer.android.com/guide/components/fragments
Solution 2
In my case, this problem occurred when I was calling getString()
changing this calls to getActivity().getString()
solved the problem.
Solution 3
Using commit()
can not solve the problem, we should try to find the solution in the source code of Fragment.
So, consider from the error stack you provided, the requireContext()
in Fragment was:
public final Context requireContext() {
Context context = getContext();
if (context == null) {
throw new IllegalStateException("Fragment " + this + " not attached to a context.");
}
return context;
}
This means the system will check the Context
from getContext()
, if it's null, the exception will be thrown.
So, to avoid this problem, we can check the result of getContext()
before do our business.
Solution 4
Kotlin:
My problem happened with getString()
Changing it to context.getString()
solved it
Solution 5
If you are using CountDownTimer, you may get that error cause of detaching the fragment before finishing the timer. If you are performing ui changes in onFinish callback, you should check the context that it is null or not like below;
timer = object : CountDownTimer(startTimeInMillis, 1000) {
override fun onTick(millisUntilFinished: Long) {
}
override fun onFinish() {
context?.let {
//perform ui changes here
}
}
}
timer?.start()
or you should cancel the timer before detaching fragment like below;
override fun onDestroy() {
super.onDestroy()
timer?.cancel()
}
Bo Z
Updated on July 22, 2022Comments
-
Bo Z almost 2 years
In activity in Toolbar I got a button which need to call method from fragment and update list in that fragment. Now it is an error. Calling in activity
@Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()){ case R.id.menu_sort: ListFragment listFragment = new ListFragment(); listFragment.sortByPopularity(); break; } return super.onOptionsItemSelected(item); }
Fragment code. I have found an error when Activity not attached. But nothing with context
public class ListFragment extends Fragment implements ListAdapter.ItemClickListener { /** * Needed */ RecyclerView recyclerView; View view; List<BasePojo.Result> list; ListAdapter listAdapter; public ListFragment() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { /** * Main Initialization */ view = inflater.inflate(R.layout.fragment_list, container, false); recyclerView = view.findViewById(R.id.recycler_list_detailed); recyclerView.setLayoutManager(new GridLayoutManager(getActivity(), 2)); list = new ArrayList<>(); listAdapter = new ListAdapter(list, setOnItemClickCallback()); recyclerView.setAdapter(listAdapter); RetrofitClient.getApiService().getPhotosList(getString(R.string.api_key)).enqueue(new Callback<BasePojo>() { @Override public void onResponse(Call<BasePojo> call, Response<BasePojo> response) { BasePojo basePojo = response.body(); list.addAll(basePojo.getResults()); recyclerView.getAdapter().notifyDataSetChanged(); } @Override public void onFailure(Call<BasePojo> call, Throwable t) { Log.d("tag", "Response failed" + t.toString()); } }); return view; } @Override public void onItemClick(View view, int position) { Log.v("in on click", "value " + position); } private OnItemClickListener.OnItemClickCallback setOnItemClickCallback() { OnItemClickListener.OnItemClickCallback onItemClickCallback = new OnItemClickListener.OnItemClickCallback() { @Override public void onItemClicked(View view, int position) { BasePojo.Result itemClicked = list.get(position); Bundle bundle = new Bundle(); bundle.putString("title", itemClicked.getOriginalTitle()); bundle.putString("overview", itemClicked.getOverview()); bundle.putString("release_date", itemClicked.getReleaseDate()); bundle.putString("vote_average", itemClicked.getVoteAverage().toString()); bundle.putString("poster_path", itemClicked.getPosterPath()); DetailedFragment detailedFragment = new DetailedFragment(); detailedFragment.setArguments(bundle); FragmentManager manager = getActivity().getSupportFragmentManager(); FragmentTransaction transaction = manager.beginTransaction(); transaction.replace(R.id.main_frame_list, detailedFragment); Log.d("tag", "title is 111 " + bundle.get("title")); transaction.commit(); } }; return onItemClickCallback; } @Override public void onAttachFragment(Fragment childFragment) { super.onAttachFragment(childFragment); } public void sortByPopularity() { RetrofitClient.getApiService().getPopularList(getString(R.string.api_key)).enqueue(new Callback<BasePojo>() { @Override public void onResponse(Call<BasePojo> call, Response<BasePojo> response) { BasePojo basePojo = response.body(); list.addAll(basePojo.getResults()); recyclerView.getAdapter().notifyDataSetChanged(); } @Override public void onFailure(Call<BasePojo> call, Throwable t) { Log.d("tag", "Response failed" + t.toString()); } }); } }
And here is an error
05-09 12:48:26.915 5775-5775/com.borisruzanov.popularmovies E/AndroidRuntime: FATAL EXCEPTION: main Process: com.borisruzanov.popularmovies, PID: 5775 java.lang.IllegalStateException: Fragment ListFragment{6dbd6de} not attached to a context. at android.support.v4.app.Fragment.requireContext(Fragment.java:614) at android.support.v4.app.Fragment.getResources(Fragment.java:678) at android.support.v4.app.Fragment.getString(Fragment.java:700) at com.borisruzanov.popularmovies.ListFragment.sortByPopularity(ListFragment.java:110) at com.borisruzanov.popularmovies.MainActivity.onOptionsItemSelected(MainActivity.java:47) at android.app.Activity.onMenuItemSelected(Activity.java:3204) at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:407) at android.support.v7.app.AppCompatActivity.onMenuItemSelected(AppCompatActivity.java:195) at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:108) at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:108) at android.support.v7.app.ToolbarActionBar$2.onMenuItemClick(ToolbarActionBar.java:63) at android.support.v7.widget.Toolbar$1.onMenuItemClick(Toolbar.java:203) at android.support.v7.widget.ActionMenuView$MenuBuilderCallback.onMenuItemSelected(ActionMenuView.java:780) at android.support.v7.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:822) at android.support.v7.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:171) at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:973) at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:963) at android.support.v7.widget.ActionMenuView.invokeItem(ActionMenuView.java:624) at android.support.v7.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:150) at android.view.View.performClick(View.java:5610) at android.view.View$PerformClick.run(View.java:22265) at android.os.Handler.handleCallback(Handler.java:751) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6077) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Thank you very much for your time and help. If my question looks not well please make a note and I will teach how to ask questions better
-
Bo Z almost 6 yearsI have added it with fragmentTransaction.add(R.id.main_frame_list, fragment); But to call method i would need to create instance. Maybe here is the problem?
-
Tam Huynh almost 6 yearsWhy create a new instance? Attach the fragment but keep its reference. But please put the code where you attach the fragment
-
Tam Huynh almost 6 yearsYou attach
DetailedFragment
to theListFragment
, butListFragment
is not attached to the activity yet. And another thing,DetailFragment
should be attached usinggetSupportChildFragmentManager
because it's a child ofListFragment
. -
X-Black... over 4 yearsif context == null; how do you attach the fragment the context...?
-
Jorge Barraza Z about 4 yearsFor me now it returns a "Null pointer exception" dont know why if the activity is still running
-
Jorge Alejandro Puñales almost 4 yearsBut if I define some actions and the context is null, then the behavior is not the expected. For example i want to change some text in a text view and the context is null it won't change. How can I solve this?
-
FonzTech almost 4 yearsI applied a similar solution. I do
myview.getContext().getString(bla_bla_bla)
to solve this problem. -
Shawn Wong over 3 years@JorgeAlejandroPuñales The fragment might be in abnormal state at this moment, so it might be unecessary to perform the action. To add context == null check is mainly used to avoid crash at runtime.
-
Shawn Wong over 3 yearswe could also try to use global context to get string and other resources
-
Giuseppe Garassino over 3 yearsThis was my situation... +1 because the OP was not related to CountDownTimer, but the error is the same.
-
FractalBob almost 3 years@Annie Glad it worked for you. Please mark my solution as solved.
-
Dinith Rukshan Kumara over 2 yearsMy issue occur inside a timer. This solved the problem. Thanks for the answer.
-
Shahab Saalami over 2 yearsgetContext() and getActivity() are both Nullable and will get this crash again