Using context in a fragment
JavaAndroidAndroid FragmentsAndroid ContextJava Problem Overview
How can I get the context in a fragment?
I need to use my database whose constructor takes in the context, but getApplicationContext()
and FragmentClass.this
don't work so what can I do?
Database constructor
public Database(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
Java Solutions
Solution 1 - Java
You can use getActivity()
, which returns the activity associated with a fragment
.
The activity is a context
(since Activity
extends Context
).
Solution 2 - Java
To do as the answer above, you can override the onAttach
method of fragment:
public static class DummySectionFragment extends Fragment{
...
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
DBHelper = new DatabaseHelper(activity);
}
}
Solution 3 - Java
The easiest and most precise way to get the context of the fragment that I found is to get it directly from the ViewGroup
when you call onCreateView
method at least here you are sure not to get null for getActivity()
:
public class Animal extends Fragment {
Context thiscontext;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
thiscontext = container.getContext();
Solution 4 - Java
Always use the getActivity() method to get the context of your attached activity, but always remember one thing: Fragments are slightly unstable and getActivity
returns null some times, so for that, always check the isAdded() method of fragment before getting context by getActivity()
.
Solution 5 - Java
Previously I'm using onAttach (Activity activity)
to get context
in Fragment
>Problem
The onAttach (Activity activity)
method was deprecated in API level 23.
>Solution
Now to get context in Fragment
we can use onAttach (Context context)
>onAttach (Context context)
- Called when a fragment is first attached to its
context
.onCreate(Bundle)
will be called after this.
>Documentation
/**
* Called when a fragment is first attached to its context.
* {@link #onCreate(Bundle)} will be called after this.
*/
@CallSuper
public void onAttach(Context context) {
mCalled = true;
final Activity hostActivity = mHost == null ? null : mHost.getActivity();
if (hostActivity != null) {
mCalled = false;
onAttach(hostActivity);
}
}
SAMPLE CODE
public class FirstFragment extends Fragment {
private Context mContext;
public FirstFragment() {
// Required empty public constructor
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
mContext=context;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rooView=inflater.inflate(R.layout.fragment_first, container, false);
Toast.makeText(mContext, "THIS IS SAMPLE TOAST", Toast.LENGTH_SHORT).show();
// Inflate the layout for this fragment
return rooView;
}
}
##NOTE
We can also use getActivity()
to get context
in Fragments
but getActivity()
can return null
if the your fragment
is not currently attached to a parent activity
,
Solution 6 - Java
The correct way is to use
requireContext()
and the example
ContextCompat.getColor(requireContext(), R.color.colorAccent),
Solution 7 - Java
@Override
public void onAttach(Activity activity) {
// TODO Auto-generated method stub
super.onAttach(activity);
context=activity;
}
Solution 8 - Java
requireContext() method is the simplest option
requireContext()
Example
MyDatabase(requireContext())
Solution 9 - Java
You could also get the context from the inflater
parameter, when overriding onCreateView
.
public static class MyFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
/* ... */
Context context = inflater.getContext();
/* ... */
}
}
Solution 10 - Java
Another alternative approach is:
You can get the context using:
getActivity().getApplicationContext();
Solution 11 - Java
to get the context inside the Fragment will be possible using getActivity()
:
public Database()
{
this.context = getActivity();
DBHelper = new DatabaseHelper(this.context);
}
- Be careful, to get the
Activity
associated with the fragment usinggetActivity()
, you can use it but is not recommended it will cause memory leaks.
I think a better aproach must be getting the Activity
from the onAttach()
method:
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
context = activity;
}
Solution 12 - Java
getContext()
came in API 23. Replace it with getActivity() everywhere in the code.
See if it fixes the error. Try to use methods which are in between the target and minimun API level, else this error will come in place.
Solution 13 - Java
Since API level 23 there is getContext()
but if you want to support older versions you can use getActivity().getApplicationContext()
while I still recommend using the support version of Fragment
which is android.support.v4.app.Fragment
.
Solution 14 - Java
For Kotlin you can use context
directly in fragments. But in some cased you will find an error like
> Type mismatch: inferred type is Context? but Context was expected
for that you can do this
val ctx = context ?: return
textViewABC.setTextColor(ContextCompat.getColor(ctx, android.R.color.black))
Solution 15 - Java
getActivity()
is a child of Context so that should work for you
Solution 16 - Java
You have different options:
- If your minSDK <= 21, then you can use
getActivity()
, since this is aContext
. - If your minSDK is >=23, then you can use
getContext()
.
If you don't need to support old versions then go with getContext()
.
Solution 17 - Java
Use fragments from Support Library -
android.support.v4.app.Fragment
and then override
void onAttach (Context context) {
this.context = context;
}
This way you can be sure that context will always be a non-null value.
Solution 18 - Java
In kotlin just use activity
instead of getActivity()
Solution 19 - Java
You can use getActivity() method to get context or You can use getContext() method .
View root = inflater.inflate(R.layout.fragment_slideshow, container, false);
Context c = root.getContext();
I hope it helps!
Solution 20 - Java
safe way to get context in fragment
if(isAdded){
requireActivit();//this is your context
}
Solution 21 - Java
The simple way is to use getActivity()
. But I think the major confusion of using the getActivity()
method to get the context here is a null pointer exception.
For this, first check with the isAdded()
method which will determine whether it's added or not, and then we can use the getActivity()
to get the context of Activity.
Solution 22 - Java
Ideally, you should not need to use globals. The fragment has different notifications, one of them being onActivityCreated. You can get the instance of the activity in this lifecycle event of the fragment.
Then: you can dereference the fragment to get activity, context or applicationcontext as you desire:
this.getActivity()
will give you the handle to the activity
this.getContext()
will give you a handle to the context
this.getActivity().getApplicationContext()
will give you the handle to the application context. You should preferably use the application context when passing it on to the db.
Solution 23 - Java
You can call getActivity()
or,
public void onAttach(Context context) {
super.onAttach(context);
this.activity = (CashActivity) context;
this.money = this.activity.money;
}
Solution 24 - Java
public class MenuFragment extends Fragment implements View.OnClickListener {
private Context mContext;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
FragmentMenuBinding binding=FragmentMenuBinding.inflate(inflater,container,false);
View view=binding.getRoot();
mContext=view.getContext();
return view;
}
}
Solution 25 - Java
I think you can use
public static class MyFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
Context context = getActivity.getContext();
}
}
Solution 26 - Java
I need context for using arrayAdapter IN fragment, when I was using getActivity error occurs but when i replace it with getContext it works for me
listView LV=getView().findViewById(R.id.listOFsensors);
LV.setAdapter(new ArrayAdapter<String>(getContext(),android.R.layout.simple_list_item_1 ,listSensorType));
Solution 27 - Java
On you fragment
((Name_of_your_Activity) getActivity()).helper
On Activity
DbHelper helper = new DbHelper(this);
Solution 28 - Java
Inside fragment for kotlin sample would help someone
textViewStatus.setTextColor(ContextCompat.getColor(context!!, R.color.red))
if you use databinding;
bindingView.textViewStatus.setTextColor(ContextCompat.getColor(context!!, R.color.red))
Where bindingView is initialized in onCreateView like this
private lateinit var bindingView: FragmentBookingHistoryDetailBinding
bindingView = DataBindingUtil.inflate(inflater, R.layout.your_layout_xml, container, false)
Solution 29 - Java
You can use getActivity(), which returns the activity associated with a fragment. The activity is a context (since Activity extends Context).
be careful: getActivity() can return null if it is called before onAttach of the respective fragment.
2.or
The easiest and most precise way to get the context of the fragment that I found is to get it directly from the ViewGroup when you call onCreateView method at least here you are sure not to get null for getActivity():
public class Animal extends Fragment {
Context thiscontext;
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState)
{
thiscontext = container.getContext();
//...
//...
//...
}
Solution 30 - Java
In Kotlin you can use this: requireActivity().applicationContext
Solution 31 - Java
androidx.fragment.app.Fragment
@NonNull
public final android.content.Context requireContext()
Return the Context the fragment is currently associated with.
Since: getActivity and Context can be null, it is good practice to use requireContext() as it can't be null.