Using context in a fragment

Question

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

User · Answer

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

User · Answer

getContext   method helps to use the Context of the class in a fragment activity

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On you fragment     Name of your Activity  getActivity    helper   On Activity  DbHelper helper   new DbHelper this

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requireContext    method is the simplest option  requireContext     Example  MyDatabase requireContext

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You can call getActivity   or   public void onAttach Context context        super onAttach context       this activity    CashActivity  context      this money   this activity money

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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

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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 lt String gt  getContext   android R layout simple list item 1  listSensorType

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Override public void onAttach Activity activity           TODO Auto-generated method stub     super onAttach activity       context activity

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Also you can use   inflater getContext      but I would prefer to use  getActivity     or  getContext

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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

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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

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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 using getActivity    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

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You can use getActivity   or getContext in Fragment   Documentation         Return the   link FragmentActivity  this fragment is currently associated with     May return   code null  if the fragment is associated with a   link Context     instead         see  requireActivity        Nullable final public FragmentActivity getActivity         return mHost    null   null    FragmentActivity  mHost getActivity        and               Return the   link Context  this fragment is currently associated with                 see  requireContext                Nullable     public Context getContext             return mHost    null   null   mHost getContext            Pro tip  Check always if getActivity  null  because it can be null when fragment is not attached to activity  Sometimes doing long operation in fragment  like fetching data from rest api  takes some time  and if user navigate to another fragment  Then getActivity will be null  And you will get NPE if you did not handle it

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getActivity   is a child of Context so that should work for you

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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

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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

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You can use getActivity    which returns the activity associated with a fragment  The activity is a context  since Activity extends Context

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With API 29  on Kotlin  I had to do  activity  applicationContext     An example would be   ContextCompat getColor activity  applicationContext    R color colorAccent

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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

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You have different options    If your minSDK  lt   21  then you can use getActivity    since this is a Context  If your minSDK is   23  then you can use getContext      If you don t need to support old versions then go with getContext

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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

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Another alternative approach is   You can get the context using   getActivity   getApplicationContext

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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

User · Answer

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

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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

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In kotlin just use activity instead of getActivity

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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

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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

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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

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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

[java] Using context in a fragment

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