Android Fragment onAttach deprecated

Question

I have updated my app to use the latest support library  version 23 0 0   I ve found out that they deprecated the onAttach   function of the Fragment class   Instead of   onAttach  Activity activity    It s now   onAttach  Context context    As my app uses the activity passed before deprecation  a possible solution i think is    Override public void onAttach Context context        super onAttach context       activity   getActivity        Would that be the correct way to do it   UPDATE   If i run a device with API lower than 23  the new onAttach   is not even being called  I hope that this is not what they intended to do   UPDATE 2   Issue has been resolved with the latest updates to the SDK   I have tested on my API 22 device and onAttach Context  is being called   Click here to follow the bug report I ve opened a couple of weeks ago and the answers from the guys at Google

User · Accepted Answer

Activity is a context so if you can simply check the context is an Activity and cast it if necessary.

@Override
public void onAttach(Context context) {
    super.onAttach(context);

    Activity a;

    if (context instanceof Activity){
        a=(Activity) context;
    }

}

Update: Some are claiming that the new Context override is never called. I have done some tests and cannot find a scenario where this is true and according to the source code, it should never be true. In all cases I tested, both pre and post SDK23, both the Activity and the Context versions of onAttach were called. If you can find a scenario where this is not the case, I would suggest you create a sample project illustrating the issue and report it to the Android team.

Update 2: I only ever use the Android Support Library fragments as bugs get fixed faster there. It seems the above issue where the overrides do not get called correctly only comes to light if you use the framework fragments.

User · Answer

The answer below is related to this deprecation warning occurring in the Fragments tutorial on the Android developer website and may not be related to the posts above     I used this code on the tutorial lesson and it did worked   public void onAttach Context context       super onAttach context        Activity activity   getActivity      I was worried that activity maybe null as what the documentation states   getActivity  FragmentActivity getActivity    Return the FragmentActivity this fragment is currently associated with  May return null if the fragment is associated with a Context instead   But the onCreate on the main activity clearly shows that the fragment was loaded and so after this method  calling get activity from the fragment will return the main activity class   getSupportFragmentManager   beginTransaction                        add R id fragment container  firstFragment  commit     I hope I am correct with this  I am an absolute newbie

User · Answer

Currently from the onAttach Fragment code  it is not clear if the Context is the current activity  Source Code  public void onAttach Context context        mCalled   true      final Activity hostActivity   mHost    null   null   mHost getActivity        if  hostActivity    null            mCalled   false          onAttach hostActivity             If you will take a look at getActivity you will see the same call         Return the Activity this fragment is currently associated with      final public Activity getActivity         return mHost    null   null   mHost getActivity        So If you want to be sure that you are getting the Activity then use  getActivity    in onAttach in your Fragment  but don t forget to check for null because if mHost is null your activity will be null

User · Answer

you are probably using android support v4 app Fragment  For this instead of onAttach method  just use getActivity   to get the FragmentActivity with which the fragment is associated with  Else you could use onAttach Context context  method

User · Answer

This is another great change from Google     The suggested modification  replace onAttach Activity activity  with onAttach Context context  crashed my apps on older APIs since onAttach Context context  will not be called on native fragments   I am using the native fragments  android app Fragment  so I had to do the following to make it work again on older APIs   lt  23    Here is what I did    Override public void onAttach Context context        super onAttach context           Code here     SuppressWarnings  deprecation    Override public void onAttach Activity activity        super onAttach activity        if  Build VERSION SDK INT  lt  Build VERSION CODES M               Code here

User · Answer

If you use the the framework fragments and the SDK version of the device is lower than 23  OnAttach Context context  wouldn t be called    I use support fragments instead  so deprecation is fixed and onAttach Context context  always gets called

User · Answer

Although it seems that in most cases it s enough to have onAttach Context   there are some phones  i e  Xiaomi Redme Note 2  where it s not being called  thus it causes NullPointerExceptions  So to be on the safe side I suggest to leave the deprecated method as well      onAttach Activity  is necessary in some Xiaomi phones  SuppressWarnings  deprecation    Override public void onAttach Activity activity        super onAttach activity        onAttach activity       Override public void onAttach Context context        super onAttach context        onAttach context      private void  onAttach Context context           do your real stuff here

User · Answer

This worked for me when i have userdefined Interface  TopSectionListener   its object activitycommander       This method gets called whenever we attach fragment to the activity  Override public void onAttach Context context        super onAttach context       Activity a getActivity        try           if context instanceof Activity             this activitycommander  TopSectionListener a       catch  ClassCastException e           throw new ClassCastException a toString

User · Answer

Override public void onAttach Context context        super onAttach context        Activity activity   context instanceof Activity    Activity  context   null

User · Answer

Download newest Support library with the sdk manager and include    compile  com android support appcompat-v7 23 1 1    in gradle app and set compile version to api 23

[android] Android Fragment onAttach() deprecated

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