onAttach() not called in Fragment

My Fragment doesn't call onAttach(context) method when it launched from AppCompatActivity.

Fragment creating in XML:

<fragment
    android:id="@+id/toolbar"
    class="package.MainToolbarFragment"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    tools:layout="@layout/fragment_main_toolbar" />

But if I extends it from support.v4.Fragment, onAttach(context) call !

What could be the problem?

Of course, I can extend all fragments from v4.Fragment, but I don't want it. Is it bad practice? Also project min sdk 14.

It's not called because this method has been added in API 23. If you run your application on a device with API 23 (marshmallow) then onAttach(Context) will be called. On all previous Android Versions onAttach(Activity) will be called.

http://developer.android.com/reference/android/app/Fragment.html#onAttach(android.app.Activity)

Support libraries fragment is platform independent. Hence it works on all API versions.

While Google wants us to stop using deprecated API's

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

Is so new that it isn't widely called. You need to also implement

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    ...

For me they are identical but I like to KISS and introducing another support library tends to double my apk to about 1000kb. I only updated my SDK yesterday.

The reason the types are not interchangeable here, as they are in many instances, is that the method taking an Activity will still be called when an Activity is provided as they are both publicly visible and Activity is more specialised than (as a sub class of) Context so will take precedence.

onAttach() not called in Fragment

Related

Recent Posts