Exit animation not working; FragmentTransaction custom animation does not work for hide

Question

I use show/hide to display a fragment that takes up part of the screen. For some reason when the fragment is shown the slide_in_left animation plays, but when the fragment is being hidden there is no animation, the fragment just disappears. I've tried using the slide_in_left animation for both exit and enter, this did not help. When a trace the code into the support package, the animation does get created and the code for displaying it is being executed. (I traced the .hide call)

FragmentManager fm = _activity.getSupportFragmentManager();
Fragment fragment = fm.findFragmentById(R.id.my_fragment);
FragmentTransaction ft = fm.beginTransaction();
ft.setCustomAnimations(R.anim.slide_in_left, R.anim.slide_out_left);
if (fragment.isHidden()) {
    ft.show(fragment);
    fragment.setUserVisibleHint(true);
} else {
    ft.hide(fragment);
}
ft.commit();

Just in case here's the xml for the slide_out_left animation

<set xmlns:android="http://schemas.android.com/apk/res/android">
    <translate android:fromXDelta="0" android:toXDelta="-50%p"
        android:duration="@android:integer/config_mediumAnimTime"/>
    <alpha android:fromAlpha="1.0" android:toAlpha="0.0"
        android:duration="@android:integer/config_mediumAnimTime" />
</set>

Edit: It's possible that the problem has something to do with the fact that my_fragment shares screen width with another fragment cotaining a webview. When .show is executed for my_fragment it becomes visible and shares space within a horizontal linear layout (how much screen width each of the two fragments takes up is determined by the weight parameter).

Answer 1

Personally for me this is a bug with the zPosition for Fragment animations.

What you see is the new fragment "appearing" this is because the new fragment is attached underneath the current one.

So when trying to animate a fragment 'Over the top' of an existing fragment, it appears like nothing is happening then the new one just 'appears'.

I have tried many work arounds, playing with zPosition (only affects windows not layouts, so no effect to fragments), onAnimationCreate() bringing the root layout to front or even on animation start and stop... seems to do nothing.

So at this point in time without writing a complete custom animation for fragment transitions, they are a bit buggy at the moment.

You may have to play with. .add(Fragment) wait for it to be added, then call .remove(Fragment) removing the old fragment, that way the new fragment is physically placed on top of the existing fragment.