Pop the fragment backstack without playing the Pop-Animation

So Warpzit was on the right track, he just didn't address your specific issue too well. I came across the exact same issue and here is how I solved it.

First I created a static boolean variable (for simplicity's sake, lets put it in the FragmentUtils class)...

public class FragmentUtils {
    public static boolean sDisableFragmentAnimations = false;
}

Then, in EVERY fragment you have, you need to override the onCreateAnimation method...

@Override
public Animation onCreateAnimation(int transit, boolean enter, int nextAnim) {
    if (FragmentUtils.sDisableFragmentAnimations) {
        Animation a = new Animation() {};
        a.setDuration(0);
        return a;
    }
    return super.onCreateAnimation(transit, enter, nextAnim);
}

Then, when you need to clear the backstack from your activity simply do the following...

public void clearBackStack() {
    FragmentUtils.sDisableFragmentAnimations = true;
    getSupportFragmentManager().popBackStackImmediate(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
    FragmentUtils.sDisableFragmentAnimations = false;
}

And voila, a call to clearBackStack() will drop you back into the root fragment without any transition animations.

Hopefully the big G will add a less stupid way of doing this in the future.

So for the support library following works:

In the fragment which should have a custom pop animation you override the onCreateAnimation with your own custom one. You could get it and set some kind of parameter depending on what you want. There might need to be done some extra work to make it work with regular fragments.

Here is the example where I'm overriding it and changing the set duration:

@Override
public Animation onCreateAnimation(int transit, boolean enter, int nextAnim) {
    Animation anim = (Animation) super.onCreateAnimation(transit, enter, nextAnim);
    if(!enter) {
        if(anim != null) {
            anim.setDuration(0); // This doesn't seem to be called.
            return anim;
        } else {
            Animation test = new TestAnimation();
            test.setDuration(0);
            return test;
        }
    }
    return anim;
}

private class TestAnimation extends Animation {

}

The user is on the start screen with the root fragment

Lets say the root fragment is contained in Activity A.

He selects an item on the root fragment which then displays a new fragment to show details of that item. It does so using a fragment transaction that sets animations both for the push and the pop case (so when the user presses the back button, the transition is animated)

The transaction is added to the back stack. Which means that when the back button is pressed from detail fragment, the popping process is animated.

From this fragment he starts an activity which (for whatever reason) deletes the item that was just shown.

Lets say it is Activity B

When this activity finishes, I would like to return to the root fragment without showing the "pop animation" of the "detail fragment"

One way of getting this behavior is by doing this in Activity B :

Intent intent = new Intent(this, A.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
finish();

This will start the Activity A resetting it to its root state according to the documentation.(check the last paragraph in the section which says "This launch mode can also be used to good effect in conjunction with FLAG_ACTIVITY_NEW_TASK:......")

With this configuration, the animation will be present in the default case while in the special case you can control the animation using :

intent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);

Which starts new activity without any animations. If you do want any animation, you can do it using the overridePendingTransition method.

Pop the fragment backstack without playing the Pop-Animation

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