How to Reverse Fragment Animations on BackStack?

Question

I thought the system would reverse animations on the backstack when the back button is pressed when using fragments using the following code:

FragmentManager         


        

Answer 1

This is as mentioned in Fragment Transaction class .

/**
     * Set specific animation resources to run for the fragments that are
     * entering and exiting in this transaction. The popEnter
     * and popExit animations will be played for enter/exit
     * operations specifically when popping the back stack.
     *
     * @param enter An animation or animator resource ID used for the enter animation on the
     *              view of the fragment being added or attached.
     * @param exit An animation or animator resource ID used for the exit animation on the
     *             view of the fragment being removed or detached.
     * @param popEnter An animation or animator resource ID used for the enter animation on the
     *                 view of the fragment being readded or reattached caused by
     *                 {@link FragmentManager#popBackStack()} or similar methods.
     * @param popExit An animation or animator resource ID used for the enter animation on the
     *                view of the fragment being removed or detached caused by
     *                {@link FragmentManager#popBackStack()} or similar methods.
     */
    @NonNull
    public abstract FragmentTransaction setCustomAnimations(@AnimatorRes @AnimRes int enter,
            @AnimatorRes @AnimRes int exit, @AnimatorRes @AnimRes int popEnter,
            @AnimatorRes @AnimRes int popExit);

so finally you can use method like this

 mFragmentManager.beginTransaction()
                        .replace(R.id.container, fragment)
                        .setCustomAnimations(R.anim.slide_left,//enter
                                             R.anim.slide_out_left,//exit
                                             R.anim.slide_right,//popEnter
                                             R.anim.slide_out_right)//popExit
                        .addToBackStack(fragment.toString())
                        .commit();