Useful helper to handle fragment manager back stack

FragmentManagerHelper.java

package you.pkg.here;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;

/*
 * Copyright (C) 2018 InEvent, Inc. MIT License
 */
public class FragmentManagerHelper {

    /**
     * Peeks current back stack without pop.
     * -- You MUST commit attach fragments with a tag!
     * @param fragmentManager The support fragment manager v4
     * @return Fragment Top fragment at back stack
     */
    public static Fragment peekBackStack(FragmentManager fragmentManager) {
        int count = fragmentManager.getBackStackEntryCount();
        if (count > 0) {
            FragmentManager.BackStackEntry topBackStackEntry =
                    fragmentManager.getBackStackEntryAt(count - 1);
            String tag = topBackStackEntry.getName();

            if (tag != null) {
                return fragmentManager.findFragmentByTag(tag);
            }
        }

        return null;
    }

    /**
     * Commits a new fragment, adds current one to back stack and call `onPause();` on
     * current fragment.
     * @param current Current fragment
     * @param fragmentManager The support fragment manager v4
     * @param containerId The id of the container to be used
     * @param fragment The fragment to be attached
     * @param tag The fragment's tag
     */
    public static void pushStackAndPause(Fragment current, FragmentManager fragmentManager, int containerId, Fragment fragment, String tag) {
        fragmentManager.beginTransaction()
                .replace(containerId, fragment, tag)
                .addToBackStack(current.getTag())
                .commit();
        current.onPause();
    }

    /**
     * Pops back stack and resume the fragment
     * @param fragmentManager The support fragment manager v4
     */
    public static void popBackStackAndResume(FragmentManager fragmentManager) {
        Fragment fragment = FragmentManagerHelper.peekBackStack(fragmentManager);
        fragmentManager.popBackStackImmediate();
        if (fragment != null) {
            fragment.onResume();
        }
    }

    /**
     * Pops back stack to specific position, resuming all fragments on each stack count
     * @param fragmentManager The support fragment manager v4
     * @param pos The final position of the stack
     */
    public static void popBackStackAndResume(FragmentManager fragmentManager, int pos) {
        while (fragmentManager.getBackStackEntryCount() > pos && fragmentManager.getBackStackEntryCount() > 0) {
            FragmentManagerHelper.popBackStackAndResume(fragmentManager);
        }
    }

}