Event when the FragmentTransaction is completed

You don't need to wait for the fragment transaction to complete, You can call

getSupportFragmentManager().executePendingTransactions();

after your commit() function call.

This will ensure that the transaction is complete.

Hei! Try this:

private OnBackStackChangedListener backStackListener =  new OnBackStackChangedListener() {

    @Override
    public void onBackStackChanged() {
        String name = "";
        int position = getSupportFragmentManager().getBackStackEntryCount();
        if(position!=0){
           FragmentManager.BackStackEntry backEntry=getSupportFragmentManager().getBackStackEntryAt(position-1);
           name=backEntry.getName();


        }
        if(position==0){
            mainActionBar();
        }
        else if(name=="someWord"){
            mainActionBar2();
        }
        else{
            mainActionBar3();
        }

    }
};
 getSupportFragmentManager().addOnBackStackChangedListener(backStackListener);

And in Transaction add tag to backStack like this:

getSupportFragmentManager().beginTransaction()
                .replace(R.id.main, SomeFragment.newInstance(some argument))
                .addToBackStack("someWord").commit();