Fragment transactions and activity transitions

Issue

I have this scenario in my app:

One activity(A) with multiple fragments calling another activity(B) at some point.

Flow for that goes like this: F1 => F2 => F3 => B or F1 => F2 => B where F(n) represents fragment.After I finish activity B it returns me to F3 or F2 but my goal is to show user F1 so I tried sending event via event bus and replacing any other fragment with F1,note that I'm adding every fragment to backstack.So I succeed with it but if I call fragment F2 or F3 application crashes also sometimes I get "IllegalStateException: Can not perform this action after onSaveInstanceState".

So after trying a lot of approaches I simply did this :

public void onClick(View v){
 //started activity B
 //replaced current fragment with F1
}

The end result of this was seeing F1 before activity B ,and everything else worked fine without crashing.So to solve that glitch I replaced fragment 100 ms after activity B is started.

public void onClick(View v){
     //started activity B
      new Handler().(new Runable(){
      @Override
      public void run()
      {
       //replaced current fragment with F1
      } 
      },100);
    }

But I feel this is ugly way to solve this problem and I want to ask you if there is better solution?

EDIT:

I was inspired by spcial answer so I did similar thing with states.

In activity A I have two variables.

boolean wasAnotherActivityCalled=false;
String  showFragment=null;

In my fragment I have this :

   public void onClick(View v){
             //started activity B
             getActivity().wasAnotherActivityCalled=true;
             getActivity().showFragment=FragmentOne.class.getSimpleName();  
            }

in activity A I have this :

 @Override
    protected void onResumeFragments() {
        super.onResumeFragments();
        if(wasAnotherActivityCalled)
         {
            if(showFragment.equals(F1.class.getSimpleName()))
               { //do your logic here}

             wasAnotherActivityCalled=false;
             showFragment=null;
         }
 }

Solution

I have something similiar in my App. What I did was to use a simple "state-machine" where I have an int attribute which represents the current state (0 = Fragment1, 1 = Fragment2...etc) and an ArrayList with all fragments which I need. If I have to switch the fragment I also increment the state and just load the fragment from the ArrayList.

In my onPause() method I save the state in sharedPreferences() and in the onResume() method I load the state from sharedPreferences() and do a initFragment(state) where I just replace the fragmentLayout with the fragment from fragmentArray[state] :-)

With this behaviour I could handle backstack on my own, can go back and furth and save the state of the current needed fragment everytime the user changes the activity and comes back. Furthermore I don't commit the fragments into backstack because it is already handled through myself.

I hope I could help you with this.

Answered By - spcial