Fragment pressing back button

Question

I am now having an activity containing fragments

[1] , [2] , [3] , [4]

If pressing buttons , [3] , it can be redirected to [4]

I would like to imp

Answer 1

Still better solution could be to follow a design pattern such that the back-button press event gets propagated from active fragment down to host Activity. So, it's like.. if one of the active fragments consume the back-press, the Activity wouldn't get to act upon it, and vice-versa.

One way to do it is to have all your Fragments extend a base fragment that has an abstract 'boolean onBackPressed()' method.

@Override
public boolean onBackPressed() {
   if(some_condition)
      // Do something
      return true; //Back press consumed.
   } else {
      // Back-press not consumed. Let Activity handle it
      return false;
   }
}

Keep track of active fragment inside your Activity and inside it's onBackPressed callback write something like this

@Override
public void onBackPressed() {
   if(!activeFragment.onBackPressed())
      super.onBackPressed();
   }
}

This post has this pattern described in detail