How to change Back Button function in Android (Fragment)

Question

I'm developing an android application, I have a problem with the changing of back button function. How i can "replace" the default action of this button ?

I would realize a simple function that allow the user to return to the previous fragment when back button is pressed, for example :

[Main Fragment] ----> [2nd Fragment] [2nd Fragment] <---- [Main Fragment]

I have read some question like this, but i don't understand how to solve my problem.

/**
     * Diplaying fragment view for selected nav drawer list item
     * */
    private void displayView(int position) {
        // update the main content by replacing fragments
        Fragment fragment = null;
        switch (position) {
        case 0:
            fragment = new HomeFragment(getApplicationContext());
            break;
        case 1:
            fragment = new FindPeopleFragment();
            break;
        case 2:
            fragment = new PhotosFragment();
            break;
        case 3:
            fragment = new CommunityFragment();
            break;
        case 4:
            fragment = new PagesFragment();
            break;
        case 5:
            fragment = new WhatsHotFragment();
            break;

        default:
            break;
        }

This is the part of my code where i call the "new fragment". When i start up my application a new fragment is created (HomeFragment), in this frag i create a new fragment (Fragment_Detail).

What that i want is return from Fragment_Detail to HomeFragment.

I hope I was explanatory

Answer 1

Just add the addToBackStack(null). It will automatically go to the previous fragment loaded in stack.

 HomeFragment  fragment = new HomeFragment();
                FragmentManager manager = getSupportFragmentManager();
                manager.beginTransaction()
                        .replace(R.id.content, fragment,TAG)
                        .commit();

Refer addToBackStack() and refer this answer. Refer the docs