Switching between fragments with back button

Question

Ok i have an activity with one main fragment, that has a menu on it. When a user clicks on a menu item another fragment is animated into the screen, with this code:

FragmentTransaction ft = getFragmentManager().beginTransaction();

ft.setCustomAnimations(R.anim.push_left_in, R.anim.push_left_out);
ft.hide(getFragmentManager().findFragmentByTag("menu_fragment"));

Fragment opisFragment = getFragmentManager().findFragmentByTag("opis_fragment");
if (opisFragment == null) {
    opisFragment = new OpisFragment();
    ft.add(R.id.p_container, opisFragment, "opis_fragment");
    ft.commit();
} else {
    ft.show(opisFragment);
}

Note: pr_fragment is the tag of the current fragment, the one that has the menu.

Now, this works well, but when i'm on the second fragment i want to add the functionality, that when the user clicks the back button it will show the first fragment. With this code, when i click back it exits the activity alltogether. Thank you for the help!

Glenn · Accepted Answer · 2013-12-16T00:37:07.993

4

All you need is to use addToBackStack(String name) of FragmentTransaction

// Showing menu fragment also added in backstack
FragmentTransaction ft = getFragmentManager().beginTransaction();

ft.setCustomAnimations(R.anim.push_left_in, R.anim.push_left_out)
  .add(R.id.p_container, menuFragment, "menu_fragment")
  .addToBackStack("menu_fragment")
  .commit();


// Showing opis fragment also added in backstack
FragmentTransaction ft2 = getFragmentManager().beginTransaction();

ft2.setCustomAnimations(R.anim.push_left_in, R.anim.push_left_out)
      .add(R.id.p_container, opisFragment, "opis_fragment")
      .addToBackStack("opis_fragment")
      .commit();

Assuming "opis fragment" is in foreground, when you press back button, "menu_fragment" will be displayed back to the foreground, pressing back button again will exit the activity.

edited Dec 16 '13 at 00:37

answered Dec 16 '13 at 00:30

Glenn

12,741
6
47
48

Oh wow this was rediciously simple. Just one more thing, how can i add an animation when i'm going from opis_fragment to menu_fragment (with the back button)? – Squeazer Dec 16 '13 at 00:42
1

`setCustomAnimations(int enter, int exit, int popEnter, int popExit)` of `FragmentTransaction` will do the job. – Glenn Dec 16 '13 at 00:44
See also this [question](http://stackoverflow.com/questions/5327636/animating-fragments-and-the-back-stack) – Glenn Dec 16 '13 at 00:46

score 2 · Answer 2 · answered Dec 16 '13 at 00:37

With this code, when i click back it exits the activity alltogether.

Normal because there is just your activity in your app stack. the addToBackStack() method is what you are looking for.

if (opisFragment == null) {
    opisFragment = new OpisFragment();
    ft.add(R.id.p_container, opisFragment, "opis_fragment");
    ft.addToBackStack("tag"); // <<< this line
    ft.commit();
}

From the doc :

Before you call commit(), however, you might want to call addToBackStack(), in order to add the transaction to a back stack of fragment transactions. This back stack is managed by the activity and allows the user to return to the previous fragment state, by pressing the Back button.

score 1 · Answer 3 · answered Mar 03 '17 at 11:50

in mainactivity you can check fragments count if fragments count more than one we will show back button

if(getSupportFragmentManager().getBackStackEntryCount() > 0)
            {
               mDrawerToggle.setDrawerIndicatorEnabled(false);
                getSupportActionBar().setDisplayShowHomeEnabled(false);
                getSupportActionBar().setHomeButtonEnabled(true);
                getSupportActionBar().setDisplayHomeAsUpEnabled(true);
            }
            else
            {
                mDrawerToggle.setDrawerIndicatorEnabled(true);
                getSupportActionBar().setDisplayHomeAsUpEnabled(false);
                getSupportActionBar().setHomeButtonEnabled(false);
                getSupportActionBar().setDisplayShowHomeEnabled(true);
            }

Switching between fragments with back button

3 Answers3