How to implement android Toolbar Back button

Issue

I am using a custom toolbar. I need to add back button to it. Now I am using this code to add the back button.

Toolbar toolbar = (Toolbar) getActivity().findViewById(R.id.toolbar);
        toolbar.setBackgroundColor(getResources().getColor(R.color.white));
        toolbar.setNavigationIcon(getResources().getDrawable(R.drawable.back_arrow));
        toolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                onBackPressed();
            }
        });

This works fine. I can see the back button added. But consider the case where I am in Fragment1 which has no back button. Now I move to Fragment2 and I add in Back Button. From Fragment 2 I open Fragment 3 and I add the back button again.

Now when I press back button from fragment3 to go back to fragment2 i have to check the Fragment Stack to see whether the back button is required in fragment 2 or not.

Is there any other way to handle back button automatically as we push fragments to stack?

Solution

You can handle back icon very easily. If all of your fragment are in single Activity I really recommend to handle this with following way :

first crate a abstract BaseFragment class which implement FragmentManager .OnBackStackChangedListener then put following method inside that :

  @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mainActivity = (MainActivity) getActivity();

        getFragmentManager().addOnBackStackChangedListener(this);

        shouldDisplayHomeUp();
    }

    @Override
    public void onBackStackChanged() {
        shouldDisplayHomeUp();
    }


    public boolean shouldDisplayHomeUp() {
        //Enable Up button only  if there are entries in the back stack
        boolean canBack = false;
        try {
            canBack = getFragmentManager().getBackStackEntryCount() > 0;
        } catch (Exception ex) {
//            Log.e(getClass().getCanonicalName(), ex.getMessage());getMessage
        }

        if (canBack) {
            mainActivity.drawerDisable();
        } else {
            mainActivity.drawerEnable();
        }
        return canBack;
    }

By this way disableDrawer & enableDrawer function handle your Icon and OnBackPressed method handle your BackStack Now in your activity when you press back-icon display if needed. your onBackPressed should be something like this :

 int backStackCount = getSupportFragmentManager().getBackStackEntryCount();

            if (backStackCount == 0) {
                //nothing exist in backStack OS handle it
                super.onBackPressed();
            } else {

                getSupportFragmentManager().popBackStack();
}

See full implementation here.

Answered By - Amir