Action bar Back button not working

Question

with the help of these Android Docs.I am trying to do a action bar Back button.I get an Action Bar Back Button like these below image:

Answer 1

onCreate

{
    ...
            Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
            setSupportActionBar(toolbar);
            resetActionBar();
    ...
 }


public void resetActionBar()
    {
    getSupportActionBar().setDisplayShowHomeEnabled(true);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setHomeButtonEnabled(true);
    }

 @Override
          public void onBackPressed() {
            FragmentManager fm = getSupportFragmentManager();
            int count = fm.getBackStackEntryCount();
            if(count == 0) {
                // Do you want to close app?
                showDialog();
            }else{
                super.onBackPressed();
            }
        }


    @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            // Handle action bar item clicks here. The action bar will
            // automatically handle clicks on the Home/Up button, so long
            // as you specify a parent activity in AndroidManifest.xml.
            int id = item.getItemId();
            Log.i("coming", "comming");
            //noinspection SimplifiableIfStatement
            if(id==android.R.id.home){
                if (getSupportFragmentManager().getBackStackEntryCount() > 0)
                    onBackPressed();
                else
                    drawerLayout.openDrawer(navigationView);
                return  true;
            }

            return super.onOptionsItemSelected(item);
        }