I want to put back button on action bar (header)

final ActionBar actionBar = getSupportActionBar();
  actionBar.setDisplayHomeAsUpEnabled(true);

@Override
   public boolean onOptionsItemSelected(MenuItem item) {

       switch (item.getItemId()) {

           case android.R.id.home:
               onBackPressed();
               break;

           // create new file

       }
       return super.onOptionsItemSelected(item);
   }