How to fix getActionBar method may produce java.lang.NullPointerException

Question

I am using a toolbar as my actionbar in an activity. I am trying to add the method getActionBar().setDisplayHomeAsUpEnabled(true); to the Activity.java file fo

Answer 1

First off, you need to set the toolbar as the support ActionBar. Then if you're certain it's going to be there all the time, just assert it as != null. This will tell the compiler it won't be null, so the null check passes.

@Override
protected void onCreate(Bundle savedInstanceState)
{
   super.onCreate(savedInstanceState);
   setContentView(R.layout.cardviewinput);

   Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
   setSupportActionBar(toolbar);

   assert getSupportActionBar() != null;
   getSupportActionBar().setDisplayHomeAsUpEnabled(true); // it's getSupportActionBar() if you're using AppCompatActivity, not getActionBar()
}