title: How 'java.lang.NullPointerException:void android.support.v7.app.ActionBar.setElevation(float)' on a null object reference'
body: <p>My code:</p>
  
  <pre><code>tabLayout.getTabAt(0).setIcon(R.drawable.ic_airport_shuttle_black_24dp)
  tabLayout.getTabAt(1).setIcon(R.drawable.ic_fingerprint_black_24dp)
  tabLayout.getTabAt(2).setIcon(R.drawable.ic_add_circle_outline_black_24dp)
  //remove Actionbar Shadow
  ActionBar actionBar = 'getSupportActionBar'
  actionBar.setElevation(0)
  </code></pre>
  
  <p>Stack trace:</p>
  
  <pre><code>java.lang.NullPointerException:void android.support.v7.app.ActionBar.setElevation(float)' on a null object reference'
  </code></pre>