Display back navigation button on toolbar / actionbar android

MainActivity.java

//////////////////////////////////
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_activity);
        setSupportActionBar(toolbar);
        ActionBar ab = getSupportActionBar();
        if ((ab != null) && (getSupportParentActivityIntent() != null)) {
          ab.setDisplayHomeAsUpEnabled(true);
        }
    }
//////////////////////////////////////////

@Override
public boolean onOptionsItemSelected(MenuItem item) {
  super.onOptionsItemSelected(item);
  switch(item.getItemId()) {
      case android.R.id.home:
          NavUtils.navigateUpFromSameTask(this);
          break;
  }
  return true;
}

manifest

// Need to define the parent activity for the back button to actually show up.  

<activity
      android:name=".MainActivity"
      android:theme="@style/RichPlayerLightTheme">
      <meta-data
          android:name="android.support.PARENT_ACTIVITY"
          android:value=".LaunchActivity" />
  </activity>