Ouvrir le tiroir de navigation en cliquant sur l'icône de l'application

Je veux laisser mon utilisateur d'ouvrir le tiroir de navigation en cliquant sur l'icône de l'application. C'est mon code:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_add);
    //Show the Up button in the action bar.

    DrawerLayout mDrawerLayout = (DrawerLayout) findViewById(R.id.left_drawer);
    ActionBarDrawerToggle mDrawerToggle = new ActionBarDrawerToggle(
            this,                  /* host Activity */
            mDrawerLayout, /* DrawerLayout object */
           R.drawable.ic_drawer,  /* nav drawer icon to replace 'Up' caret */
            R.string.drawer_open,  /* "open drawer" description */
            R.string.drawer_close  /* "close drawer" description */
            ) {

        /** Called when a drawer has settled in a completely closed state. */
        public void onDrawerClosed(View view) {
            getActionBar().setTitle(R.string.title_activity_add);
        }

        /** Called when a drawer has settled in a completely open state. */
        public void onDrawerOpened(View drawerView) {
            getActionBar().setTitle(R.string.drawer_title);
        }
    };


    mDrawerLayout.setDrawerListener(mDrawerToggle);
    getActionBar().setDisplayHomeAsUpEnabled(true); //Pressing the app icon in the action bar will navigate to the parent activity.
    getActionBar().setHomeButtonEnabled(true);

}

Mais quand j'appuie sur l'icone, rien ne se passe. Où est le problème.

source d'informationauteur user2971688