Android Studio Development Essentials: Android 6 Edition by Neil Smyth

Author:Neil Smyth [Smyth, Neil]
Language: eng
Format: epub, mobi
Publisher: eBookFrenzy
Published: 2015-12-05T23:00:00+00:00

NavigationView navigationView = (NavigationView)

findViewById(R.id.nav_view);

navigationView.setNavigationItemSelectedListener(this);

The code obtains a reference to the DrawerLayout object and then creates an ActionBarDrawerToggle object, initializing it with a reference to the current activity, the DrawerLayout object, the toolbar contained within the app bar and two strings describing the drawer opening and closing actions for accessibility purposes. The ActionBarDrawerToggle object is then assigned as the listener for the drawer and synchronized.

The code then obtains a reference to the NavigationView instance before declaring the current activity as the listener for any item selections made within the navigation drawer.

Since the current activity is now declared as the drawer listener, the onNavigationItemSelected() method is also implemented in the NavDrawerActivity.java file. The implementation of this method in the activity matches that outlined earlier in this chapter.

Finally, an additional method named onBackPressed() has been added to the activity by Android Studio. This method is added to handle situations whereby the activity has a “back” button to return to a previous activity screen. The code in this method ensures that the drawer is closed before the app switches back to the previous activity screen:

@Override

public void onBackPressed() {

DrawerLayout drawer =

(DrawerLayout) findViewById(R.id.drawer_layout);

if (drawer.isDrawerOpen(GravityCompat.START)) {

drawer.closeDrawer(GravityCompat.START);

} else {

super.onBackPressed();

}

}

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