Drawer functionality

Many recent widgets and views are not viewable using Android Studio's preview or design modes, and although there are frequent updates to rectify these issues, there will always be times when the only way to view a layout is to run it on an emulator or device. As it stands, the code we have will not compile until we enter the Java code explained in the following two parts of the exercise. Firstly, we will connect our app bar, drawer, and navigation view, and secondly, we will see how to link navigation items to the rest of our apps. The chapter concludes with a look at alternative ways to implement sliding drawers.

Activating the navigation drawer

Once the following code has been entered, it will be possible to view and test your navigation bar:

1. Open the MainActivity file and add the following lines in the onCreate() method to replace the action bar with our toolbar:

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

2. Beneath this, add the...