public class ABApplication extends Application {

 @Override 
 public void onCreate() {
   super.onCreate();
   
   FirebaseApp.initializeApp(this);

   ABTesting ab = new ABTesting(new AbSettings.Builder()
       .debug(BuildConfig.DEBUG)
       .cacheExpiration(2, TimeUnit.SECONDS)
       .defaults(defaultAbValues())
       .build());
 }
}

public class MainActivity extends AppCompatActivity {

 public void fetch(View view) {
   ABApplication.get(this).getAb()
       .request(this)
       .key("onboard_navigation")
       .timeout(5, TimeUnit.SECONDS)
       .build()
       .parseValue(Parser.BOOLEAN)
       .retry(3)
       .subscribe(new Action1<Boolean>() {
         @Override public void call(Boolean value) {
           if (value) {
             startActivity(new Intent(MainActivity.this, OnboardActivity.class));
           } else {
             startActivity(new Intent(MainActivity.this, HomeActivity.class));
           }
           finish();
         }
       });
 }