MyApplication.java

public class MyApplication extends Application {

    @Override
    public void onCreate(){
        super.onCreate();

        Realm.init(getApplicationContext());
        RealmConfiguration c = new RealmConfiguration.Builder().build();
        // Use below if you are in the middle of development and changing your schema.
        // RealmConfiguration config = new RealmConfiguration.Builder().deleteRealmIfMigrationNeeded().build();
        Realm.setDefaultConfiguration(c);
    }
}