Initializing Timber in the Application class

App.java

public class App extends Application {

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

        Timber.plant(BuildConfig.DEBUG
                ? new Timber.DebugTree()
                : new CrashReportingTree());

        Fabric.with(this, new Crashlytics());

        FirebaseAnalytics.getInstance(this);
        
        // other things...

    }

    private class CrashReportingTree extends Timber.Tree {
        private static final String CRASHLYTICS_KEY_PRIORITY = "priority";
        private static final String CRASHLYTICS_KEY_TAG = "tag";
        private static final String CRASHLYTICS_KEY_MESSAGE = "message";

        @Override
        protected void log(int priority, String tag, String message, Throwable throwable) {
            if (priority == Log.VERBOSE || priority == Log.DEBUG) {
                return;
            }

            Throwable t = throwable != null
                    ? throwable
                    : new Exception(message);

            // Crashlytics
            Crashlytics.setInt(CRASHLYTICS_KEY_PRIORITY, priority);
            Crashlytics.setString(CRASHLYTICS_KEY_TAG, tag);
            Crashlytics.setString(CRASHLYTICS_KEY_MESSAGE, message);
            Crashlytics.logException(t);

            // Firebase Crash Reporting
            FirebaseCrash.logcat(priority, tag, message);
            FirebaseCrash.report(t);
        }
    }
}