Java EE FirebaseApp name [DEFAULT] already exists

Solved the problem.

The problem was: I've called the connect method everytime a request was incoming.

Solution: Call the connect method only once. (ServletContextListener)

this for the future users, You can check whether the default app is initialized or not like this.

    FirebaseApp firebaseApp = null;
    List<FirebaseApp> firebaseApps = FirebaseApp.getApps();
    if(firebaseApps!=null && !firebaseApps.isEmpty()){
        for(FirebaseApp app : firebaseApps){
            if(app.getName().equals(FirebaseApp.DEFAULT_APP_NAME))
                firebaseApp = app;
        }
    }
    else
        firebaseApp = FirebaseApp.initializeApp(options);