CODEWITHSUNDEEP
javagwtdata-structures
helpermethod
helpermethod

Reputation: 62185

Which datastructure to store logged in users?

I'm implementing a web application and on the serverside I need to keep track of logged in users. I've implemented a simple Authentication class for this, with methods for logging in/out.

public class AuthenticationServiceImpl extends RemoteServiceServlet implements AuthenticationService {

    private final List<User> currentlyLoggedIn = new ArrayList<User>();

    @Override
    public User login(String username, String password) {
            // retrieve user from DB if exists
        // add the user to the list/set/whatever
    }

    @Override
    public void logout(User user) {
            // remove the user from the datastructure
    }
}

Now, I wonder which datastructure would be best to use? First I was thinking of a List, but as the order doesn't matter, and I need fast add/remove capabilities, I'm now thinking that a HashMap, using the username as the key and the User object as the value would be a better option. Any ideas/suggestions?

Upvotes: 0

Views: 2242

Answers (1)

dominicbri7
dominicbri7

Reputation: 2599

as the order doesn't matter, and I need fast add/remove capabilities

You've got it, an HashMap would be the perfect choice, in my opinion. Just with the fact that you can access a user object by its name, I think this is the way to go.

Upvotes: 1

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