package de.hs_fulda.ciip.projjpn; import java.util.HashMap; public class Customers { HashMap pool = new HashMap(); public boolean nickNameAvailable(String nickname) { User u = pool.get(nickname); if (null == u) { return true; } return false; } public User registerUser(User user) { return pool.putIfAbsent(user.nickName, user); } public User deleteUser(String userNickname) { return pool.remove(userNickname); } public User getByNickname(String nickname) { return pool.get(nickname); } public int getCountOfUsers() { return pool.size(); } }