projjpn/projjpn/src/main/java/de/hs_fulda/ciip/projjpn/Customers.java

package de.hs_fulda.ciip.projjpn;

import java.util.HashMap;

public class Customers {
	HashMap<String, User> pool = new HashMap<String, User>();
	
	/**
	 * 
	 * @param nickname Is the particular Nickname free to use?
	 * @return true if nickname is Available.
	 * @return false if nickname is Available.
	 */
	public boolean nickNameAvailable(String nickname) {
		User u = pool.get(nickname);
		if (null == u) {
			return true;
		}
		return false;
	}
	
	/**
	 * 
	 * @param user New User to register.
	 * @return
	 */
	public User registerUser(User user) {
		return pool.putIfAbsent(user.nickName, user);
	}
	
	/**
	 * 
	 * @param userNickname Delete a particular User with the given nickname
	 * @return null or the deleted user.
	 */
	public User deleteUser(String userNickname) {
		return pool.remove(userNickname);
	}
	
	/**
	 * 
	 * @param nickname Find User by nickname
	 * @return
	 */
	public User getByNickname(String nickname) {
		return pool.get(nickname);
	}
	
	/**
	 * 
	 * @return Number of Users.
	 */
	public int getCountOfUsers() {
		return pool.size();
	}
}