public boolean addUser(User u) {
    	//checks if user exists in database and returns false if they already exist in the database
    	if(getUser(u.getId()) != null) {
    		System.out.println("User already exists in database! User not created!");
    		return false;
    	}
    	//checks if either name string is an empty string
    	if(u.getFirstName() == null || u.getLastName() == null) {
    		System.out.println("User's first or last name is null! User not created!");
    		return false;
    	}    
    	//checks if either name string contains whitespace
    	if(whitespaceCheck(u.getFirstName()) ||whitespaceCheck(u.getLastName())) {
    		System.out.println("User's first or last name contains a space! User not created!");
    		return false;
    	}
    	//adds user if they don't exist in the database
    	users.add(u);
    	if(u.getGroup() != null)
    		joinGroup(u, u.getGroup());
    	numUsers++;
        return true;
    }