Method addContact

java/Chapter 8/Question8_7/User.java:52–59

(User user)

	}
	
	public boolean addContact(User user) {
		if (contacts.containsKey(user.getId())) {
			return false;
		} else {
			contacts.put(user.getId(), user);
			return true;
		}
	}
	
	public void receivedAddRequest(AddRequest req) {
		int senderId = req.getFromUser().getId();