public synchronized User updateUser(User user){
		int s = userList.size();
		for(int i=0;i<s;i++){
			User u = userList.get(i);
			if(user.getAccount().equals(u.getAccount())){
				userList.set(i,u = User.clone(user));
				return u;
			}
		}
		throw new RuntimeException("user not found "+user.getAccount());
	}