ReentrantReadWriteLock blocking me from act on an object?

I have the following object:

    public class DataStructures {
    public Map<String, User> registeredUser;
    private ReadWriteLock readWriteLock;

    public DataStructures() {
        this.registeredUser = new ConcurrentHashMap<>();
        readWriteLock = new ReentrantReadWriteLock(true);
    }

    public ReadWriteLock getReadWriteLock() {
        return readWriteLock;
    }
}

I Have the following block:

    if(user != null && user.status()) {
            String userNameList = "";
            dataStructures.getReadWriteLock().readLock().lock();//ReentrantReadWriteLock
            List<User> userList = new ArrayList<>(dataStructures.registeredUser.values());
            //Will perform a sort on the userlist according their initial registration number
            Collections.sort(userList, Comparator.comparing(User::getRegistrationId));
                for (User tmpUser : userList) {
                    userNameList += tmpUser.getUsername() + " ";
                }
                connections.send(connectionId, "10 " + "7 " + userList.size() + " " + userNameList);
                dataStructures.getReadWriteLock().readLock().unlock();//ReentrantReadWriteLock
}

As you can see I locked part of this code in order to let thread read from this code at the time that no one try to write something.

also, I have the following code:

dataStructures.getReadWriteLock().writeLock().lock();//ReentrantReadWriteLock
    if(dataStructures.registeredUser.putIfAbsent(username, new User(username, password, dataStructures.registraionId)) == null) {
            connections.send(connectionId, "10 " + "01");
            dataStructures.registraionId++;
    }
    else
        connections.send(connectionId, "11 " + "01");
    dataStructures.getReadWriteLock().writeLock().unlock();//ReentrantReadWriteLock

Now, I know that when the first block of code will happen the second will wait for the first to finish, my question is if in the next block of code I will be able to read from the dataStructure object at the same time that someone will write or read from him despite I didn't mentioned any of the ReentrantReadWriteLock locks:

String username = seperate[1];
    String password = seperate[2];
    User user = dataStructures.registeredUser.get(username);

Thank you in advance!

Yes, you will be able to read from the dataStructure object at the same time someone will write or read holding the lock, because you are using thread-safe ConcurrentHashMap for the registeredUser.

If you would use normal HashMap for the registeredUser, you would be still allowed to read from the registeredUser but you would see incorect/stale data because normal HashMap is not thread-safe and you are accessing it without the lock.