我该如何管理hashmap中的队列？

import java.util.HashMap;
import java.util.LinkedList;
import java.util.Queue;

public class HashMapQueueManager {
    private HashMap<String, Queue<String>> queueMap;

    public HashMapQueueManager() {
        queueMap = new HashMap<>();
    }

    public void addQueue(String queueId) {
        Queue<String> queue = new LinkedList<>();
        queueMap.put(queueId, queue);
    }

    public Queue<String> getQueue(String queueId) {
        return queueMap.get(queueId);
    }

    public void enqueue(String queueId, String element) {
        Queue<String> queue = queueMap.get(queueId);
        if (queue != null) {
            queue.add(element);
        }
    }

    public String dequeue(String queueId) {
        Queue<String> queue = queueMap.get(queueId);
        if (queue != null) {
            return queue.poll();
        }
        return null;
    }

    public String peek(String queueId) {
        Queue<String> queue = queueMap.get(queueId);
        if (queue != null) {
            return queue.peek();
        }
        return null;
    }

    public static void main(String[] args) {
        HashMapQueueManager manager = new HashMapQueueManager();
        manager.addQueue("queue1");
        manager.enqueue("queue1", "element1");
        manager.enqueue("queue1", "element2");
        System.out.println(manager.dequeue("queue1")); // Output: element1
        System.out.println(manager.peek("queue1")); // Output: element2
    }
}