interface Queue<E>

Constructor

Queue<Integer> q = new LinkedList<Integer>();

Priority Queue

Based on priority heap. Order by natural ordering or user-defined comparator at the construction time.

Not synchronized. Thread safe PriorityBlockingQueue class.

O(log(n)) time for the enqueing and dequeing methods(offer,poll,remove()andadd); linear time for theremove(Object)andcontains(Object)methods; and constant time for the retrieval methods (peek,element, andsize).

constructor

PriorityQueue<Integer> pq = new PriorityQueue<Integer>();

frequently used methods

boolean - pq.add(e);
boolean - pq.offer(e);
boolean - pq.remove(object);
E - pq.poll();
E - pq.peek();
boolean - pq.contains(object);
int - pq.size();
object[] - pq.toArray();
Iterator<E> - pq.iterator();

interface Deque

双端队列（deque，全名double-ended queue）可以让你在任何一端添加或者移除元素，因此它是一种具有队列和栈性质的数据结构。

Deque<Integer> deque = new ArrayDeque<Integer>();

reference: https://www.kancloud.cn/kancloud/data-structure-and-algorithm-notes/72904