Interface Deque

A linear collection that supports element insertion and removal at both ends. The name deque is short for "double-ended queue" and is usually pronounced "deck"

• queue是更generate的interface

Type of Operation	First Element(throw exception)	First Element(Return null/ false)	Last Element(throw expection)	Return speical value
Insert	addFirst(e)	offerFirst(e)	addLast(e)	offerLast(e)
Remove	removeFirst()	pollFirst()	removeLast()	pollLast()
Examine	getFirst()	peekFirst()	getLast()	peekLast()

• 这个是固定的！！！！

• 放是在last，拿是在first

Queue	Equivalent Deque Method
add(e)	addLast(e)
offer(e)	offerLast(e)
remove()	removeFirst()
poll()	pollFirst()
element()	getFirst()
peek()	peekFirst()

• stack只对first

Stack Method	Equivalent Deque Mathod
push(e)	offerFirst(e)
pop()	pollFirst()
peek()	peekFirst()

Summary

概念区分（逻辑层面）	内存里的存放方法	对应的java class	对应的java interface
queue(FIFO)	array/ linked list	ArrayDeque/ LinkedList	Queue
stack(LIFO)	array/ linked list	ArrayDeque/ LinkedList	Deque
deque	array/ linked list	ArrayDeque/ LinkedList	Deque