Queue vs Dequeue in java

Question

What is the difference between them? I know that

A queue is designed to have elements inserted at the end of the queue, and elements removed from the beginning of the queue. Where as Dequeue represents a queue where you can insert and remove elements from both ends of the queue.

But which is more efficient?

Plus what's the difference between them two? Because I have a bit of knowledge about them, what I said above, but I would like to know more about them.

I've already saw javadoc but i still didn't get much. so that's why i asked here, if someone can help me... — , Aug 07 '16 at 08:17
Like Thor said. Plus: hit google with both `grepcode java queue` and `grepcode java dequeue` to see the implementational differences. — JayC667, Aug 07 '16 at 08:17
@ Junyoung Clare Jang I mean the speed or Which one takes more memory? — , Aug 07 '16 at 08:18

Dawood ibn Kareem · Answer 1 · 2019-01-29T06:24:58.090

68

Deque is short for "double ended queue". With an ordinary queue, you add things to one end and take them from the other. With a double ended queue, you can add things to either end, and take them from either end. That makes it a bit more versatile; for example, you could use it as a stack if you wanted to.

In terms of efficiency, it really depends on the implementation. But generally speaking, you wouldn't expect a deque to outperform a queue, because a (single ended) queue could be implemented in a way that doesn't allow objects to be added or removed at the "wrong" end. Whereas any implementation of a deque would also work as an implementation of a queue.

edited Jan 29 '19 at 06:24

answered Aug 07 '16 at 09:52

Dawood ibn Kareem

77,785
15
98
110

I did not understand... What is better for efficiency ? Can we use deque all times instead of queue? – Bogdan Feb 28 '21 at 07:28
4

@byteis8bits My answer says that a deque WON'T be more efficient than a queue. – Dawood ibn Kareem Mar 01 '21 at 03:53

score 7 · Answer 2 · answered Aug 07 '16 at 08:37

Deque and queue are abstract data types that can be implemented in different ways. To talk about performance you have to specify which implementations you want to compare and which operation(s) you're interested in. Even better, do the benchmark yourself with the workload your application has and in the environment you're going to use (hardware, operating system, JVM version).

Since every deque is also a queue, in general you can say that deques can be at most as good as a queues.

Queue vs Dequeue in java

2 Answers2