ArrayDeque 的 Stack 和同步装饰器之间的区别

Question

I want to have LIFO effect and I want it to be synchronized. Does anyone know which one of these two implementations I should use? Been googling for a while, still no good answer.

Bottom line: what are differences, why use one over another, why is it said to favor arrayDequeue?

Answer 1

From question:

why is it said to favor arrayDequeue?

It is not said to favor ArrayDeque (a class).

It is said that you should favor Deque (an interface) over Stack (a class), because you should program to an interface , allowing you to substitute the implementation without otherwise changing your code.

The "it is said..." is right there in the javadoc of Stack :

A more complete and consistent set of LIFO stack operations is provided by the Deque interface and its implementations, which should be used in preference to this class.

The Java Runtime Library comes with the following choices of implementation for a Deque :

• ArrayDeque - generally best choice for single-threaded use
• ConcurrentLinkedDeque - generally best choice for multi-threaded use
• LinkedBlockingDeque - if you need stack with size limit
• LinkedList - if stack can grow big, and you want to reclaim space as it shrinks

LinkedBlockingDeque uses locks, which is similar to using synthronized , but none of the others use synchronized . The way ConcurrentLinkedDeque is implemented to be thread-safe has proven to perform better than an implementation using synchronized . ArrayDeque is faster than Stack because it is not using synchronized , so is better for non-thread-safe code.

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See also: Why should I use Deque over Stack?
See also: Why is Java Vector (and Stack) class considered obsolete or deprecated?