Question

I am completely new to java, but I have urgent requirement to create a queue and thread. I am confused which queue class must be used.

Here’s the scenario:

I need to a thread to handle user events from the application layer as well as callback events from the lower middleware layer.
For this purpose, it was decided that a queue will be maintained.
Events will be posted to this queue whenever a user event or callback event occurs.
The thread polls for events in the queue and takes appropriate action.
The same queue can be written into by different classes(i.e application layer & lower layer). Hence, which queue wuld be safer, to ensure the same location is not being written into simultaneously by different classes?

Also, what is the basic one-sentence difference between a Queue, BlockingQueue and ArrayBlockingQueue and in what scenarios must each be selected?

Regards,
kiki

Answer 1

Of the three you listed, the only which is actually a class is ArrayBlockingQueue. A blocking queue is different from a normal queue in that, if an object attempts to remove the front item, it will pause execution until there is an available item to remove.

“BlockingQueue” and “Queue” are just a interfaces; you can’t instantiate them. Types of BlockingQueue that you can instantiate are ArrayBlockingQueue, LinkedBlockingQueue, etc.

Personally, I would use a LinkedBlockingQueue for this application – the advantage of using a linked list is that there’s no set max capacity, and the memory usage decreases as the queue shrinks.