Java.util.concurrent Queues

Internal

• java.util.concurrent

Blocking Queue

https://docs.oracle.com/javase/10/docs/api/java/util/concurrent/BlockingQueue.html

java.util.concurrent.BlockingQueue<E> is a java.util.Queue that has operations that wait for the queue to become non-empty when retrieving an element, and wait for space to become available in the queue when storing an element. When configured with a fixed size (example ArrayBlockingQueue), it can be used as a memory sprawl control mechanisms, providing memory-safe separation between threads.

Insertion Operations:

• put() blocks if the queue is full.
• add() throws exception if the queue is full.
• offer() attempts to insert and immediately returns true if the insertion was successful or false if no space is available. offer() has an overloaded version that times out.

Removal Operations:

• take() blocks if the queue is empty.
• remove() throws exception if the queue is empty.
• poll() attempts to remove the head of the queue and returns null if the queue is empty. poll() has an overloaded version that times out.

Inspection Operations:

• peek() retrieves, but does not remove, the head of this queue, or returns null if this queue is empty.
• element() retrieves, but does not remove, the head of this queue, and throws exception if the queue is empty.

java.util.concurrent.BlockingQueue<E> has the following implementations: