Comprehensive Guide to Java Queue Family: 18 Types, Interfaces, and Implementations

In this tutorial the author introduces the Java Queue family, highlighting that 18 different queue types exist and presenting the most complete and detailed explanation available.

Main contents include:

Self‑introduction of Queue as a FIFO data structure and its relation to List , Set , and Map within java.util .

Real‑world scenarios for queues (e.g., restaurant waiting lists, mailboxes, RabbitMQ, UDP).

Classification of the 18 queues into three categories: interfaces, abstract classes, and concrete classes, with an inheritance diagram.

Detailed explanation of the Queue interface, its core methods (add/offer, remove/poll, element/peek) and their exception‑or‑special‑value behavior.

Comprehensive coverage of the Deque interface, its methods, and its dual role as a stack.

Analysis of AbstractQueue with source code for add , remove , and element methods.

Examination of BlockingQueue and its 10 core methods, insertion/removal/blocking semantics, and common implementations (e.g., ArrayBlockingQueue , LinkedBlockingQueue , PriorityBlockingQueue , DelayQueue ).

Discussion of BlockingDeque , its methods, and implementations such as LinkedBlockingDeque .

Explanation of TransferQueue (mission‑critical delivery), its methods ( transfer , tryTransfer , etc.), and implementations like LinkedTransferQueue .

Insights into PriorityQueue and PriorityBlockingQueue , including sorting behavior and custom comparators.

Overview of DelayQueue for time‑based scheduling, with sample code.

Additional concrete classes such as LinkedList , ArrayDeque , ConcurrentLinkedQueue , ConcurrentLinkedDeque , SynchronousQueue , and their thread‑safety characteristics.

Code examples are presented in pre blocks, preserving the original formatting, for instance:

public boolean add(E e) {
    if (offer(e))
        return true;
    else
        throw new IllegalStateException("Queue full");
}

The article concludes by emphasizing the thoroughness of the coverage and encouraging readers to study the official Java documentation, diagrams, and demos provided.