In queue, insertion and deletion happen at the opposite ends, so implementation is not as simple as stack. The queue interface is provided in java.util package and it implements the Collection interface. Since Queue is an interface you need to instantiate a concrete implementation of the interface in order to use it. It has all the functions needed to support FIFO architecture.. For concrete implementation you may use LinkedList.LinkedList implements Deque which in turn implements Queue.All of these are a part of java.util package.. For details about method with sample example you can refer FIFO based Queue implementation in Java. Queue implementation is not as straightforward as a stack implementation. Java Queue Array Implementation. You can choose between the following Queue implementations in the Java Collections API: java.util.LinkedList; java.util.PriorityQueue; LinkedList is a pretty standard queue implementation. Java Queue Implementations. First In First Out. Active 2 years ago. 76. In the previous article, we have seen the array implementation which can not be used for the large-scale applications where the queues are implemented. One of the alternatives of array implementation is linked list implementation of a queue. Live Demo. A program that demonstrates queue in Java is given as follows − Example. ArrayDeque. Queue implementations generally do not allow insertion of null elements, although some implementations, such as LinkedList, do not prohibit insertion of null. To implement queue using Arrays, we first declare an array that will hold n number of queue elements. This queue does not permit null elements. numbers.offer() - insert elements to the rear of the queue Ask Question Asked 11 years, 3 months ago. Here, we have used the LinkedList class that implements the Queue interface. This means that the elements entered first are the ones that are deleted first. Also, different operations are done at two different ends. In this article, we will discuss the implementation of Queue using Linked List. Even in the implementations that permit it, null should not be inserted into a Queue , as null is also used as a special return value by the poll method to indicate that the queue contains no elements. To implement a queue using array, create an array arr of size n and take two variables front and rear both of which will be initialized to 0 which means the queue is currently empty. The queue implements FIFO i.e. Which concurrent Queue implementation should I use in Java? Queue: [1, 2, 3] Removed Element: 1 Queue after deletion: [2, 3] In the above example, we have used the Queue interface to implement the queue in Java. Queue is an interface that extends Collection in Java. From the JavaDocs: A ConcurrentLinkedQueue is an appropriate choice when many threads will share access to a common collection. Viewed 111k times 134. First of all, the queue contains two pointers, rear, and front. Java Queue and Deque Implementations (Non-Blocking) In the following sections, you will find descriptions and the fundamental characteristics of all queue and deque implementations available in the JDK – first, the non-blocking variants, followed by the blocking ones. For each implementation, I recommend appropriate use cases.