Java™ How to Program, Seventh Edition

17.8. Queues

Another commonly used data structure is the queue. A queue is similar to a checkout line in a supermarket—the cashier services the person at the beginning of the line first. Other customers enter the line only at the end and wait for service. Queue nodes are removed only from the head (or front) of the queue and are inserted only at the tail (or end). For this reason, a queue is a first-in, first-out (FIFO) data structure. The insert and remove operations are known as enqueue and dequeue.

Queues have many uses in computer systems. Most computers have only a single processor, so only one application at a time can be serviced. Each application requiring processor time is placed in a queue. The application at the front of the queue ...