Standard Queue Operations

• boolean empty()
• void makeEmpty()
• E enqueue (E item)
• E dequeue()
• E peek()

java.util.Queue<E> Interface

• boolean offer (E item). Inserts the item if possible.
• E element(). Retrieves the head of the queue. Throws NuSuchElementException if empty.
• E remove(). Removes the head of the queue. Throws NoSuchElementException if empty.
• E peek(). Retrieves the head of the queue. Returns null if empty.
• E poll(). Removes the head of the queue. Returns null if empty.

Note: this interface is implemented by LinkedList<E>.

Many CS Applications

• Print Queue
• CPU Queue
• Networking Packet Queues
• Breadth-First Search
• etc.

Lecture Code

• Driver.java
• MyQueue.java
• QueueInterface.java

This code demonstrated the adapter class concept.