Queue

Class Overview

This kind of collection provides advanced operations compared to basic collections, such as insertion, extraction, and inspection.

Generally, a queue orders its elements by means of first-in-first-out. However, a priority queue orders its elements according to a comparator specified or the elements' natural order. Furthermore, a stack orders its elements last-in-first out.

A typical queue does not allow null to be inserted as its element, while some implementations such as LinkedList allow it. But null should not be inserted even in these implementations, since the method poll returns null to indicate that there is no element left in the queue.

Queue does not provide blocking queue methods, which would block until the operation of the method is allowed. See the BlockingQueue interface for information about blocking queue methods.

Summary

[Expand] Inherited Methods
From interface java.lang.Iterable abstract Iterator<T> iterator() Returns an Iterator for the elements in this object.
From interface java.util.Collection abstract boolean add(E object) Attempts to add object to the contents of this Collection (optional). abstract boolean addAll(Collection<? extends E> collection) Attempts to add all of the objects contained in Collection to the contents of this Collection (optional). abstract void clear() Removes all elements from this Collection, leaving it empty (optional). abstract boolean contains(Object object) Tests whether this Collection contains the specified object. abstract boolean containsAll(Collection<?> collection) Tests whether this Collection contains all objects contained in the specified Collection. abstract boolean equals(Object object) Compares the argument to the receiver, and returns true if they represent the same object using a class specific comparison. abstract int hashCode() Returns an integer hash code for the receiver. abstract boolean isEmpty() Returns if this Collection contains no elements. abstract Iterator<E> iterator() Returns an instance of Iterator that may be used to access the objects contained by this Collection. abstract boolean remove(Object object) Removes one instance of the specified object from this Collection if one is contained (optional). abstract boolean removeAll(Collection<?> collection) Removes all occurrences in this Collection of each object in the specified Collection (optional). abstract boolean retainAll(Collection<?> collection) Removes all objects from this Collection that are not also found in the Collection passed (optional). abstract int size() Returns a count of how many objects this Collection contains. abstract <T> T[] toArray(T[] array) Returns an array containing all elements contained in this Collection. abstract Object[] toArray() Returns a new array containing all elements contained in this Collection.