Added in API level 1

AbstractQueue

abstract class AbstractQueue<E : Any!> : AbstractCollection<E>, Queue<E>
kotlin.Any
   ↳ java.util.AbstractCollection<E>
   ↳ java.util.AbstractQueue

This class provides skeletal implementations of some Queue operations. The implementations in this class are appropriate when the base implementation does not allow null elements. Methods #add, #remove, and element are based on offer, poll, and peek, respectively, but throw exceptions instead of indicating failure via false or null returns.

A Queue implementation that extends this class must minimally define a method Queue#offer which does not permit insertion of null elements, along with methods java.util.Queue#peek, Queue#poll, Collection#size, and Collection#iterator. Typically, additional methods will be overridden as well. If these requirements cannot be met, consider instead subclassing AbstractCollection.

Summary

Protected constructors

Constructor for use by subclasses.

Public methods
open Boolean
add(element: E)

Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions, returning true upon success and throwing an IllegalStateException if no space is currently available.

open Boolean
addAll(elements: Collection<E>)

Adds all of the elements in the specified collection to this queue.

open Unit

Removes all of the elements from this queue.

open E

Retrieves, but does not remove, the head of this queue.

open E

Retrieves and removes the head of this queue.

Inherited functions
Inherited properties

Protected constructors

AbstractQueue

Added in API level 1
protected AbstractQueue()

Constructor for use by subclasses.

Public methods

add

Added in API level 1
open fun add(element: E): Boolean

Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions, returning true upon success and throwing an IllegalStateException if no space is currently available.

This implementation returns true if offer succeeds, else throws an IllegalStateException.

Parameters
e the element to add
Return
Boolean true (as specified by Collection#add)
Exceptions
java.lang.UnsupportedOperationException if the add operation is not supported by this collection
java.lang.ClassCastException if the class of the specified element prevents it from being added to this queue
java.lang.NullPointerException if the specified element is null and this queue does not permit null elements
java.lang.IllegalArgumentException if some property of this element prevents it from being added to this queue
java.lang.IllegalStateException if the element cannot be added at this time due to capacity restrictions

addAll

Added in API level 1
open fun addAll(elements: Collection<E>): Boolean

Adds all of the elements in the specified collection to this queue. Attempts to addAll of a queue to itself result in IllegalArgumentException. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress.

This implementation iterates over the specified collection, and adds each element returned by the iterator to this queue, in turn. A runtime exception encountered while trying to add an element (including, in particular, a null element) may result in only some of the elements having been successfully added when the associated exception is thrown.

Parameters
c collection containing elements to be added to this queue
Return
Boolean true if this queue changed as a result of the call
Exceptions
java.lang.UnsupportedOperationException if the addAll operation is not supported by this collection
java.lang.ClassCastException if the class of an element of the specified collection prevents it from being added to this queue
java.lang.NullPointerException if the specified collection contains a null element and this queue does not permit null elements, or if the specified collection is null
java.lang.IllegalArgumentException if some property of an element of the specified collection prevents it from being added to this queue, or if the specified collection is this queue
java.lang.IllegalStateException if not all the elements can be added at this time due to insertion restrictions

See Also

    clear

    Added in API level 1
    open fun clear(): Unit

    Removes all of the elements from this queue. The queue will be empty after this call returns.

    This implementation repeatedly invokes poll until it returns null.

    Exceptions
    java.lang.UnsupportedOperationException if the clear operation is not supported by this collection

    element

    Added in API level 1
    open fun element(): E

    Retrieves, but does not remove, the head of this queue. This method differs from peek only in that it throws an exception if this queue is empty.

    This implementation returns the result of peek unless the queue is empty.

    Return
    E the head of this queue
    Exceptions
    java.util.NoSuchElementException if this queue is empty

    remove

    Added in API level 1
    open fun remove(): E

    Retrieves and removes the head of this queue. This method differs from poll only in that it throws an exception if this queue is empty.

    This implementation returns the result of poll unless the queue is empty.

    Return
    E the head of this queue
    Exceptions
    java.util.NoSuchElementException if this queue is empty