AbstractQueue (Drools 4.0.0.11754MR2 API) - JBoss RULES 4.0.0.11754MR2 API 英文版文档

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org.drools.util.concurrent.locks
Class AbstractQueue

java.lang.Object
  java.util.AbstractCollection
      org.drools.util.concurrent.locks.AbstractCollection
          org.drools.util.concurrent.locks.AbstractQueue

All Implemented Interfaces:: Iterable, Collection, Queue

Direct Known Subclasses:: LinkedBlockingQueue

public abstract class AbstractQueue
extends AbstractCollection
implements Queue
extends AbstractCollection
implements Queue

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(java.lang.Object) which does not permit insertion of null elements, along with methods Queue.peek(), Queue.poll(), Collection.size(), and a Collection.iterator() supporting Iterator.remove(). Typically, additional methods will be overridden as well. If these requirements cannot be met, consider instead subclassing AbstractCollection.

This class is a member of the Java Collections Framework.

Since:: 1.5
Author:: Doug Lea

Constructor Summary

protected AbstractQueue()
          Constructor for use by subclasses.

Method Summary

boolean add(Object 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.

boolean addAll(Collection c)
          Adds all of the elements in the specified collection to this queue.

void clear()
          Removes all of the elements from this queue.

Object element()
          Retrieves, but does not remove, the head of this queue.

Object remove()
          Retrieves and removes the head of this queue.

Methods inherited from class org.drools.util.concurrent.locks.AbstractCollection

toArray, toArray

Methods inherited from class java.util.AbstractCollection

contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.drools.util.concurrent.locks.Queue

offer, peek, poll

Methods inherited from interface java.util.Collection

contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray

Constructor Summary
`protected`	`AbstractQueue()` Constructor for use by subclasses.

Method Summary
`boolean`	`add(Object 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.
`boolean`	`addAll(Collection c)` Adds all of the elements in the specified collection to this queue.
`void`	`clear()` Removes all of the elements from this queue.
`Object`	`element()` Retrieves, but does not remove, the head of this queue.
`Object`	`remove()` Retrieves and removes the head of this queue.

Methods inherited from class org.drools.util.concurrent.locks.AbstractCollection
`toArray, toArray`

Methods inherited from class java.util.AbstractCollection
`contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, toString`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Methods inherited from interface org.drools.util.concurrent.locks.Queue
`offer, peek, poll`

Methods inherited from interface java.util.Collection
`contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray`

Constructor Detail

AbstractQueue

protected AbstractQueue()

Constructor for use by subclasses.

Method Detail

add

public boolean add(Object 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.

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

Specified by:: add in interface Collection
Specified by:: add in interface Queue
Overrides:: add in class AbstractCollection

Parameters:: e - the element to add
Returns:: true (as specified by Collection.add(E))
Throws:: IllegalStateException - if the element cannot be added at this time due to capacity restrictions; ClassCastException - if the class of the specified element prevents it from being added to this queue; NullPointerException - if the specified element is null and this queue does not permit null elements; IllegalArgumentException - if some property of this element prevents it from being added to this queue

remove

public Object remove()

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.

Specified by:: remove in interface Queue

Returns:: the head of this queue
Throws:: NoSuchElementException - if this queue is empty

element

public Object element()

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.

Specified by:: element in interface Queue

Returns:: the head of this queue
Throws:: NoSuchElementException - if this queue is empty

clear

public void clear()

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.

Specified by:: clear in interface Collection
Overrides:: clear in class AbstractCollection

addAll

public boolean addAll(Collection c)

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.

Specified by:: addAll in interface Collection
Overrides:: addAll in class AbstractCollection

Parameters:: c - collection containing elements to be added to this queue
Returns:: true if this queue changed as a result of the call
Throws:: ClassCastException - if the class of an element of the specified collection prevents it from being added to this queue; NullPointerException - if the specified collection contains a null element and this queue does not permit null elements, or if the specified collection is null; 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; IllegalStateException - if not all the elements can be added at this time due to insertion restrictions
See Also:: add(Object)