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src/java.base/share/classes/java/util/AbstractQueue.java
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*** 36,55 ****
package java.util;
/**
* This class provides skeletal implementations of some {@link Queue}
* operations. The implementations in this class are appropriate when
! * the base implementation does <em>not</em> allow <tt>null</tt>
* elements. Methods {@link #add add}, {@link #remove remove}, and
* {@link #element element} are based on {@link #offer offer}, {@link
* #poll poll}, and {@link #peek peek}, respectively, but throw
! * exceptions instead of indicating failure via <tt>false</tt> or
! * <tt>null</tt> returns.
*
! * <p>A <tt>Queue</tt> implementation that extends this class must
* minimally define a method {@link Queue#offer} which does not permit
! * insertion of <tt>null</tt> elements, along with methods {@link
* Queue#peek}, {@link Queue#poll}, {@link Collection#size}, and
* {@link Collection#iterator}. Typically, additional methods will be
* overridden as well. If these requirements cannot be met, consider
* instead subclassing {@link AbstractCollection}.
*
--- 36,55 ----
package java.util;
/**
* This class provides skeletal implementations of some {@link Queue}
* operations. The implementations in this class are appropriate when
! * the base implementation does <em>not</em> allow {@code null}
* elements. Methods {@link #add add}, {@link #remove remove}, and
* {@link #element element} are based on {@link #offer offer}, {@link
* #poll poll}, and {@link #peek peek}, respectively, but throw
! * exceptions instead of indicating failure via {@code false} or
! * {@code null} returns.
*
! * <p>A {@code Queue} implementation that extends this class must
* minimally define a method {@link Queue#offer} which does not permit
! * insertion of {@code null} elements, along with methods {@link
* Queue#peek}, {@link Queue#poll}, {@link Collection#size}, and
* {@link Collection#iterator}. Typically, additional methods will be
* overridden as well. If these requirements cannot be met, consider
* instead subclassing {@link AbstractCollection}.
*
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}
/**
* Inserts the specified element into this queue if it is possible to do so
* immediately without violating capacity restrictions, returning
! * <tt>true</tt> upon success and throwing an <tt>IllegalStateException</tt>
* if no space is currently available.
*
! * <p>This implementation returns <tt>true</tt> if <tt>offer</tt> succeeds,
! * else throws an <tt>IllegalStateException</tt>.
*
* @param e the element to add
! * @return <tt>true</tt> (as specified by {@link Collection#add})
* @throws IllegalStateException if the element cannot be added at this
* time due to capacity restrictions
* @throws ClassCastException if the class of the specified element
* prevents it from being added to this queue
* @throws NullPointerException if the specified element is null and
--- 72,89 ----
}
/**
* Inserts the specified element into this queue if it is possible to do so
* immediately without violating capacity restrictions, returning
! * {@code true} upon success and throwing an {@code IllegalStateException}
* if no space is currently available.
*
! * <p>This implementation returns {@code true} if {@code offer} succeeds,
! * else throws an {@code IllegalStateException}.
*
* @param e the element to add
! * @return {@code true} (as specified by {@link Collection#add})
* @throws IllegalStateException if the element cannot be added at this
* time due to capacity restrictions
* @throws ClassCastException if the class of the specified element
* prevents it from being added to this queue
* @throws NullPointerException if the specified element is null and
*** 101,111 ****
/**
* Retrieves and removes the head of this queue. This method differs
* from {@link #poll poll} only in that it throws an exception if this
* queue is empty.
*
! * <p>This implementation returns the result of <tt>poll</tt>
* unless the queue is empty.
*
* @return the head of this queue
* @throws NoSuchElementException if this queue is empty
*/
--- 101,111 ----
/**
* Retrieves and removes the head of this queue. This method differs
* from {@link #poll poll} only in that it throws an exception if this
* queue is empty.
*
! * <p>This implementation returns the result of {@code poll}
* unless the queue is empty.
*
* @return the head of this queue
* @throws NoSuchElementException if this queue is empty
*/
*** 120,130 ****
/**
* Retrieves, but does not remove, the head of this queue. This method
* differs from {@link #peek peek} only in that it throws an exception if
* this queue is empty.
*
! * <p>This implementation returns the result of <tt>peek</tt>
* unless the queue is empty.
*
* @return the head of this queue
* @throws NoSuchElementException if this queue is empty
*/
--- 120,130 ----
/**
* Retrieves, but does not remove, the head of this queue. This method
* differs from {@link #peek peek} only in that it throws an exception if
* this queue is empty.
*
! * <p>This implementation returns the result of {@code peek}
* unless the queue is empty.
*
* @return the head of this queue
* @throws NoSuchElementException if this queue is empty
*/
*** 139,172 ****
/**
* Removes all of the elements from this queue.
* The queue will be empty after this call returns.
*
* <p>This implementation repeatedly invokes {@link #poll poll} until it
! * returns <tt>null</tt>.
*/
public void clear() {
while (poll() != null)
;
}
/**
* Adds all of the elements in the specified collection to this
* queue. Attempts to addAll of a queue to itself result in
! * <tt>IllegalArgumentException</tt>. Further, the behavior of
* this operation is undefined if the specified collection is
* modified while the operation is in progress.
*
* <p>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
! * <tt>null</tt> element) may result in only some of the elements
* having been successfully added when the associated exception is
* thrown.
*
* @param c collection containing elements to be added to this queue
! * @return <tt>true</tt> 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
* @throws NullPointerException if the specified collection contains a
* null element and this queue does not permit null elements,
* or if the specified collection is null
--- 139,172 ----
/**
* Removes all of the elements from this queue.
* The queue will be empty after this call returns.
*
* <p>This implementation repeatedly invokes {@link #poll poll} until it
! * returns {@code null}.
*/
public void clear() {
while (poll() != null)
;
}
/**
* Adds all of the elements in the specified collection to this
* queue. Attempts to addAll of a queue to itself result in
! * {@code IllegalArgumentException}. Further, the behavior of
* this operation is undefined if the specified collection is
* modified while the operation is in progress.
*
* <p>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
! * {@code null} element) may result in only some of the elements
* having been successfully added when the associated exception is
* thrown.
*
* @param c collection containing elements to be added to this queue
! * @return {@code 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
* @throws NullPointerException if the specified collection contains a
* null element and this queue does not permit null elements,
* or if the specified collection is null
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