 Known Direct Subclasses
| PriorityQueue<E> |
A PriorityQueue holds elements on a priority heap, which orders the elements
according to their natural order or according to the comparator specified at
construction time. |
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Class Overview
AbstractQueue is an abstract class which implements some of the methods in
Queue. The provided implementations of add, remove and
element are based on offer, poll, and peek except
that they throw exceptions to indicate some error instead of returning true
or false.
Summary
| Protected Constructors |
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AbstractQueue()
Constructor to be used by subclasses.
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| Public Methods |
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boolean
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add(E o)
Adds an element to the queue.
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boolean
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addAll(Collection<? extends E> c)
Adds all the elements of a collection to the queue.
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void
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clear()
Removes all elements of the queue, leaving it empty.
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E
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element()
Returns but does not remove the element at the head of the queue.
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E
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remove()
Removes the element at the head of the queue and returns it.
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[Expand]
Inherited Methods |
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From class
java.util.AbstractCollection
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boolean
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add(E object)
Attempts to add object to the contents of this Collection
(optional).
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boolean
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addAll(Collection<? extends E> collection)
Attempts to add all of the objects contained in collection to the
contents of this Collection (optional).
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void
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clear()
Removes all elements from this Collection, leaving it empty
(optional).
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boolean
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contains(Object object)
Tests whether this Collection contains the specified object.
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boolean
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containsAll(Collection<?> collection)
Tests whether this Collection contains all objects contained in the
specified Collection.
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boolean
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isEmpty()
Returns if this Collection contains no elements.
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abstract
Iterator<E>
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iterator()
Returns an instance of Iterator that may be used to access the
objects contained by this Collection. |
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boolean
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remove(Object object)
Removes one instance of the specified object from this Collection if
one is contained (optional).
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boolean
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removeAll(Collection<?> collection)
Removes all occurrences in this Collection of each object in the
specified Collection (optional).
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boolean
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retainAll(Collection<?> collection)
Removes all objects from this Collection that are not also found in
the Collection passed (optional).
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abstract
int
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size()
Returns a count of how many objects this Collection contains.
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Object[]
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toArray()
Returns a new array containing all elements contained in this
ArrayList.
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String
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toString()
Returns the string representation of this Collection.
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From class
java.lang.Object
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boolean
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equals(Object obj)
Indicates whether some other object is "equal to" this one.
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final
Class<?>
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getClass()
Returns the runtime class of an object.
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int
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hashCode()
Returns a hash code value for the object.
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final
void
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notify()
Wakes up a single thread that is waiting on this object's monitor.
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final
void
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notifyAll()
Wakes up all threads that are waiting on this object's monitor.
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String
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toString()
Returns a string representation of the object.
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final
void
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wait(long timeout, int nanos)
Causes current thread to wait until another thread invokes the
notify() method or the
notifyAll() method for this object, or some other
thread interrupts the current thread, or a certain amount of real time has
elapsed. |
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final
void
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wait(long timeout)
Causes current thread to wait until either another thread invokes the
notify() method or the
notifyAll() method for this object, or a specified
amount of time has elapsed. |
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final
void
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wait()
Causes current thread to wait until another thread invokes the
notify() method or the
notifyAll() method for this object. |
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From interface
java.lang.Iterable
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From interface
java.util.Collection
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abstract
boolean
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add(E object)
Attempts to add object to the contents of this Collection
(optional).
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abstract
boolean
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addAll(Collection<? extends E> collection)
Attempts to add all of the objects contained in Collection to the
contents of this Collection (optional).
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abstract
void
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clear()
Removes all elements from this Collection, leaving it empty
(optional).
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abstract
boolean
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contains(Object object)
Tests whether this Collection contains the specified object.
|
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abstract
boolean
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containsAll(Collection<?> collection)
Tests whether this Collection contains all objects contained in the
specified Collection.
|
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abstract
boolean
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equals(Object object)
Compares the argument to the receiver, and returns true if they represent the
same object using a class specific comparison.
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abstract
int
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hashCode()
Returns an integer hash code for the receiver.
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abstract
boolean
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isEmpty()
Returns if this Collection contains no elements.
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abstract
Iterator<E>
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iterator()
Returns an instance of Iterator that may be used to access the
objects contained by this Collection. |
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abstract
boolean
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remove(Object object)
Removes one instance of the specified object from this Collection if
one is contained (optional).
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abstract
boolean
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removeAll(Collection<?> collection)
Removes all occurrences in this Collection of each object in the
specified Collection (optional).
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abstract
boolean
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retainAll(Collection<?> collection)
Removes all objects from this Collection that are not also found in
the Collection passed (optional).
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abstract
int
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size()
Returns a count of how many objects this Collection contains.
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abstract
<T>
T[]
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toArray(T[] a)
Returns an array containing all of the elements in this collection; the
runtime type of the returned array is that of the specified array.
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abstract
Object[]
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toArray()
Returns an array containing all of the elements in this collection.
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From interface
java.util.Queue
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abstract
E
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element()
Gets but does not remove the element at the head of the queue.
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abstract
boolean
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offer(E o)
Inserts the specified element into the queue provided that the condition
allows such an operation.
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abstract
E
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peek()
Gets but does not remove the element at the head of the queue.
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abstract
E
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poll()
Gets and removes the element at the head of the queue, or returns null if there is no element in the queue.
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abstract
E
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remove()
Gets and removes the element at the head of the queue.
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Protected Constructors
protected
AbstractQueue
()
Constructor to be used by subclasses.
Public Methods
public
boolean
add
(E o)
Adds an element to the queue.
Parameters
| o |
the element to be added to the queue. |
Returns
true if the operation succeeds, otherwise false.
public
boolean
addAll
(Collection<? extends E> c)
Adds all the elements of a collection to the queue. If the collection is the
queue itself, then an IllegalArgumentException will be thrown. If during the
process, some runtime exception is thrown, then those elements in the
collection which have already successfully been added will remain in the
queue. The result of the method is undefined if the collection is modified
during the process of the method.
Parameters
| c |
the collection to be added to the queue. |
Returns
true if the operation succeeds, otherwise false.
public
void
clear
()
Removes all elements of the queue, leaving it empty.
public
E
element
()
Returns but does not remove the element at the head of the queue.
Returns
- the element at the head of the queue.
public
E
remove
()
Removes the element at the head of the queue and returns it.
Returns
- the element at the head of the queue.