 Known Direct Subclasses
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Class Overview
HashSet is an implementation of Set. All optional operations are supported,
adding and removing. The elements can be any objects.
Summary
| Public Constructors |
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HashSet()
Constructs a new empty instance of HashSet.
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HashSet(int capacity)
Constructs a new instance of HashSet with the specified capacity.
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HashSet(int capacity, float loadFactor)
Constructs a new instance of HashSet with the specified capacity and load
factor.
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HashSet(Collection<? extends E> collection)
Constructs a new instance of HashSet containing the unique elements in
the specified collection.
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| Public Methods |
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boolean
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add(E object)
Adds the specified object to this HashSet.
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void
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clear()
Removes all elements from this HashSet, leaving it empty.
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Object
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clone()
Returns a new HashSet with the same elements and size as this HashSet.
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boolean
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contains(Object object)
Searches this HashSet for the specified object.
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boolean
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isEmpty()
Returns if this HashSet has no elements, a size of zero.
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Iterator<E>
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iterator()
Returns an Iterator on the elements of this HashSet.
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boolean
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remove(Object object)
Removes an occurrence of the specified object from this HashSet.
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int
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size()
Returns the number of elements in this HashSet.
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[Expand]
Inherited Methods |
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From class java.util.AbstractSet
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boolean
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equals(Object object)
Compares the specified object to this Set and answer if they are equal.
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int
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hashCode()
Returns an integer hash code for the receiver.
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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.
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From class java.util.AbstractCollection
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boolean
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add(E object)
If the specified element is not contained within this collection, and
addition of this element succeeds, then true will be returned.
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boolean
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addAll(Collection<? extends E> collection)
Adds the objects in the specified Collection to this Collection.
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void
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clear()
Removes all the elements in this collection.
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boolean
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contains(Object object)
Searches this Collection for the specified object.
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boolean
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containsAll(Collection<?> collection)
Searches this Collection for all objects in the specified Collection.
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boolean
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isEmpty()
Returns true if the collection has no element, otherwise false.
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abstract
Iterator<E>
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iterator()
Returns an Iterator on the elements of this Collection.
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boolean
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remove(Object object)
Removes the first occurrence of the specified object from this
Collection.
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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.
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boolean
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retainAll(Collection<?> collection)
Removes all objects from this Collection that are not contained in the
specified Collection.
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abstract
int
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size()
Returns the number of elements in this Collection.
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<T>
T[]
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toArray(T[] contents)
Returns an array containing all elements contained in this Collection.
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Object[]
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toArray()
Returns a new array containing all elements contained in this Collection.
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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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Object
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clone()
Returns a new instance of the same class as the receiver, whose slots
have been filled in with the values in the slots of the receiver.
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boolean
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equals(Object o)
Compares the argument to the receiver, and returns true if they represent
the same object using a class specific comparison.
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void
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finalize()
Called by the virtual machine when there are no longer any (non-weak)
references to the receiver.
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final
Class<? extends Object>
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getClass()
Returns the unique instance of java.lang.Class which represents the class
of the receiver.
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int
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hashCode()
Returns an integer hash code for the receiver.
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final
void
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notify()
Causes one thread which is wait ing on the receiver to be
made ready to run.
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final
void
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notifyAll()
Causes all threads which are wait ing on the receiver to
be made ready to run.
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String
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toString()
Returns a string containing a concise, human-readable description of the
receiver.
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final
void
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wait(long time, int frac)
Causes the thread which sent this message to be made not ready to run
either pending some change in the receiver (as indicated by
notify or notifyAll) or the expiration of
the timeout.
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final
void
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wait(long time)
Causes the thread which sent this message to be made not ready to run
either pending some change in the receiver (as indicated by
notify or notifyAll) or the expiration of
the timeout.
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final
void
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wait()
Causes the thread which sent this message to be made not ready to run
pending some change in the receiver (as indicated by notify
or notifyAll).
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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.
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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.
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abstract
void
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clear()
Removes all elements from this Collection, leaving it empty.
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abstract
boolean
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contains(Object object)
Searches this Collection for the specified object.
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abstract
boolean
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containsAll(Collection<?> collection)
Searches this Collection for all objects 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 has no elements, a size of zero.
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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 the first occurrence of the specified object from this
Collection.
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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.
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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
contents of collection.
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abstract
int
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size()
Returns a count of how many objects are contained by this collection.
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abstract
<T>
T[]
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toArray(T[] array)
Returns an array containing all elements contained in this Collection.
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abstract
Object[]
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toArray()
Returns a new array containing all elements contained in this Collection.
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From interface java.util.Set
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abstract
boolean
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add(E object)
Adds the specified object to this Set.
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abstract
boolean
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addAll(Collection<? extends E> collection)
Adds the objects in the specified Collection which do not exist in this
Set.
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abstract
void
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clear()
Removes all elements from this Set, leaving it empty.
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abstract
boolean
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contains(Object object)
Searches this Set for the specified object.
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abstract
boolean
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containsAll(Collection<?> collection)
Searches this Set for all objects 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 Set has no elements, a size of zero.
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abstract
Iterator<E>
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iterator()
Returns an Iterator on the elements of this Set.
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abstract
boolean
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remove(Object object)
Removes any occurrence of the specified object from this Set.
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abstract
boolean
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removeAll(Collection<?> collection)
Removes all objects in the specified Collection from this Set.
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abstract
boolean
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retainAll(Collection<?> collection)
Removes all objects from this Set that are not contained in the specified
Collection.
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abstract
int
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size()
Returns the number of elements in this Set.
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abstract
<T>
T[]
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toArray(T[] array)
Returns an array containing all elements contained in this Set.
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abstract
Object[]
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toArray()
Returns an array containing all elements contained in this Set.
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Public Constructors
public
HashSet
()
Constructs a new empty instance of HashSet.
public
HashSet
(int capacity)
Constructs a new instance of HashSet with the specified capacity.
Parameters
| capacity
| the initial capacity of this HashSet
|
public
HashSet
(int capacity, float loadFactor)
Constructs a new instance of HashSet with the specified capacity and load
factor.
Parameters
| capacity
| the initial capacity |
| loadFactor
| the initial load factor
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public
HashSet
(Collection<? extends E> collection)
Constructs a new instance of HashSet containing the unique elements in
the specified collection.
Parameters
| collection
| the collection of elements to add
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Public Methods
public
boolean
add
(E object)
Adds the specified object to this HashSet.
Returns
- true when this HashSet did not already contain the object, false
otherwise
public
void
clear
()
Removes all elements from this HashSet, leaving it empty.
public
Object
clone
()
Returns a new HashSet with the same elements and size as this HashSet.
Returns
- a shallow copy of this HashSet
public
boolean
contains
(Object object)
Searches this HashSet for the specified object.
Parameters
| object
| the object to search for |
Returns
- true if
object is an element of this HashSet,
false otherwise
public
boolean
isEmpty
()
Returns if this HashSet has no elements, a size of zero.
Returns
- true if this HashSet has no elements, false otherwise
public
Iterator<E>
iterator
()
Returns an Iterator on the elements of this HashSet.
Returns
- an Iterator on the elements of this HashSet
public
boolean
remove
(Object object)
Removes an occurrence of the specified object from this HashSet.
Parameters
| object
| the object to remove |
Returns
- true if this HashSet is modified, false otherwise
public
int
size
()
Returns the number of elements in this HashSet.
Returns
- the number of elements in this HashSet
