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Préférences
Moteurs de recherche
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JavaTM 2 Platform Std. Ed. v1.4.2
java.util
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Method Summary | |
boolean |
add(Object o)
Adds the specified element to this set if it is not already present (optional operation). |
boolean |
addAll(Collection c)
Adds all of the elements in the specified collection to this set if they're not already present (optional operation). |
void |
clear()
Removes all of the elements from this set (optional operation). |
boolean |
contains(Object o)
Returns true if this set contains the specified element. |
boolean |
containsAll(Collection c)
Returns true if this set contains all of the elements of the specified collection. |
boolean |
equals(Object o)
Compares the specified object with this set for equality. |
int |
hashCode()
Returns the hash code value for this set. |
boolean |
isEmpty()
Returns true if this set contains no elements. |
Iterator |
iterator()
Returns an iterator over the elements in this set. |
boolean |
remove(Object o)
Removes the specified element from this set if it is present (optional operation). |
boolean |
removeAll(Collection c)
Removes from this set all of its elements that are contained in the specified collection (optional operation). |
boolean |
retainAll(Collection c)
Retains only the elements in this set that are contained in the specified collection (optional operation). |
int |
size()
Returns the number of elements in this set (its cardinality). |
Object[] |
toArray()
Returns an array containing all of the elements in this set. |
Object[] |
toArray(Object[] a)
Returns an array containing all of the elements in this set; the runtime type of the returned array is that of the specified array. |
Method Detail |
public int size()
size
in interface Collection
public boolean isEmpty()
isEmpty
in interface Collection
public boolean contains(Object o)
e
such that (o==null ? e==null :
o.equals(e))
.
contains
in interface Collection
o
- element whose presence in this set is to be tested.
ClassCastException
- if the type of the specified element
is incompatible with this set (optional).
NullPointerException
- if the specified element is null and this
set does not support null elements (optional).public Iterator iterator()
iterator
in interface Collection
public Object[] toArray()
toArray
in interface Collection
public Object[] toArray(Object[] a)
toArray
in interface Collection
a
- the array into which the elements of this set are to
be stored, if it is big enough; otherwise, a new array of the
same runtime type is allocated for this purpose.
ArrayStoreException
- the runtime type of a is not a supertype
of the runtime type of every element in this set.
NullPointerException
- if the specified array is null.public boolean add(Object o)
o
, to this set if this set contains no element
e
such that (o==null ? e==null :
o.equals(e))
. If this set already contains the specified
element, the call leaves this set unchanged and returns false.
In combination with the restriction on constructors, this ensures that
sets never contain duplicate elements.The stipulation above does not imply that sets must accept all elements; sets may refuse to add any particular element, including null, and throwing an exception, as described in the specification for Collection.add. Individual set implementations should clearly document any restrictions on the the elements that they may contain.
add
in interface Collection
o
- element to be added to this set.
UnsupportedOperationException
- if the add method is not
supported by this set.
ClassCastException
- if the class of the specified element
prevents it from being added to this set.
NullPointerException
- if the specified element is null and this
set does not support null elements.
IllegalArgumentException
- if some aspect of the specified element
prevents it from being added to this set.public boolean remove(Object o)
e
such that
(o==null ? e==null : o.equals(e))
, if the set contains
such an element. Returns true if the set contained the
specified element (or equivalently, if the set changed as a result of
the call). (The set will not contain the specified element once the
call returns.)
remove
in interface Collection
o
- object to be removed from this set, if present.
ClassCastException
- if the type of the specified element
is incompatible with this set (optional).
NullPointerException
- if the specified element is null and this
set does not support null elements (optional).
UnsupportedOperationException
- if the remove method is
not supported by this set.public boolean containsAll(Collection c)
containsAll
in interface Collection
c
- collection to be checked for containment in this set.
ClassCastException
- if the types of one or more elements
in the specified collection are incompatible with this
set (optional).
NullPointerException
- if the specified collection contains one
or more null elements and this set does not support null
elements (optional).
NullPointerException
- if the specified collection is
null.contains(Object)
public boolean addAll(Collection c)
addAll
in interface Collection
c
- collection whose elements are to be added to this set.
UnsupportedOperationException
- if the addAll method is
not supported by this set.
ClassCastException
- if the class of some element of the
specified collection prevents it from being added to this
set.
NullPointerException
- if the specified collection contains one
or more null elements and this set does not support null
elements, or if the specified collection is null.
IllegalArgumentException
- if some aspect of some element of the
specified collection prevents it from being added to this
set.add(Object)
public boolean retainAll(Collection c)
retainAll
in interface Collection
c
- collection that defines which elements this set will retain.
UnsupportedOperationException
- if the retainAll method
is not supported by this Collection.
ClassCastException
- if the types of one or more elements in this
set are incompatible with the specified collection
(optional).
NullPointerException
- if this set contains a null element and
the specified collection does not support null elements
(optional).
NullPointerException
- if the specified collection is
null.remove(Object)
public boolean removeAll(Collection c)
removeAll
in interface Collection
c
- collection that defines which elements will be removed from
this set.
UnsupportedOperationException
- if the removeAll
method is not supported by this Collection.
ClassCastException
- if the types of one or more elements in this
set are incompatible with the specified collection
(optional).
NullPointerException
- if this set contains a null element and
the specified collection does not support null elements
(optional).
NullPointerException
- if the specified collection is
null.remove(Object)
public void clear()
clear
in interface Collection
UnsupportedOperationException
- if the clear method
is not supported by this set.public boolean equals(Object o)
equals
in interface Collection
equals
in class Object
o
- Object to be compared for equality with this set.
Object.hashCode()
,
Hashtable
public int hashCode()
s1.equals(s2)
implies that
s1.hashCode()==s2.hashCode()
for any two sets
s1
and s2
, as required by the general
contract of the Object.hashCode method.
hashCode
in interface Collection
hashCode
in class Object
Object.hashCode()
,
Object.equals(Object)
,
equals(Object)