Class java.util.Collections.UnmodifiableCollection
java.lang.Object
|
+--java.util.Collections.UnmodifiableCollection
- Subclasses:
- Collections.UnmodifiableList, Collections.UnmodifiableSet
- static class Collections.UnmodifiableCollection
- extends java.lang.Object
- implements Collection, java.io.Serializable
- See Also:
- Serialized Form
Methods inherited from class java.lang.Object |
, clone, equals, finalize, getClass, hashCode, notifyAll, notify, toString, wait, wait, wait |
Collections.UnmodifiableCollection
Collections.UnmodifiableCollection(Collection c)
size
public int size()
- Description copied from interface:
Returns the number of elements in this Collection.
- Specified by:
- size in interface Collection
isEmpty
public boolean isEmpty()
- Description copied from interface:
Returns true if this Collection contains no elements.
- Specified by:
- isEmpty in interface Collection
contains
public boolean contains(java.lang.Object o)
- Description copied from interface:
Returns true if this Collection contains the specified element. More
formally, returns true if and only if this Collection contains at least
one element e
such that (o==null ? e==null :
o.equals(e))
.
- Specified by:
- contains in interface Collection
toArray
public java.lang.Object[] toArray()
- Description copied from interface:
Returns an array containing all of the elements in this Collection. If
the Collection makes any guarantees as to what order its elements are
returned by its Iterator, this method must return the elements in the
same order. The returned array will be "safe" in that no references to
it are maintained by the Collection. (In other words, this method must
allocate a new array even if the Collection is backed by an Array).
The caller is thus free to modify the returned array.
This method acts as bridge between array-based and Collection-based
APIs.
- Specified by:
- toArray in interface Collection
toArray
public java.lang.Object[] toArray(java.lang.Object[] a)
- Description copied from interface:
Returns an array containing all of the elements in this Collection,
whose runtime type is that of the specified array. If the Collection
fits in the specified array, it is returned therein. Otherwise,
a new array is allocated with the runtime type of the specified array
and the size of this Collection.
If the Collection fits in the specified array with room to spare
(i.e., the array has more elements than the Collection),
the element in the array immediately following the end of the
collection is set to null. This is useful in determining the length
of the Collection only if the caller knows that the Collection
does not contain any null elements.)
If this Collection makes any guarantees as to what order its elements
are returned by its Iterator, this method must return the elements in
the same order.
Like toArray()
, this method acts as bridge between
array-based and Collection-based APIs. Further, this method allows
precise control over the runtime type of the output array, and
may, under certain circumstances, be used to save allocation costs
Suppose l is a List known to contain only strings. The following code
can be used to dump the list into a newly allocated array of String:
String[] x = (String[]) v.toArray(new String[0]);
Note that toArray(new Object[0])
is identical in
function to toArray()
.
- Specified by:
- toArray in interface Collection
iterator
public Iterator iterator()
- Description copied from interface:
Returns an Iterator over the elements in this Collection. There are
no guarantees concerning the order in which the elements are returned
(unless this Collection is an instance of some class that provides a
guarantee).
- Specified by:
- iterator in interface Collection
add
public boolean add(java.lang.Object o)
- Description copied from interface:
Ensures that this Collection contains the specified element (optional
operation). Returns true if the Collection changed as a result of the
call. (Returns false if this Collection does not permit duplicates and
already contains the specified element.) Collections that support this
operation may place limitations on what elements may be added to the
Collection. In particular, some Collections will refuse to add null
elements, and others will impose restrictions on the type of elements
that may be added. Collection classes should clearly specify in their
documentation any restrictions on what elements may be added.
- Specified by:
- add in interface Collection
remove
public boolean remove(java.lang.Object o)
- Description copied from interface:
Removes a single instance of the specified element from this Collection,
if it is present (optional operation). More formally, removes an
element e
such that (o==null ? e==null :
o.equals(e))
, if the Collection contains one or more such
elements. Returns true if the Collection contained the specified
element (or equivalently, if the Collection changed as a result of the
call).
- Specified by:
- remove in interface Collection
containsAll
public boolean containsAll(Collection coll)
- Description copied from interface:
Returns true if this Collection contains all of the elements in the
specified Collection.
- Specified by:
- containsAll in interface Collection
addAll
public boolean addAll(Collection coll)
- Description copied from interface:
Adds all of the elements in the specified Collection to this Collection
(optional operation). The behavior of this operation is undefined if
the specified Collection is modified while the operation is in progress.
(This implies that the behavior of this call is undefined if the the
specified Collection is this Collection, and this Collection is
nonempty.)
- Specified by:
- addAll in interface Collection
removeAll
public boolean removeAll(Collection coll)
- Description copied from interface:
Removes from this Collection all of its elements that are contained in
the specified Collection (optional operation). After this call returns,
this Collection will contains no elements in common with the specified
Collection.
- Specified by:
- removeAll in interface Collection
retainAll
public boolean retainAll(Collection coll)
- Description copied from interface:
Retains only the elements in this Collection that are contained in the
specified Collection (optional operation). In other words, removes from
this Collection all of its elements that are not contained in the
specified Collection.
- Specified by:
- retainAll in interface Collection
clear
public void clear()
- Description copied from interface:
Removes all of the elements from this Collection (optional operation).
The Collection will be empty after this call returns (unless it throws
an exception).
- Specified by:
- clear in interface Collection