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| java.lang.Object
 java.util.AbstractCollection
| AbstractCollection | | abstract public class AbstractCollection implements Collection<E>(Code) | | This class provides a skeletal implementation of the Collection
interface, to minimize the effort required to implement this interface.
To implement an unmodifiable collection, the programmer needs only to
extend this class and provide implementations for the iterator and
size methods. (The iterator returned by the iterator
method must implement hasNext and next.)
To implement a modifiable collection, the programmer must additionally
override this class's add method (which otherwise throws an
UnsupportedOperationException), and the iterator returned by the
iterator method must additionally implement its remove
method.
The programmer should generally provide a void (no argument) and
Collection constructor, as per the recommendation in the
Collection interface specification.
The documentation for each non-abstract method in this class describes its
implementation in detail. Each of these methods may be overridden if
the collection being implemented admits a more efficient implementation.
This class is a member of the
Java Collections Framework.
author:
Josh Bloch
author:
Neal Gafter
version:
1.44, 05/05/07
See Also: Collection
since:
1.2 |
| Method Summary | |
| public boolean | add(E e)
This implementation always throws an
UnsupportedOperationException. | | public boolean | addAll(Collection<? extends E> c)
This implementation iterates over the specified collection, and adds
each object returned by the iterator to this collection, in turn. | | public void | clear()
This implementation iterates over this collection, removing each
element using the Iterator.remove operation. | | public boolean | contains(Object o)
This implementation iterates over the elements in the collection,
checking each element in turn for equality with the specified element. | | public boolean | containsAll(Collection c)
This implementation iterates over the specified collection,
checking each element returned by the iterator in turn to see
if it's contained in this collection. | | public boolean | isEmpty()
This implementation returns size() == 0. | | abstract public Iterator<E> | iterator()
Returns an iterator over the elements contained in this collection. | | public boolean | remove(Object o)
This implementation iterates over the collection looking for the
specified element. | | public boolean | removeAll(Collection c)
This implementation iterates over this collection, checking each
element returned by the iterator in turn to see if it's contained
in the specified collection. | | public boolean | retainAll(Collection c)
This implementation iterates over this collection, checking each
element returned by the iterator in turn to see if it's contained
in the specified collection. | | abstract public int | size()
| | public Object[] | toArray()
This implementation returns an array containing all the elements
returned by this collection's iterator, in the same order, stored in
consecutive elements of the array, starting with index
0 .
The length of the returned array is equal to the number of elements
returned by the iterator, even if the size of this collection changes
during iteration, as might happen if the collection permits
concurrent modification during iteration. | | public T[] | toArray(T[] a)
This implementation returns an array containing all the elements
returned by this collection's iterator in the same order, stored in
consecutive elements of the array, starting with index
0 .
If the number of elements returned by the iterator is too large to
fit into the specified array, then the elements are returned in a
newly allocated array with length equal to the number of elements
returned by the iterator, even if the size of this collection
changes during iteration, as might happen if the collection permits
concurrent modification during iteration. | | public String | toString()
Returns a string representation of this collection. |
| AbstractCollection | | protected AbstractCollection()(Code) | | Sole constructor. (For invocation by subclass constructors, typically
implicit.)
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| clear | | public void clear()(Code) | | This implementation iterates over this collection, removing each
element using the Iterator.remove operation. Most
implementations will probably choose to override this method for
efficiency.
Note that this implementation will throw an
UnsupportedOperationException if the iterator returned by this
collection's iterator method does not implement the
remove method and this collection is non-empty.
throws:
UnsupportedOperationException - |
| isEmpty | | public boolean isEmpty()(Code) | | This implementation returns size() == 0.
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| iterator | | abstract public Iterator<E> iterator()(Code) | | Returns an iterator over the elements contained in this collection.
an iterator over the elements contained in this collection |
| remove | | public boolean remove(Object o)(Code) | | This implementation iterates over the collection looking for the
specified element. If it finds the element, it removes the element
from the collection using the iterator's remove method.
Note that this implementation throws an
UnsupportedOperationException if the iterator returned by this
collection's iterator method does not implement the remove
method and this collection contains the specified object.
throws:
UnsupportedOperationException -
throws:
ClassCastException -
throws:
NullPointerException - |
| size | | abstract public int size()(Code) | | |
| toArray | | public Object[] toArray()(Code) | | This implementation returns an array containing all the elements
returned by this collection's iterator, in the same order, stored in
consecutive elements of the array, starting with index
0 .
The length of the returned array is equal to the number of elements
returned by the iterator, even if the size of this collection changes
during iteration, as might happen if the collection permits
concurrent modification during iteration. The
size method is
called only as an optimization hint; the correct result is returned
even if the iterator returns a different number of elements.
This method is equivalent to:
List list = new ArrayList(size()); for (E e : this) list.add(e); return list.toArray();
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| toArray | | public T[] toArray(T[] a)(Code) | | This implementation returns an array containing all the elements
returned by this collection's iterator in the same order, stored in
consecutive elements of the array, starting with index
0 .
If the number of elements returned by the iterator is too large to
fit into the specified array, then the elements are returned in a
newly allocated array with length equal to the number of elements
returned by the iterator, even if the size of this collection
changes during iteration, as might happen if the collection permits
concurrent modification during iteration. The
size method is
called only as an optimization hint; the correct result is returned
even if the iterator returns a different number of elements.
This method is equivalent to:
List list = new ArrayList(size()); for (E e : this) list.add(e); return list.toArray(a);
throws:
ArrayStoreException -
throws:
NullPointerException - |
| toString | | public String toString()(Code) | | Returns a string representation of this collection. The string
representation consists of a list of the collection's elements in the
order they are returned by its iterator, enclosed in square brackets
("[]"). Adjacent elements are separated by the characters
", " (comma and space). Elements are converted to strings as
by
String.valueOf(Object) .
a string representation of this collection |
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