| public class java.util Vector<E>
|
Java SE 6 |
Vector class implements a growable array of
objects. Like an array, it contains components that can be
accessed using an integer index. However, the size of a
Vector can grow or shrink as needed to accommodate
adding and removing items after the Vector has been created.
Each vector tries to optimize storage management by maintaining a
capacity and a capacityIncrement. The
capacity is always at least as large as the vector
size; it is usually larger because as components are added to the
vector, the vector's storage increases in chunks the size of
capacityIncrement. An application can increase the
capacity of a vector before inserting a large number of
components; this reduces the amount of incremental reallocation.
The Iterators returned by Vector's iterator and listIterator methods are fail-fast: if the Vector is structurally modified at any time after the Iterator is created, in any way except through the Iterator's own remove or add methods, the Iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the Iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future. The Enumerations returned by Vector's elements method are not fail-fast.
Note that the fail-fast behavior of an iterator cannot be guaranteed
as it is, generally speaking, impossible to make any hard guarantees in the
presence of unsynchronized concurrent modification. Fail-fast iterators
throw ConcurrentModificationException on a best-effort basis.
Therefore, it would be wrong to write a program that depended on this
exception for its correctness: the fail-fast behavior of iterators
should be used only to detect bugs.
As of the Java 2 platform v1.2, this class was retrofitted to
implement the List interface, making it a member of the
Java
Collections Framework. Unlike the new collection
implementations, Vector is synchronized.
| version | 1.106, 06/16/06 |
| since | JDK1.0 |
| See also | java.util.Collection, java.util.List, java.util.ArrayList, java.util.LinkedList |
| Fields | |||
|---|---|---|---|
| protected Object[] | elementData Details
The array buffer into which the components of the vector are
stored. The capacity of the vector is the length of this array buffer,
and is at least large enough to contain all the vector's elements.
Any array elements following the last element in the Vector are null.
| ||
| protected int | elementCount Details
The number of valid components in this Vector object.
Components elementData[0] through
elementData[elementCount-1] are the actual items.
| ||
| protected int | capacityIncrement Details
The amount by which the capacity of the vector is automatically
incremented when its size becomes greater than its capacity. If
the capacity increment is less than or equal to zero, the capacity
of the vector is doubled each time it needs to grow.
| ||
| Constructors | |||||||
|---|---|---|---|---|---|---|---|
| public | Vector(int initialCapacity, int capacityIncrement) Details
Constructs an empty vector with the specified initial capacity and
capacity increment.
| ||||||
| public | Vector(int initialCapacity) Details
Constructs an empty vector with the specified initial capacity and
with its capacity increment equal to zero.
| ||||||
| public | Vector() Constructs an empty vector so that its internal data array has size 10 and its standard capacity increment is
zero.
| ||||||
| public | Vector(Collection c) Details
Constructs a vector containing the elements of the specified
collection, in the order they are returned by the collection's
iterator.
| ||||||
| Methods | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| public boolean | add(Object e) Details
Appends the specified element to the end of this Vector.
| ||||||||||||
| public void | add(int index, Object element) Details
Inserts the specified element at the specified position in this Vector.
Shifts the element currently at that position (if any) and any
subsequent elements to the right (adds one to their indices).
| ||||||||||||
| public boolean | addAll(Collection c) Details
Appends all of the elements in the specified Collection to the end of
this Vector, in the order that they are returned by the specified
Collection's Iterator. 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
specified Collection is this Vector, and this Vector is nonempty.)
| ||||||||||||
| public boolean | addAll(int index, Collection c) Details
Inserts all of the elements in the specified Collection into this
Vector at the specified position. Shifts the element currently at
that position (if any) and any subsequent elements to the right
(increases their indices). The new elements will appear in the Vector
in the order that they are returned by the specified Collection's
iterator.
| ||||||||||||
| public void | addElement(Object obj) Details
Adds the specified component to the end of this vector,
increasing its size by one. The capacity of this vector is
increased if its size becomes greater than its capacity.
This method is identical in functionality to the
| ||||||||||||
| public int | capacity() Details
Returns the current capacity of this vector.
| ||||||||||||
| public void | clear() Details
Removes all of the elements from this Vector. The Vector will
be empty after this call returns (unless it throws an exception).
| ||||||||||||
| public Object | clone() Details
Returns a clone of this vector. The copy will contain a
reference to a clone of the internal data array, not a reference
to the original internal data array of this Vector object.
| ||||||||||||
| public boolean | contains(Object o) Details
Returns true if this vector contains the specified element.
More formally, returns true if and only if this vector
contains at least one element e such that
(o==null ? e==null : o.equals(e)).
| ||||||||||||
| public boolean | containsAll(Collection c) Details
Returns true if this Vector contains all of the elements in the
specified Collection.
| ||||||||||||
| public void | copyInto(Object[] anArray) Details
Copies the components of this vector into the specified array.
The item at index k in this vector is copied into
component k of anArray.
| ||||||||||||
| public Object | elementAt(int index) Details
Returns the component at the specified index.
This method is identical in functionality to the
| ||||||||||||
| public Enumeration | elements() Details
Returns an enumeration of the components of this vector. The
returned Enumeration object will generate all items in
this vector. The first item generated is the item at index 0,
then the item at index 1, and so on.
| ||||||||||||
| public void | ensureCapacity(int minCapacity) Details
Increases the capacity of this vector, if necessary, to ensure
that it can hold at least the number of components specified by
the minimum capacity argument.
If the current capacity of this vector is less than
| ||||||||||||
| public boolean | equals(Object o) Details
Compares the specified Object with this Vector for equality. Returns
true if and only if the specified Object is also a List, both Lists
have the same size, and all corresponding pairs of elements in the two
Lists are equal. (Two elements e1 and
e2 are equal if (e1==null ? e2==null :
e1.equals(e2)).) In other words, two Lists are defined to be
equal if they contain the same elements in the same order.
| ||||||||||||
| public Object | firstElement() Details
Returns the first component (the item at index 0) of
this vector.
| ||||||||||||
| public Object | get(int index) Details
Returns the element at the specified position in this Vector.
| ||||||||||||
| public int | hashCode() Returns the hash code value for this Vector. | ||||||||||||
| public int | indexOf(Object o) Details
Returns the index of the first occurrence of the specified element
in this vector, or -1 if this vector does not contain the element.
More formally, returns the lowest index i such that
(o==null ? get(i)==null : o.equals(get(i))),
or -1 if there is no such index.
| ||||||||||||
| public int | indexOf(Object o, int index) Details
Returns the index of the first occurrence of the specified element in
this vector, searching forwards from index, or returns -1 if
the element is not found.
More formally, returns the lowest index i such that
(i >= index && (o==null ? get(i)==null : o.equals(get(i)))),
or -1 if there is no such index.
| ||||||||||||
| public void | insertElementAt(Object obj, int index) Details
Inserts the specified object as a component in this vector at the
specified index. Each component in this vector with
an index greater or equal to the specified index is
shifted upward to have an index one greater than the value it had
previously.
The index must be a value greater than or equal to This method is identical in functionality to the
| ||||||||||||
| public Object | lastElement() Details
Returns the last component of the vector.
| ||||||||||||
| public int | lastIndexOf(Object o) Details
Returns the index of the last occurrence of the specified element
in this vector, or -1 if this vector does not contain the element.
More formally, returns the highest index i such that
(o==null ? get(i)==null : o.equals(get(i))),
or -1 if there is no such index.
| ||||||||||||
| public int | lastIndexOf(Object o, int index) Details
Returns the index of the last occurrence of the specified element in
this vector, searching backwards from index, or returns -1 if
the element is not found.
More formally, returns the highest index i such that
(i <= index && (o==null ? get(i)==null : o.equals(get(i)))),
or -1 if there is no such index.
| ||||||||||||
| public boolean | remove(Object o) Details
Removes the first occurrence of the specified element in this Vector
If the Vector does not contain the element, it is unchanged. More
formally, removes the element with the lowest index i such that
(o==null ? get(i)==null : o.equals(get(i))) (if such
an element exists).
| ||||||||||||
| public Object | remove(int index) Details
Removes the element at the specified position in this Vector.
Shifts any subsequent elements to the left (subtracts one from their
indices). Returns the element that was removed from the Vector.
| ||||||||||||
| public boolean | removeAll(Collection c) Details
Removes from this Vector all of its elements that are contained in the
specified Collection.
| ||||||||||||
| public void | removeAllElements() Removes all components from this vector and sets its size to zero. This method is identical in functionality to the | ||||||||||||
| public boolean | removeElement(Object obj) Details
Removes the first (lowest-indexed) occurrence of the argument
from this vector. If the object is found in this vector, each
component in the vector with an index greater or equal to the
object's index is shifted downward to have an index one smaller
than the value it had previously.
This method is identical in functionality to the
| ||||||||||||
| public void | removeElementAt(int index) Details
Deletes the component at the specified index. Each component in
this vector with an index greater or equal to the specified
index is shifted downward to have an index one
smaller than the value it had previously. The size of this vector
is decreased by 1.
The index must be a value greater than or equal to This method is identical in functionality to the
| ||||||||||||
| protected void | removeRange(int fromIndex, int toIndex) Details
Removes from this List all of the elements whose index is between
fromIndex, inclusive and toIndex, exclusive. Shifts any succeeding
elements to the left (reduces their index).
This call shortens the ArrayList by (toIndex - fromIndex) elements. (If
toIndex==fromIndex, this operation has no effect.)
| ||||||||||||
| public boolean | retainAll(Collection c) Details
Retains only the elements in this Vector that are contained in the
specified Collection. In other words, removes from this Vector all
of its elements that are not contained in the specified Collection.
| ||||||||||||
| public Object | set(int index, Object element) Details
Replaces the element at the specified position in this Vector with the
specified element.
| ||||||||||||
| public int | size() Details
Returns the number of components in this vector.
| ||||||||||||
| public List | subList(int fromIndex, int toIndex) Details
Returns a view of the portion of this List between fromIndex,
inclusive, and toIndex, exclusive. (If fromIndex and toIndex are
equal, the returned List is empty.) The returned List is backed by this
List, so changes in the returned List are reflected in this List, and
vice-versa. The returned List supports all of the optional List
operations supported by this List.
This method eliminates the need for explicit range operations (of the sort that commonly exist for arrays). Any operation that expects a List can be used as a range operation by operating on a subList view instead of a whole List. For example, the following idiom removes a range of elements from a List: list.subList(from, to).clear();Similar idioms may be constructed for indexOf and lastIndexOf, and all of the algorithms in the Collections class can be applied to a subList. The semantics of the List returned by this method become undefined if the backing list (i.e., this List) is structurally modified in any way other than via the returned List. (Structural modifications are those that change the size of the List, or otherwise perturb it in such a fashion that iterations in progress may yield incorrect results.)
| ||||||||||||
| public Object[] | toArray() Details
Returns an array containing all of the elements in this Vector
in the correct order.
| ||||||||||||
| public Object[]<T> | toArray(Object[] a) Details
Returns an array containing all of the elements in this Vector in the
correct order; the runtime type of the returned array is that of the
specified array. If the Vector 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 Vector.
If the Vector fits in the specified array with room to spare (i.e., the array has more elements than the Vector), the element in the array immediately following the end of the Vector is set to null. (This is useful in determining the length of the Vector only if the caller knows that the Vector does not contain any null elements.)
| ||||||||||||
| public String | toString() Returns a string representation of this Vector, containing the String representation of each element. | ||||||||||||
| public void | trimToSize() Trims the capacity of this vector to be the vector's current size. If the capacity of this vector is larger than its current size, then the capacity is changed to equal the size by replacing its internal data array, kept in the field elementData,
with a smaller one. An application can use this operation to
minimize the storage of a vector.
| ||||||||||||
| Properties | |||||||
|---|---|---|---|---|---|---|---|
| public void | setElementAt(Object obj, int index) Details
Sets the component at the specified index of this
vector to be the specified object. The previous component at that
position is discarded.
The index must be a value greater than or equal to This method is identical in functionality to the
| ||||||
| public boolean | isEmpty() Details
Tests if this vector has no components.
| ||||||
| public void | setSize(int newSize) Details
Sets the size of this vector. If the new size is greater than the
current size, new null items are added to the end of
the vector. If the new size is less than the current size, all
components at index newSize and greater are discarded.
| ||||||
| About DocWeb · Bundles · Export · Export All | Top 10 · Statistics · Login |
| About Sun · Contact · Privacy · Terms of Use · Trademarks | Java SE 6 · Copyright © 1994-2009 Sun Microsystems, Inc.All rights reserved. Use is subject to license terms |
![]() |
![]() |
|