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public class java.util.Vector
(source file: Vector.java)
java.lang.Object

+java.util.AbstractCollection<A>

+java.util.AbstractList<A>

+java.util.Vector
The pure class interface.
public class Vector
extends AbstractList
implements List<A>, Cloneable, java.io.Serializable

The
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.
As of JDK1.2, this class has been retrofitted to implement List,
so that it becomes a part of Java's collection framework. Unlike
the new collection implementations, Vector is synchronized.
The Iterators returned by Vector's iterator and listIterator
methods are failfast: 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, nondeterministic behavior at an undetermined time in the future.
The Enumerations returned by Vector's elements method are not
failfast.
 See also:
 Collection, List, ArrayList, LinkedList
 Vector()

Constructs an empty vector so that its internal data array
has size 10 and its
 Vector(Collection<A>)

Constructs a vector containing the elements of the specified
collection, in the order they
 Vector(int)

Constructs an empty vector with the specified initial capacity and
with its capacity
 Vector(int, int)

Constructs an empty vector with the specified initial capacity and
capacity increment
 capacityIncrement

The amount by which the capacity of the vector is automatically
incremented when its size
 elementCount

The number of valid components in this Vector object
 elementData

The array buffer into which the components of the vector are
stored
 add(int, Object)

Inserts the specified element at the specified position in this Vector.
Shifts the element
 addAll(int, Collection<A>)

Inserts all of the elements in in the specified Collection into this
Vector at the
 addAll(Collection<A>)

Appends all of the elements in the specified Collection to the end of
this this Vector, in
 addElement(Object)

Adds the specified component to the end of this vector,
increasing its size by one
 capacity()

Returns the current capacity of this vector.
 clear()

Removes all of the elements from this Vector
 clone()

Returns a clone of this vector
 contains(Object)

Tests if the specified object is a component in this vector.
 copyInto(Object[])

Copies the components of this vector into the specified array
 elementAt(int)

Returns the component at the specified index.
 elements()

Returns an enumeration of the components of this vector
 ensureCapacity(int)

Increases the capacity of this vector, if necessary, to ensure
that it can hold at least
 firstElement()

Returns the first component (the item at index 0) of
this vector.
 get(int)

Returns the element at the specified position in this Vector.
 indexOf(Object, int)

Searches for the first occurence of the given argument, beginning
the search at
 indexOf(Object)

Searches for the first occurence of the given argument, testing
for equality using the
 insertElementAt(Object, int)

Inserts the specified object as a component in this vector at the
specified
 isEmpty()

Tests if this vector has no components.
 lastElement()

Returns the last component of the vector.
 lastIndexOf(Object, int)

Searches backwards for the specified object, starting from the
specified index, and
 lastIndexOf(Object)

Returns the index of the last occurrence of the specified object in
this vector.
 remove(int)

Removes the element at the specified position in this Vector.
shifts any subsequent
 removeAllElements()

Removes all components from this vector and sets its size to zero.
 removeElement(Object)

Removes the first (lowestindexed) occurrence of the argument
from this vector
 removeElementAt(int)

Deletes the component at the specified index
 removeRange(int, int)

Removes from this Vector all of the elements whose index is between
fromIndex, inclusive
 set(int, Object)

Replaces the element at the specified position in this Vector with the
specified element.
 setElementAt(Object, int)

Sets the component at the specified
index
of this
vector to be the specified
 setSize(int)

Sets the size of this vector
 size()

Returns the number of components in this vector.
 toArray()

Returns an array containing all of the elements in this Vector
in the correct order.
 trimToSize()

Trims the capacity of this vector to be the vector's current
size
Vector
public Vector(int initialCapacity,
int capacityIncrement);

Constructs an empty vector with the specified initial capacity and
capacity increment.
 Parameters:
 initialCapacity  the initial capacity of the vector.
 capacityIncrement  the amount by which the capacity is
increased when the vector overflows.
 Throws:
 IllegalArgumentException if the specified initial capacity
is negative

Vector
public Vector(int initialCapacity);

Constructs an empty vector with the specified initial capacity and
with its capacity increment equal to zero.
 Parameters:
 initialCapacity  the initial capacity of the vector.
 Throws:
 IllegalArgumentException if the specified initial capacity
is negative

Vector
public Vector();

Constructs an empty vector so that its internal data array
has size 10 and its standard capacity increment is
zero.
Vector
public Vector(Collection<A> c);

Constructs a vector containing the elements of the specified
collection, in the order they are returned by the collection's
iterator.
elementData
protected Object[] elementData;

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.
elementCount
protected int elementCount;

The number of valid components in this Vector object.
Components elementData[0] through
elementData[elementCount1] are the actual items.
capacityIncrement
protected int capacityIncrement;

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
0
, the capacity of the
vector is doubled each time it needs to grow.
copyInto
public synchronized void copyInto(Object[] anArray);

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. The array must be big enough to hold
all the objects in this vector, else an
IndexOutOfBoundsException is thrown.
 Parameters:
 anArray  the array into which the components get copied.
trimToSize
public synchronized void trimToSize();

Trims the capacity of this vector to be the vector's current
size. If the capacity of this cector 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.
ensureCapacity
public synchronized void ensureCapacity(int minCapacity);

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 minCapacity, then its capacity is
increased by replacing its internal data array, kept in the field
elementData, with a larger one. The size of the new data
array will be the old size plus capacityIncrement, unless
the value of capacityIncrement is nonpositive, in which
case the new capacity will be twice the old capacity; but if
this new size is still smaller than minCapacity, then the
new capacity will be minCapacity.
 Parameters:
 minCapacity  the desired minimum capacity.
setSize
public synchronized void setSize(int newSize);

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.
 Parameters:
 newSize  the new size of this vector.
capacity
public int capacity();

Returns the current capacity of this vector.
 Returns:
 the current capacity (the length of its internal
data arary, kept in the field elementData
of this vector.
size
public int size();

Returns the number of components in this vector.
 Returns:
 the number of components in this vector.
 Overrides:
 size in class AbstractCollection
isEmpty
public boolean isEmpty();

Tests if this vector has no components.
 Returns:
true
if and only if this vector has
no components, that is, its size is zero;
false
otherwise.
 Overrides:
 isEmpty in class AbstractCollection
elements
public synchronized Enumeration elements();

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.
 Returns:
 an enumeration of the components of this vector.
 See also:
 Enumeration, Iterator
contains
public boolean contains(Object elem);

Tests if the specified object is a component in this vector.
 Parameters:
 elem  an object.
 Returns:
true
if and only if the specified object
is the same as a component in this vector, as determined by the
equals method; false
otherwise.
indexOf
public int indexOf(Object elem);

Searches for the first occurence of the given argument, testing
for equality using the
equals
method.
 Parameters:
 elem  an object.
 Returns:
 the index of the first occurrence of the argument in this
vector, that is, the smallest value k such that
elem.equals(elementData[k]) is true;
returns
1
if the object is not found.
 See also:
 equals(Object)
indexOf
public synchronized int indexOf(Object elem,
int index);

Searches for the first occurence of the given argument, beginning
the search at
index
, and testing for equality using
the equals
method.
 Parameters:
 elem  an object.
 index  the index to start searching from.
 Returns:
 the index of the first occurrence of the object argument in
this vector at position
index
or later in the
vector, that is, the smallest value k such that
elem.equals(elementData[k]) && (k >= index) is
true; returns 1
if the object is not
found.
 See also:
 equals(Object)
lastIndexOf
public int lastIndexOf(Object elem);

Returns the index of the last occurrence of the specified object in
this vector.
 Parameters:
 elem  the desired component.
 Returns:
 the index of the last occurrence of the specified object in
this vector, that is, the largest value k such that
elem.equals(elementData[k]) is true;
returns
1
if the object is not found.
lastIndexOf
public synchronized int lastIndexOf(Object elem,
int index);

Searches backwards for the specified object, starting from the
specified index, and returns an index to it.
 Parameters:
 elem  the desired component.
 index  the index to start searching from.
 Returns:
 the index of the last occurrence of the specified object in this
vector at position less than
index
in the
vector, that is, the largest value k such that
elem.equals(elementData[k]) && (k <= index) is
true; 1
if the object is not found.
elementAt
public synchronized Object elementAt(int index);

Returns the component at the specified index.
This method is identical in functionality to the get method
(which is part of the List interface).
 Parameters:
 index  an index into this vector.
 Returns:
 the component at the specified index.
 Throws:
 ArrayIndexOutOfBoundsException  if the index
is negative or not less than the current size of this
Vector object.
given.

 See also:
 get(int), List
firstElement
public synchronized Object firstElement();

Returns the first component (the item at index 0) of
this vector.
 Returns:
 the first component of this vector.
 Throws:
 NoSuchElementException  if this vector has no components.

lastElement
public synchronized Object lastElement();

Returns the last component of the vector.
 Returns:
 the last component of the vector, i.e., the component at index
size()  1
.
 Throws:
 NoSuchElementException  if this vector is empty.

setElementAt
public synchronized void setElementAt(Object obj,
int index);

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 0
and less than the current size of the vector.
This method is identical in functionality to the set method
(which is part of the List interface). Note that the set method reverses
the order of the parameters, to more closely match array usage. Note
also that the set method returns the old value that was stored at the
specified position.
 Parameters:
 obj  what the component is to be set to.
 index  the specified index.
 Throws:
 ArrayIndexOutOfBoundsException  if the index was invalid.

 See also:
 size(), List, set
removeElementAt
public synchronized void removeElementAt(int index);

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 0
and less than the current size of the vector.
This method is identical in functionality to the remove method
(which is part of the List interface). Note that the remove method
returns the old value that was stored at the specified position.
 Parameters:
 index  the index of the object to remove.
 Throws:
 ArrayIndexOutOfBoundsException  if the index was invalid.

 See also:
 size(), remove(int), List
insertElementAt
public synchronized void insertElementAt(Object obj,
int index);

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 0
and less than or equal to the current size of the vector.
This method is identical in functionality to the add(Object, int) method
(which is part of the List interface). Note that the add method reverses
the order of the parameters, to more closely match array usage.
 Parameters:
 obj  the component to insert.
 index  where to insert the new component.
 Throws:
 ArrayIndexOutOfBoundsException  if the index was invalid.

 See also:
 size(), add(Object, int), List
addElement
public synchronized void addElement(Object obj);

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 add(Object) method
(which is part of the List interface).
 Parameters:
 obj  the component to be added.
 See also:
 add(Object), List
removeElement
public synchronized boolean removeElement(Object obj);

Removes the first (lowestindexed) 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 remove(Object)
method (which is part of the List interface).
 Parameters:
 obj  the component to be removed.
 Returns:
true
if the argument was a component of this
vector; false
otherwise.
 See also:
 remove(Object), List
removeAllElements
public synchronized void removeAllElements();

Removes all components from this vector and sets its size to zero.
This method is identical in functionality to the clear method
(which is part of the List interface).
 See also:
 clear, List
clone
public synchronized Object clone();

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.
 Returns:
 a clone of this vector.
 Overrides:
 clone in class Object
toArray
public synchronized Object[] toArray();

Returns an array containing all of the elements in this Vector
in the correct order.
 Overrides:
 toArray in class AbstractCollection
get
public synchronized Object get(int index);

Returns the element at the specified position in this Vector.
 Parameters:
 index  index of element to return.
 Throws:
 ArrayIndexOutOfBoundsException index is out of range (index
< 0  index >= size()).

 Overrides:
 get in class AbstractList
set
public synchronized Object set(int index,
Object element);

Replaces the element at the specified position in this Vector with the
specified element.
 Parameters:
 index  index of element to replace.
 element  element to be stored at the specified position.
 Returns:
 the element previously at the specified position.
 Throws:
 ArrayIndexOutOfBoundsException index out of range
(index < 0  index >= size()).
 IllegalArgumentException fromIndex > toIndex.

add
public synchronized void add(int index,
Object element);

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).
 Parameters:
 index  index at which the specified element is to be inserted.
 element  element to be inserted.
 Throws:
 ArrayIndexOutOfBoundsException index is out of range
(index < 0  index > size()).

remove
public synchronized Object remove(int index);

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.
 Parameters:
 index  the index of the element to removed.
 Throws:
 ArrayIndexOutOfBoundsException index out of range (index
< 0  index >= size()).

 Overrides:
 remove in class AbstractList
clear
public synchronized void clear();

Removes all of the elements from this Vector. The Vector will
be empty after this call returns (unless it throws an exception).
 Throws:
 UnsupportedOperationException clear is not supported
by this Set.

 Overrides:
 clear in class AbstractCollection
addAll
public synchronized boolean addAll(Collection<A> c);

Appends all of the elements in the specified Collection to the end of
this 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 the
specified Collection is this Vector, and this Vector is nonempty.)
 Parameters:
 index  index at which to insert first element
from the specified collection.
 c  elements to be inserted into this Vector.
 Throws:
 ArrayIndexOutOfBoundsException index out of range (index
< 0  index > size()).

removeRange
public synchronized void removeRange(int fromIndex,
int toIndex);

Removes from this Vector 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 Vector by (toIndex  fromIndex) elements. (If
toIndex==fromIndex, this operation has no effect.)
 Parameters:
 fromIndex  index of first element to be removed.
 fromIndex  index after last element to be removed.
 Throws:
 ArrayIndexOutOfBoundsException fromIndex or toIndex out of
range (fromIndex < 0  fromIndex >= size()  toIndex
> size()  toIndex < fromIndex).

 Overrides:
 removeRange in class AbstractList
addAll
public synchronized boolean addAll(int index,
Collection<A> c);

Inserts all of the elements in 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.
 Parameters:
 index  index at which to insert first element
from the specified collection.
 c  elements to be inserted into this Vector.
 Throws:
 ArrayIndexOutOfBoundsException index out of range (index
< 0  index > size()).

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[package java.util]
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