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Class java.util.Vector
java.lang.Object

+java.util.Vector
 public class Vector
 extends Object
 implements Cloneable, 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.

capacityIncrement
 The amount by which the capacity of the vector is automatically
incremented when its size becomes greater than its capacity.

elementCount
 The number of valid components in the vector.

elementData
 The array buffer into which the components of the vector are
stored.

Vector()
 Constructs an empty vector.

Vector(int)
 Constructs an empty vector with the specified initial capacity.

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

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.

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 the number of components specified by
the minimum capacity argument.

firstElement()
 Returns the first component of this vector.

indexOf(Object)
 Searches for the first occurence of the given argument, testing
for equality using the
equals
method.

indexOf(Object, int)
 Searches for the first occurence of the given argument, beginning
the search at
index
, and testing for equality using
the equals
method.

insertElementAt(Object, int)
 Inserts the specified object as a component in this vector at the
specified
index
.

isEmpty()
 Tests if this vector has no components.

lastElement()
 Returns the last component of the vector.

lastIndexOf(Object)
 Returns the index of the last occurrence of the specified object in
this vector.

lastIndexOf(Object, int)
 Searches backwards for the specified object, starting from the
specified index, and returns an index to it.

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

removeElement(Object)
 Removes the first occurrence of the argument from this vector.

removeElementAt(int)
 Deletes the component at the specified index.

setElementAt(Object, int)
 Sets the component at the specified
index
of this
vector to be the specified object.

setSize(int)
 Sets the size of this vector.

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

toString()
 Returns a string representation of this vector.

trimToSize()
 Trims the capacity of this vector to be the vector's current
size.
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.
elementCount
protected int elementCount
 The number of valid components in the vector.
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.
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.
Vector
public Vector(int initialCapacity)
 Constructs an empty vector with the specified initial capacity.
 Parameters:
 initialCapacity  the initial capacity of the vector.
Vector
public Vector()
 Constructs an empty vector.
copyInto
public final synchronized void copyInto(Object anArray[])
 Copies the components of this vector into the specified array.
The array must be big enough to hold all the objects in this vector.
 Parameters:
 anArray  the array into which the components get copied.
trimToSize
public final synchronized void trimToSize()
 Trims the capacity of this vector to be the vector's current
size. An application can use this operation to minimize the
storage of a vector.
ensureCapacity
public final 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.
 Parameters:
 minCapacity  the desired minimum capacity.
setSize
public final 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 final int capacity()
 Returns the current capacity of this vector.
 Returns:
 the current capacity of this vector.
size
public final int size()
 Returns the number of components in this vector.
 Returns:
 the number of components in this vector.
isEmpty
public final boolean isEmpty()
 Tests if this vector has no components.
 Returns:

true
if this vector has no components;
false
otherwise.
elements
public final synchronized Enumeration elements()
 Returns an enumeration of the components of this vector.
 Returns:
 an enumeration of the components of this vector.
 See Also:
 Enumeration
contains
public final boolean contains(Object elem)
 Tests if the specified object is a component in this vector.
 Parameters:
 elem  an object.
 Returns:

true
if the specified object is a component in
this vector; false
otherwise.
indexOf
public final 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; returns
1
if the object is not found.
 See Also:
 equals
indexOf
public final 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; returns 1
if the object is not found.
 See Also:
 equals
lastIndexOf
public final 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; returns
1
if the object is not found.
lastIndexOf
public final 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;
1
if the object is not found.
elementAt
public final synchronized Object elementAt(int index)
 Returns the component at the specified index.
 Parameters:
 index  an index into this vector.
 Returns:
 the component at the specified index.
 Throws: ArrayIndexOutOfBoundsException
 if an invalid index was
given.
firstElement
public final synchronized Object firstElement()
 Returns the first component of this vector.
 Returns:
 the first component of this vector.
 Throws: NoSuchElementException
 if this vector has no components.
lastElement
public final 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 final 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.
 Parameters:
 obj  what the component is to be set to.
 index  the specified index.
 Throws: ArrayIndexOutOfBoundsException
 if the index was invalid.
 See Also:
 size
removeElementAt
public final 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 index must be a value greater than or equal to 0
and less than the current size of the vector.
 Parameters:
 index  the index of the object to remove.
 Throws: ArrayIndexOutOfBoundsException
 if the index was invalid.
 See Also:
 size
insertElementAt
public final 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.
 Parameters:
 obj  the component to insert.
 index  where to insert the new component.
 Throws: ArrayIndexOutOfBoundsException
 if the index was invalid.
 See Also:
 size
addElement
public final 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.
 Parameters:
 obj  the component to be added.
removeElement
public final synchronized boolean removeElement(Object obj)
 Removes the first 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.
 Parameters:
 obj  the component to be removed.
 Returns:

true
if the argument was a component of this
vector; false
otherwise.
removeAllElements
public final synchronized void removeAllElements()
 Removes all components from this vector and sets its size to zero.
clone
public synchronized Object clone()
 Returns a clone of this vector.
 Returns:
 a clone of this vector.
 Overrides:
 clone in class Object
toString
public final synchronized String toString()
 Returns a string representation of this vector.
 Returns:
 a string representation of this vector.
 Overrides:
 toString in class Object
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