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спецификации, руководства, описания, API

java.util.Vector
Vector
, like an array, contains items that can be accessed using an integer
index. However, the size of a Vector
can grow and shrink as needed to accommodate
adding and removing items after the Vector
has been created.
public classVector
implements Cloneable { protected Object[]elementData
; protected intelementCount
; protected intcapacityIncrement
; publicVector
(int initialCapacity, int capacityIncrement); publicVector
(int initialCapacity); publicVector
(); public final StringtoString
(); public Objectclone
(); public final ObjectelementAt
(int index) throwsIndexOutOfBoundsException
; public final voidsetElementAt
(Object obj, int index) throwsIndexOutOfBoundsException
; public final ObjectfirstElement
() throws NoSuchElementException; public final ObjectlastElement
() throws NoSuchElementException; public final voidaddElement
(Object obj); public final voidinsertElementAt
(Object obj, int index) throwsIndexOutOfBoundsException
; public final booleanremoveElement
(Object obj); public final voidremoveElementAt
(int index) throwsIndexOutOfBoundsException
; public final voidremoveAllElements
(); public final booleanisEmpty
(); public final intsize
(); public final voidsetSize
(int newSize); public final intcapacity
(); public final voidensureCapacity
(int minCapacity); public final voidtrimToSize
(); public final voidcopyInto
(Object anArray[]) throwsIndexOutOfBoundsException
; public final Enumerationelements
(); public final booleancontains
(Object elem); public final intindexOf
(Object elem); public final intindexOf
(Object elem, int index) throwsIndexOutOfBoundsException
; public final intlastIndexOf
(Object elem); public final intlastIndexOf
(Object elem, int index) throwsIndexOutOfBoundsException
; }
21.11.1 protected Object[]
elementData
;
Internally, a Vector
keeps its elements in an array that is at least large enough to
contain all the elements.
21.11.2 protected int
elementCount
;
This field holds the number of items currently in this Vector
object. Components
elementData[0]
through elementData[elementCount1]
are the actual items.
21.11.3 protected int
capacityIncrement
;
When the method ensureCapacity
(§21.11.22) must increase the size of the data
array in the field elementData
(by creating a new array), it increases the size by
at least the amount in capacityIncrement
; but if capacityIncrement
is zero,
then it at least doubles the size of the data array.
21.11.4 public
Vector
(int initialCapacity, int capacityIncrement)
This constructor initializes a newly created Vector
so that its internal data array
has size initialCapacity
and its standard capacity increment is the value of
capacityIncrement
. Initially, the Vector
contains no items.
21.11.5 public
Vector
(int initialCapacity)
This constructor initializes a newly created Vector
so that its internal data array
has size initialCapacity
and its standard capacity increment is zero. Initially,
the Vector
contains no items.
21.11.6 public
Vector
()
This constructor initializes a newly created Vector
so that its internal data array
has size 10
and its standard capacity increment is zero. Initially the Vector
contains
no items.
21.11.7 public final String
toString
()
This Vector
is represented in string form as a list of its items, enclosed in ASCII
square brackets and separated by the ASCII characters ",
" (comma and space).
The toString
method is used to convert the items to strings; a null reference is
rendered as the string "null
".
Vector v = new Vector(); v.addElement("Canberra"); v.addElement("Cancun"); v.addElement("Canandaigua"); System.out.println(v.toString());produces the output:
[Canberra, Cancun, Canandaigua]Overrides the
toString
method of Object
(§20.1.2).21.11.8 public Object
clone
()
A copy of this Vector
is constructed and returned. The copy will contains a reference
to a clone of the internal data array, not a reference to the original internal
data array of this Vector
.
Overrides the clone
method of Object
(§20.1.5).
21.11.9 public final Object
elementAt
(int index)
throws IndexOutOfBoundsException
The item of this Vector
with the specified index
is returned.
If the index
is negative or not less than the current size of this Vector
, an IndexOutOfBoundsException
is thrown.
21.11.10 public final void
setElementAt
(Object obj, int index)
throws IndexOutOfBoundsException
The item of this Vector
with the specified index
is replaced with obj
, so that obj
is now the item at the specified index
within this Vector
.
If the index
is negative or not less than the current size of this Vector
, an IndexOutOfBoundsException
is thrown.
21.11.11 public final Object
firstElement
()
throws NoSuchElementException
If this Vector
is empty, a NoSuchElementException
is thrown. Otherwise, the
first item (the item at index 0
) is returned.
21.11.12 public final Object
lastElement
()
throws NoSuchElementException
If this Vector
is empty, a NoSuchElementException
is thrown. Otherwise, the
last item (the item at index size()1
) is returned.
21.11.13 public final void
addElement
(Object obj)
The size of this Vector
is increased by 1
and obj
becomes the new last item.
21.11.14 public final void
insertElementAt
(Object obj, int index)
throws IndexOutOfBoundsException
The size of this Vector
is increased by 1
and obj
becomes the new item at the
specified index
. Any item in this Vector
that was previously at index k
is first
moved to index k+1
if and only if k
is not less than index
.
21.11.15 public final boolean
removeElement
(Object obj)
If this Vector
contains an occurrence of obj
, then the first (lowestindexed) such
occurrence is removed, as if by the method removeElementAt
(§21.11.16), and
true
is returned. If this Vector
contains no occurrence of obj
, this Vector
is not
modified and false
is returned.
21.11.16 public final void
removeElementAt
(int index)
throws IndexOutOfBoundsException
The size of this Vector
is decreased by 1
and the item at the specified index
is
removed from this Vector
. Any item in this Vector
that was previously at index
k
is first moved to index k1
if and only if k
is greater than index
.
21.11.17 public final void
removeAllElements
()
All elements are removed from this Vector
, making it empty.
21.11.18 public final boolean
isEmpty
()
The result is true
if and only if this Vector
is empty, that is, its size is zero.
21.11.19 public final int
size
()
The size of this Vector
(the number of items it currently contains) is returned.
21.11.20 public final void
setSize
(int newSize)
The size of this Vector
is changed to newSize
. If the new size is smaller than the
old size, then items are removed from the end and discarded. If the new size is
larger than the old size, then the new items are set to null
.
21.11.21 public final int
capacity
()
The current capacity of this Vector
(the length of its internal data array, kept in
the field elementData
) is returned.
21.11.22 public final void
ensureCapacity
(int minCapacity)
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
(§21.11.1), with a larger one. The size of the new data array will be the old size
plus capacityIncrement
(§21.11.3), 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
.
21.11.23 public final void
trimToSize
()
If the capacity of this Vector
is larger than its current size
(§21.11.19), then the
capacity is changed to equal the size by replacing its internal data array, kept in
the field elementData
, with a smaller one.
21.11.24 public final void
copyInto
(Object anArray[])
throws IndexOutOfBoundsException
All the items in this Vector
are copied into the array anArray
. The item at index
k
in this Vector
is copied into component k
of anArray
. If the length of anArray
is smaller than the size of this Vector
, an IndexOutOfBoundsException
is
thrown.
21.11.25 public final Enumeration
elements
()
An Enumeration
(§21.1) is returned that 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.
21.11.26 public final boolean
contains
(Object elem)
The result is true
if and only if some item in this Vector
is the same as elem
, as
determined by the equals
method (§20.1.3).
21.11.27 public final int
indexOf
(Object elem)
If an item equal to elem
is in this Vector
, then the index of the first such occurrence
is returned, that is, the smallest value k
such that:
elem.equals(elementData[k])
is true
. If no such item occurs in this Vector
, then 1
is returned.21.11.28 public final int
indexOf
(Object elem, int index)
throws IndexOutOfBoundsException
If an item equal to elem
is in this Vector
at position k
or higher, then the index of
the first such occurrence is returned, that is, the smallest value k
such that:
elem.equals(elementData[k]) && (k >= index)
is true
. If no such item occurs in this Vector
, then 1
is returned.21.11.29 public final int
lastIndexOf
(Object elem)
If an item equal to elem
is in this Vector
, then the index of the last such occurrence
is returned, that is, the largest value k
such that:
elem.equals(elementData[k])
is true
. If no such item occurs in this Vector
, then 1
is returned.21.11.30 public final int
lastIndexOf
(Object elem, int index)
throws IndexOutOfBoundsException
If an item equal to elem
is in this Vector
at position k
or lower, then the index of
the last such occurrence is returned, that is, the largest value k
such that:
elem.equals(elementData[k]) && (k <= index)
is true
. If no such item occurs in this Vector
, then 1
is returned.
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Java Language Specification (HTML generated by Suzette Pelouch on February 24, 1998)
Copyright © 1996 Sun Microsystems, Inc.
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Please send any comments or corrections to doug.kramer@sun.com