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JavaTM 2 Platform Std. Ed. v1.3.1 |
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SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Object | +--java.util.AbstractCollection | +--java.util.AbstractList | +--java.util.Vector
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 the Java 2 platform v1.2, 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 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.
Collection
,
List
,
ArrayList
,
LinkedList
, Serialized FormField Summary | |
protected int |
capacityIncrement
The amount by which the capacity of the vector is automatically incremented when its size becomes greater than its capacity. |
protected int |
elementCount
The number of valid components in this Vector object. |
protected Object[] |
elementData
The array buffer into which the components of the vector are stored. |
Fields inherited from class java.util.AbstractList |
modCount |
Constructor Summary | |
Vector()
Constructs an empty vector so that its internal data array has size 10 and its standard capacity increment is zero. |
|
Vector(Collection c)
Constructs a vector containing the elements of the specified collection, in the order they are returned by the collection's iterator. |
|
Vector(int initialCapacity)
Constructs an empty vector with the specified initial capacity and with its capacity increment equal to zero. |
|
Vector(int initialCapacity,
int capacityIncrement)
Constructs an empty vector with the specified initial capacity and capacity increment. |
Method Summary | |
void |
add(int index,
Object element)
Inserts the specified element at the specified position in this Vector. |
boolean |
add(Object o)
Appends the specified element to the end of this Vector. |
boolean |
addAll(Collection c)
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. |
boolean |
addAll(int index,
Collection c)
Inserts all of the elements in in the specified Collection into this Vector at the specified position. |
void |
addElement(Object obj)
Adds the specified component to the end of this vector, increasing its size by one. |
int |
capacity()
Returns the current capacity of this vector. |
void |
clear()
Removes all of the elements from this Vector. |
Object |
clone()
Returns a clone of this vector. |
boolean |
contains(Object elem)
Tests if the specified object is a component in this vector. |
boolean |
containsAll(Collection c)
Returns true if this Vector contains all of the elements in the specified Collection. |
void |
copyInto(Object[] anArray)
Copies the components of this vector into the specified array. |
Object |
elementAt(int index)
Returns the component at the specified index. |
Enumeration |
elements()
Returns an enumeration of the components of this vector. |
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. |
boolean |
equals(Object o)
Compares the specified Object with this Vector for equality. |
Object |
firstElement()
Returns the first component (the item at index 0) of this vector. |
Object |
get(int index)
Returns the element at the specified position in this Vector. |
int |
hashCode()
Returns the hash code value for this Vector. |
int |
indexOf(Object elem)
Searches for the first occurence of the given argument, testing for equality using the equals method. |
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. |
void |
insertElementAt(Object obj,
int index)
Inserts the specified object as a component in this vector at the specified index . |
boolean |
isEmpty()
Tests if this vector has no components. |
Object |
lastElement()
Returns the last component of the vector. |
int |
lastIndexOf(Object elem)
Returns the index of the last occurrence of the specified object in this vector. |
int |
lastIndexOf(Object elem,
int index)
Searches backwards for the specified object, starting from the specified index, and returns an index to it. |
Object |
remove(int index)
Removes the element at the specified position in this Vector. |
boolean |
remove(Object o)
Removes the first occurrence of the specified element in this Vector If the Vector does not contain the element, it is unchanged. |
boolean |
removeAll(Collection c)
Removes from this Vector all of its elements that are contained in the specified Collection. |
void |
removeAllElements()
Removes all components from this vector and sets its size to zero. |
boolean |
removeElement(Object obj)
Removes the first (lowest-indexed) occurrence of the argument from this vector. |
void |
removeElementAt(int index)
Deletes the component at the specified index. |
protected void |
removeRange(int fromIndex,
int toIndex)
Removes from this List all of the elements whose index is between fromIndex, inclusive and toIndex, exclusive. |
boolean |
retainAll(Collection c)
Retains only the elements in this Vector that are contained in the specified Collection. |
Object |
set(int index,
Object element)
Replaces the element at the specified position in this Vector with the specified element. |
void |
setElementAt(Object obj,
int index)
Sets the component at the specified index of this
vector to be the specified object. |
void |
setSize(int newSize)
Sets the size of this vector. |
int |
size()
Returns the number of components in this vector. |
List |
subList(int fromIndex,
int toIndex)
Returns a view of the portion of this List between fromIndex, inclusive, and toIndex, exclusive. |
Object[] |
toArray()
Returns an array containing all of the elements in this Vector in the correct order. |
Object[] |
toArray(Object[] a)
Returns an array containing all of the elements in this Vector in the correct order. |
String |
toString()
Returns a string representation of this Vector, containing the String representation of each element. |
void |
trimToSize()
Trims the capacity of this vector to be the vector's current size. |
Methods inherited from class java.util.AbstractList |
iterator, listIterator, listIterator |
Methods inherited from class java.lang.Object |
finalize, getClass, notify, notifyAll, wait, wait, wait |
Methods inherited from interface java.util.List |
iterator, listIterator, listIterator |
Field Detail |
protected Object[] elementData
Any array elements following the last element in the Vector are null.
protected int elementCount
protected int capacityIncrement
Constructor Detail |
public Vector(int initialCapacity, int capacityIncrement)
initialCapacity
- the initial capacity of the vector.capacityIncrement
- the amount by which the capacity is
increased when the vector overflows.IllegalArgumentException
- if the specified initial capacity
is negativepublic Vector(int initialCapacity)
initialCapacity
- the initial capacity of the vector.IllegalArgumentException
- if the specified initial capacity
is negativepublic Vector()
public Vector(Collection c)
c
- the collection whose elements are to be placed into this
vector.Method Detail |
public void copyInto(Object[] anArray)
anArray
- the array into which the components get copied.public void trimToSize()
public 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, with a larger one. The size of the new data array will be the old size plus capacityIncrement, unless the value of capacityIncrement is less than or equal to zero, 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.
minCapacity
- the desired minimum capacity.public void setSize(int newSize)
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.newSize
- the new size of this vector.ArrayIndexOutOfBoundsException
- if new size is negative.public int capacity()
public int size()
size
in interface List
size
in class AbstractCollection
public boolean isEmpty()
isEmpty
in interface List
isEmpty
in class AbstractCollection
true
if and only if this vector has
no components, that is, its size is zero;
false
otherwise.public Enumeration elements()
Enumeration
,
Iterator
public boolean contains(Object elem)
contains
in interface List
contains
in class AbstractCollection
elem
- an object.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.public int indexOf(Object elem)
equals
method.indexOf
in interface List
indexOf
in class AbstractList
elem
- an object.-1
if the object is not found.Object.equals(Object)
public int indexOf(Object elem, int index)
index
, and testing for equality using
the equals
method.elem
- an object.index
- the non-negative index to start searching from.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. (Returns -1
if index >= the
current size of this Vector.)IndexOutOfBoundsException
- if index is negative.Object.equals(Object)
public int lastIndexOf(Object elem)
lastIndexOf
in interface List
lastIndexOf
in class AbstractList
elem
- the desired component.-1
if the object is not found.public int lastIndexOf(Object elem, int index)
elem
- the desired component.index
- the index to start searching from.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.
(Returns -1
if index is negative.)IndexOutOfBoundsException
- if index is greater
than or equal to the current size of this vector.public Object elementAt(int index)
This method is identical in functionality to the get method (which is part of the List interface).
index
- an index into this vector.ArrayIndexOutOfBoundsException
- if the index
is negative or not less than the current size of this
Vector object.
given.get(int)
,
List
public Object firstElement()
NoSuchElementException
- if this vector has no components.public Object lastElement()
size() - 1
.NoSuchElementException
- if this vector is empty.public void setElementAt(Object obj, int index)
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.
obj
- what the component is to be set to.index
- the specified index.ArrayIndexOutOfBoundsException
- if the index was invalid.size()
,
List
,
set(int, java.lang.Object)
public void removeElementAt(int index)
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.
index
- the index of the object to remove.ArrayIndexOutOfBoundsException
- if the index was invalid.size()
,
remove(int)
,
List
public void insertElementAt(Object obj, int index)
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. (If the
index is equal to the current size of the vector, the new element
is appended to 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.
obj
- the component to insert.index
- where to insert the new component.ArrayIndexOutOfBoundsException
- if the index was invalid.size()
,
add(int, Object)
,
List
public void addElement(Object obj)
This method is identical in functionality to the add(Object) method (which is part of the List interface).
obj
- the component to be added.add(Object)
,
List
public boolean removeElement(Object obj)
This method is identical in functionality to the remove(Object) method (which is part of the List interface).
obj
- the component to be removed.true
if the argument was a component of this
vector; false
otherwise.List.remove(Object)
,
List
public void removeAllElements()
This method is identical in functionality to the clear method (which is part of the List interface).
clear()
,
List
public Object clone()
clone
in class Object
public Object[] toArray()
toArray
in interface List
toArray
in class AbstractCollection
public Object[] toArray(Object[] a)
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.
toArray
in interface List
toArray
in class AbstractCollection
a
- the array into which the elements of the Vector are to
be stored, if it is big enough; otherwise, a new array of the
same runtime type is allocated for this purpose.ArrayStoreException
- the runtime type of a is not a supertype
of the runtime type of every element in this Vector.public Object get(int index)
get
in interface List
get
in class AbstractList
index
- index of element to return.ArrayIndexOutOfBoundsException
- index is out of range (index
< 0 || index >= size()).public Object set(int index, Object element)
set
in interface List
set
in class AbstractList
index
- index of element to replace.element
- element to be stored at the specified position.ArrayIndexOutOfBoundsException
- index out of range
(index < 0 || index >= size()).IllegalArgumentException
- fromIndex > toIndex.public boolean add(Object o)
add
in interface List
add
in class AbstractList
o
- element to be appended to this Vector.public boolean remove(Object o)
(o==null ? get(i)==null : o.equals(get(i)))
(if such
an element exists).remove
in interface List
remove
in class AbstractCollection
o
- element to be removed from this Vector, if present.public void add(int index, Object element)
add
in interface List
add
in class AbstractList
index
- index at which the specified element is to be inserted.element
- element to be inserted.ArrayIndexOutOfBoundsException
- index is out of range
(index < 0 || index > size()).public Object remove(int index)
remove
in interface List
remove
in class AbstractList
index
- the index of the element to removed.ArrayIndexOutOfBoundsException
- index out of range (index
< 0 || index >= size()).public void clear()
clear
in interface List
clear
in class AbstractList
public boolean containsAll(Collection c)
containsAll
in interface List
containsAll
in class AbstractCollection
public boolean addAll(Collection c)
addAll
in interface List
addAll
in class AbstractCollection
c
- elements to be inserted into this Vector.ArrayIndexOutOfBoundsException
- index out of range (index
< 0 || index > size()).public boolean removeAll(Collection c)
removeAll
in interface List
removeAll
in class AbstractCollection
public boolean retainAll(Collection c)
retainAll
in interface List
retainAll
in class AbstractCollection
public boolean addAll(int index, Collection c)
addAll
in interface List
addAll
in class AbstractList
index
- index at which to insert first element
from the specified collection.c
- elements to be inserted into this Vector.ArrayIndexOutOfBoundsException
- index out of range (index
< 0 || index > size()).public boolean equals(Object o)
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.equals
in interface List
equals
in class AbstractList
o
- the Object to be compared for equality with this Vector.public int hashCode()
hashCode
in interface List
hashCode
in class AbstractList
java.util.List
Object.hashCode()
,
Object.equals(Object)
,
List.equals(Object)
public String toString()
toString
in class AbstractCollection
java.util.AbstractCollection
public List subList(int fromIndex, int toIndex)
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.)
subList
in interface List
subList
in class AbstractList
fromIndex
- low endpoint (inclusive) of the subList.toIndex
- high endpoint (exclusive) of the subList.IndexOutOfBoundsException
- endpoint index value out of range
(fromIndex < 0 || toIndex > size)
IllegalArgumentException
- endpoint indices out of order
(fromIndex > toIndex)
protected void removeRange(int fromIndex, int toIndex)
removeRange
in class AbstractList
fromIndex
- index of first element to be removed.toIndex
- index after last element to be removed.
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JavaTM 2 Platform Std. Ed. v1.3.1 |
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SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
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