E
- Type of component elementsSerializable
, Cloneable
, Iterable<E>
, Collection<E>
, List<E>
, RandomAccess
, SequencedCollection<E>
Stack
public class Vector<E> extends AbstractList<E> implements List<E>, RandomAccess, Cloneable, Serializable
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 this class'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 the elements
method are not fail-fast; if the Vector is structurally modified at any time after the enumeration is created then the results of enumerating are undefined.
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. If a thread-safe implementation is not needed, it is recommended to use ArrayList
in place of Vector
.
Modifier and Type | Field | Description |
---|---|---|
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. |
modCount
Constructor | Description |
---|---|
Vector() |
Constructs an empty vector so that its internal data array has size 10 and its standard capacity increment is zero. |
Vector |
Constructs an empty vector with the specified initial capacity and with its capacity increment equal to zero. |
Vector |
Constructs an empty vector with the specified initial capacity and capacity increment. |
Vector |
Constructs a vector containing the elements of the specified collection, in the order they are returned by the collection's iterator. |
Modifier and Type | Method | Description |
---|---|---|
void |
add |
Inserts the specified element at the specified position in this Vector. |
boolean |
add |
Appends the specified element to the end of this Vector. |
boolean |
addAll |
Inserts all of the elements in the specified Collection into this Vector at the specified position. |
boolean |
addAll |
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. |
void |
addElement |
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 |
Returns true if this vector contains the specified element. |
boolean |
containsAll |
Returns true if this Vector contains all of the elements in the specified Collection. |
void |
copyInto |
Copies the components of this vector into the specified array. |
E |
elementAt |
Returns the component at the specified index. |
Enumeration |
elements() |
Returns an enumeration of the components of this vector. |
void |
ensureCapacity |
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 |
Compares the specified Object with this Vector for equality. |
E |
firstElement() |
Returns the first component (the item at index 0 ) of this vector. |
void |
forEach |
Performs the given action for each element of the Iterable until all elements have been processed or the action throws an exception. |
E |
get |
Returns the element at the specified position in this Vector. |
int |
hashCode() |
Returns the hash code value for this Vector. |
int |
indexOf |
Returns the index of the first occurrence of the specified element in this vector, or -1 if this vector does not contain the element. |
int |
indexOf |
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. |
void |
insertElementAt |
Inserts the specified object as a component in this vector at the specified index . |
boolean |
isEmpty() |
Tests if this vector has no components. |
Iterator |
iterator() |
Returns an iterator over the elements in this list in proper sequence. |
E |
lastElement() |
Returns the last component of the vector. |
int |
lastIndexOf |
Returns the index of the last occurrence of the specified element in this vector, or -1 if this vector does not contain the element. |
int |
lastIndexOf |
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. |
ListIterator |
listIterator() |
Returns a list iterator over the elements in this list (in proper sequence). |
ListIterator |
listIterator |
Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list. |
E |
remove |
Removes the element at the specified position in this Vector. |
boolean |
remove |
Removes the first occurrence of the specified element in this Vector If the Vector does not contain the element, it is unchanged. |
boolean |
removeAll |
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 |
Removes the first (lowest-indexed) occurrence of the argument from this vector. |
void |
removeElementAt |
Deletes the component at the specified index. |
boolean |
removeIf |
Removes all of the elements of this collection that satisfy the given predicate. |
protected void |
removeRange |
Removes from this list all of the elements whose index is between fromIndex , inclusive, and toIndex , exclusive. |
void |
replaceAll |
Replaces each element of this list with the result of applying the operator to that element. |
boolean |
retainAll |
Retains only the elements in this Vector that are contained in the specified Collection. |
E |
set |
Replaces the element at the specified position in this Vector with the specified element. |
void |
setElementAt |
Sets the component at the specified index of this vector to be the specified object. |
void |
setSize |
Sets the size of this vector. |
int |
size() |
Returns the number of components in this vector. |
Spliterator |
spliterator() |
Creates a late-binding and fail-fast Spliterator over the elements in this list. |
List |
subList |
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. |
<T> T[] |
toArray |
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. |
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. |
parallelStream, stream, toArray
addFirst, addLast, getFirst, getLast, removeFirst, removeLast, reversed, sort
protected Object[] elementData
Any array elements following the last element in the Vector are null.
protected int elementCount
Vector
object. Components elementData[0]
through elementData[elementCount-1]
are the actual items.protected int capacityIncrement
public Vector(int initialCapacity, int capacityIncrement)
initialCapacity
- the initial capacity of the vectorcapacityIncrement
- the amount by which the capacity is increased when the vector overflowsIllegalArgumentException
- if the specified initial capacity is negativepublic Vector(int initialCapacity)
initialCapacity
- the initial capacity of the vectorIllegalArgumentException
- if the specified initial capacity is negativepublic Vector()
10
and its standard capacity increment is zero.public Vector(Collection<? extends E> c)
c
- the collection whose elements are to be placed into this vectorNullPointerException
- if the specified collection is nullpublic void copyInto(Object[] anArray)
k
in this vector is copied into component k
of anArray
.anArray
- the array into which the components get copiedNullPointerException
- if the given array is nullIndexOutOfBoundsException
- if the specified array is not large enough to hold all the components of this vectorArrayStoreException
- if a component of this vector is not of a runtime type that can be stored in the specified arraypublic void trimToSize()
elementData
, with a smaller one. An application can use this operation to minimize the storage of a vector.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 capacitypublic 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 vectorArrayIndexOutOfBoundsException
- if the new size is negativepublic int capacity()
elementData
of this vector)public int size()
public boolean isEmpty()
isEmpty
in interface Collection<E>
isEmpty
in interface List<E>
isEmpty
in class AbstractCollection<E>
true
if and only if this vector has no components, that is, its size is zero; false
otherwise.public Enumeration<E> elements()
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. If the vector is structurally modified while enumerating over the elements then the results of enumerating are undefined.public boolean contains(Object o)
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 Objects.equals(o, e)
.contains
in interface Collection<E>
contains
in interface List<E>
contains
in class AbstractCollection<E>
o
- element whose presence in this vector is to be testedtrue
if this vector contains the specified elementpublic int indexOf(Object o)
i
such that Objects.equals(o, get(i))
, or -1 if there is no such index.public int indexOf(Object o, int index)
index
, or returns -1 if the element is not found. More formally, returns the lowest index i
such that (i >= index && Objects.equals(o, get(i)))
, or -1 if there is no such index.o
- element to search forindex
- index to start searching fromindex
or later in the vector; -1
if the element is not found.IndexOutOfBoundsException
- if the specified index is negativepublic int lastIndexOf(Object o)
i
such that Objects.equals(o, get(i))
, or -1 if there is no such index.lastIndexOf
in interface List<E>
lastIndexOf
in class AbstractList<E>
o
- element to search forpublic int lastIndexOf(Object o, int index)
index
, or returns -1 if the element is not found. More formally, returns the highest index i
such that (i <= index && Objects.equals(o, get(i)))
, or -1 if there is no such index.o
- element to search forindex
- index to start searching backwards fromindex
in this vector; -1 if the element is not found.IndexOutOfBoundsException
- if the specified index is greater than or equal to the current size of this vectorpublic E elementAt(int index)
This method is identical in functionality to the get(int)
method (which is part of the List
interface).
index
- an index into this vectorArrayIndexOutOfBoundsException
- if the index is out of range (index < 0 || index >= size()
)public E firstElement()
0
) of this vector.NoSuchElementException
- if this vector has no componentspublic E lastElement()
size() - 1
NoSuchElementException
- if this vector is emptypublic void setElementAt(E 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(int, E)
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 toindex
- the specified indexArrayIndexOutOfBoundsException
- if the index is out of range (index < 0 || index >= size()
)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(int)
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 removeArrayIndexOutOfBoundsException
- if the index is out of range (index < 0 || index >= size()
)public void insertElementAt(E 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(int, E)
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 insertindex
- where to insert the new componentArrayIndexOutOfBoundsException
- if the index is out of range (index < 0 || index > size()
)public void addElement(E obj)
This method is identical in functionality to the add(E)
method (which is part of the List
interface).
obj
- the component to be addedpublic 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 removedtrue
if the argument was a component of this vector; false
otherwise.public void removeAllElements()
public Object clone()
Vector
object.public Object[] toArray()
toArray
in interface Collection<E>
toArray
in interface List<E>
toArray
in class AbstractCollection<E>
Object
, containing all of the elements in this collectionpublic <T> T[] toArray(T[] 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 Collection<E>
toArray
in interface List<E>
toArray
in class AbstractCollection<E>
T
- type of array elements. The same type as <E>
or a supertype of <E>
.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
- if the runtime type of a, <T>
, is not a supertype of the runtime type, <E>
, of every element in this VectorNullPointerException
- if the given array is nullpublic E get(int index)
get
in interface List<E>
get
in class AbstractList<E>
index
- index of the element to returnArrayIndexOutOfBoundsException
- if the index is out of range (index < 0 || index >= size()
)public E set(int index, E element)
set
in interface List<E>
set
in class AbstractList<E>
index
- index of the element to replaceelement
- element to be stored at the specified positionArrayIndexOutOfBoundsException
- if the index is out of range (index < 0 || index >= size()
)public boolean add(E e)
add
in interface Collection<E>
add
in interface List<E>
add
in class AbstractList<E>
e
- element to be appended to this Vectortrue
(as specified by Collection.add(E)
)public boolean remove(Object o)
Objects.equals(o, get(i))
(if such an element exists).remove
in interface Collection<E>
remove
in interface List<E>
remove
in class AbstractCollection<E>
o
- element to be removed from this Vector, if presentpublic void add(int index, E element)
add
in interface List<E>
add
in class AbstractList<E>
index
- index at which the specified element is to be insertedelement
- element to be insertedArrayIndexOutOfBoundsException
- if the index is out of range (index < 0 || index > size()
)public E remove(int index)
remove
in interface List<E>
remove
in class AbstractList<E>
index
- the index of the element to be removedArrayIndexOutOfBoundsException
- if the index is out of range (index < 0 || index >= size()
)public void clear()
clear
in interface Collection<E>
clear
in interface List<E>
clear
in class AbstractList<E>
public boolean containsAll(Collection<?> c)
containsAll
in interface Collection<E>
containsAll
in interface List<E>
containsAll
in class AbstractCollection<E>
c
- a collection whose elements will be tested for containment in this VectorNullPointerException
- if the specified collection is nullpublic boolean addAll(Collection<? extends E> c)
addAll
in interface Collection<E>
addAll
in interface List<E>
addAll
in class AbstractCollection<E>
c
- elements to be inserted into this Vectortrue
if this Vector changed as a result of the callNullPointerException
- if the specified collection is nullpublic boolean removeAll(Collection<?> c)
removeAll
in interface Collection<E>
removeAll
in interface List<E>
removeAll
in class AbstractCollection<E>
c
- a collection of elements to be removed from the VectorClassCastException
- if the types of one or more elements in this vector are incompatible with the specified collection (optional)NullPointerException
- if this vector contains one or more null elements and the specified collection does not support null elements (optional), or if the specified collection is nullpublic boolean retainAll(Collection<?> c)
retainAll
in interface Collection<E>
retainAll
in interface List<E>
retainAll
in class AbstractCollection<E>
c
- a collection of elements to be retained in this Vector (all other elements are removed)ClassCastException
- if the types of one or more elements in this vector are incompatible with the specified collection (optional)NullPointerException
- if this vector contains one or more null elements and the specified collection does not support null elements (optional), or if the specified collection is nullpublic boolean removeIf(Predicate<? super E> filter)
Collection
removeIf
in interface Collection<E>
filter
- a predicate which returns true
for elements to be removedtrue
if any elements were removedNullPointerException
- if the specified filter is nullpublic boolean addAll(int index, Collection<? extends E> c)
addAll
in interface List<E>
addAll
in class AbstractList<E>
index
- index at which to insert the first element from the specified collectionc
- elements to be inserted into this Vectortrue
if this Vector changed as a result of the callArrayIndexOutOfBoundsException
- if the index is out of range (index < 0 || index > size()
)NullPointerException
- if the specified collection is nullpublic boolean equals(Object o)
e1
and e2
are equal if Objects.equals(e1, e2)
.) In other words, two Lists are defined to be equal if they contain the same elements in the same order.equals
in interface Collection<E>
equals
in interface List<E>
equals
in class AbstractList<E>
o
- the Object to be compared for equality with this Vectorpublic int hashCode()
hashCode
in interface Collection<E>
hashCode
in interface List<E>
hashCode
in class AbstractList<E>
public String toString()
toString
in class AbstractCollection<E>
public List<E> 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<E>
subList
in class AbstractList<E>
fromIndex
- low endpoint (inclusive) of the subListtoIndex
- high endpoint (exclusive) of the subListIndexOutOfBoundsException
- if an endpoint index value is out of range (fromIndex < 0 || toIndex > size)
IllegalArgumentException
- if the endpoint indices are out of order (fromIndex > toIndex)
protected void removeRange(int fromIndex, int toIndex)
fromIndex
, inclusive, and toIndex
, exclusive. Shifts any succeeding elements to the left (reduces their index). This call shortens the list by (toIndex - fromIndex)
elements. (If toIndex==fromIndex
, this operation has no effect.)removeRange
in class AbstractList<E>
fromIndex
- index of first element to be removedtoIndex
- index after last element to be removedpublic ListIterator<E> listIterator(int index)
next
. An initial call to previous
would return the element with the specified index minus one. The returned list iterator is fail-fast.
listIterator
in interface List<E>
listIterator
in class AbstractList<E>
index
- index of the first element to be returned from the list iterator (by a call to next
)IndexOutOfBoundsException
- if the index is out of range (index < 0 || index > size()
)public ListIterator<E> listIterator()
The returned list iterator is fail-fast.
listIterator
in interface List<E>
listIterator
in class AbstractList<E>
public Iterator<E> iterator()
The returned iterator is fail-fast.
public void forEach(Consumer<? super E> action)
Iterable
Iterable
until all elements have been processed or the action throws an exception. Actions are performed in the order of iteration, if that order is specified. Exceptions thrown by the action are relayed to the caller. The behavior of this method is unspecified if the action performs side-effects that modify the underlying source of elements, unless an overriding class has specified a concurrent modification policy.
forEach
in interface Iterable<E>
action
- The action to be performed for each elementNullPointerException
- if the specified action is nullpublic void replaceAll(UnaryOperator<E> operator)
List
replaceAll
in interface List<E>
operator
- the operator to apply to each elementNullPointerException
- if the specified operator is null or if the operator result is a null value and this list does not permit null elements (optional)public Spliterator<E> spliterator()
Spliterator
over the elements in this list. The Spliterator
reports Spliterator.SIZED
, Spliterator.SUBSIZED
, and Spliterator.ORDERED
. Overriding implementations should document the reporting of additional characteristic values.
spliterator
in interface Collection<E>
spliterator
in interface Iterable<E>
spliterator
in interface List<E>
Spliterator
over the elements in this list
© 1993, 2023, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/Vector.html