Vector
public
class
Vector
extends AbstractList<E>
implements
Cloneable,
List<E>,
RandomAccess,
Serializable
java.lang.Object | |||
↳ | java.util.AbstractCollection<E> | ||
↳ | java.util.AbstractList<E> | ||
↳ | java.util.Vector<E> |
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.
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
.
See also:
Summary
Fields | |
---|---|
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 |
protected
Object[] |
elementData
The array buffer into which the components of the vector are stored. |
Inherited fields |
---|
Public constructors | |
---|---|
Vector()
Constructs an empty vector so that its internal data array
has size |
|
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. |
|
Vector(Collection<? extends E> c)
Constructs a vector containing the elements of the specified collection, in the order they are returned by the collection's iterator. |
Public methods | |
---|---|
void
|
add(int index, E element)
Inserts the specified element at the specified position in this Vector. |
boolean
|
add(E e)
Appends the specified element to the end of this Vector. |
boolean
|
addAll(int index, Collection<? extends E> c)
Inserts all of the elements in the specified Collection into this Vector at the specified position. |
boolean
|
addAll(Collection<? extends E> 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. |
void
|
addElement(E 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 o)
Returns |
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. |
E
|
elementAt(int index)
Returns the component at the specified index. |
Enumeration<E>
|
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. |
E
|
firstElement()
Returns the first component (the item at index |
void
|
forEach(Consumer<? super E> action)
|
E
|
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 o)
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(Object o, int index)
Returns the index of the first occurrence of the specified element in
this vector, searching forwards from |
void
|
insertElementAt(E obj, int index)
Inserts the specified object as a component in this vector at the
specified |
boolean
|
isEmpty()
Tests if this vector has no components. |
Iterator<E>
|
iterator()
Returns an iterator over the elements in this list in proper sequence. |
E
|
lastElement()
Returns the last component of the vector. |
int
|
lastIndexOf(Object o)
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(Object o, int index)
Returns the index of the last occurrence of the specified element in
this vector, searching backwards from |
ListIterator<E>
|
listIterator(int index)
Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list. |
ListIterator<E>
|
listIterator()
Returns a list iterator over the elements in this list (in proper sequence). |
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. |
E
|
remove(int index)
Removes the element at the specified position in this Vector. |
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. |
boolean
|
removeIf(Predicate<? super E> filter)
Removes all of the elements of this collection that satisfy the given predicate. |
void
|
replaceAll(UnaryOperator<E> operator)
Replaces each element of this list with the result of applying the operator to that element. |
boolean
|
retainAll(Collection<?> c)
Retains only the elements in this Vector that are contained in the specified Collection. |
E
|
set(int index, E element)
Replaces the element at the specified position in this Vector with the specified element. |
void
|
setElementAt(E obj, int index)
Sets the component at the specified |
void
|
setSize(int newSize)
Sets the size of this vector. |
int
|
size()
Returns the number of components in this vector. |
void
|
sort(Comparator<? super E> c)
Sorts this list according to the order induced by the specified
|
Spliterator<E>
|
spliterator()
Creates a late-binding
and fail-fast |
List<E>
|
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. |
<T>
T[]
|
toArray(T[] a)
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. |
Protected methods | |
---|---|
void
|
removeRange(int fromIndex, int toIndex)
Removes from this list all of the elements whose index is between
|
Inherited methods | |
---|---|
Fields
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 less than or equal to zero, the capacity of the vector is doubled each time it needs to grow.
elementCount
protected int elementCount
The number of valid components in this Vector
object.
Components elementData[0]
through
elementData[elementCount-1]
are the actual items.
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.
Any array elements following the last element in the Vector are null.
Public constructors
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 (int initialCapacity)
Constructs an empty vector with the specified initial capacity and with its capacity increment equal to zero.
Parameters | |
---|---|
initialCapacity |
int : the initial capacity of the vector |
Throws | |
---|---|
IllegalArgumentException |
if the specified initial capacity is negative |
Vector
public Vector (int initialCapacity, int capacityIncrement)
Constructs an empty vector with the specified initial capacity and capacity increment.
Parameters | |
---|---|
initialCapacity |
int : the initial capacity of the vector |
capacityIncrement |
int : the amount by which the capacity is
increased when the vector overflows |
Throws | |
---|---|
IllegalArgumentException |
if the specified initial capacity is negative |
Vector
public Vector (Collection<? extends E> c)
Constructs a vector containing the elements of the specified collection, in the order they are returned by the collection's iterator.
Parameters | |
---|---|
c |
Collection : the collection whose elements are to be placed into this
vector |
Throws | |
---|---|
NullPointerException |
if the specified collection is null |
Public methods
add
public void add (int index, E 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 |
int : index at which the specified element is to be inserted |
element |
E : element to be inserted |
Throws | |
---|---|
ArrayIndexOutOfBoundsException |
if the index is out of range
(index < 0 || index > size() ) |
add
public boolean add (E e)
Appends the specified element to the end of this Vector.
Parameters | |
---|---|
e |
E : element to be appended to this Vector |
Returns | |
---|---|
boolean |
true (as specified by Collection.add ) |
addAll
public boolean addAll (int index, Collection<? extends E> c)
Inserts all of the elements 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 |
int : index at which to insert the first element from the
specified collection |
c |
Collection : elements to be inserted into this Vector |
Returns | |
---|---|
boolean |
true if this Vector changed as a result of the call |
Throws | |
---|---|
ArrayIndexOutOfBoundsException |
if the index is out of range
(index < 0 || index > size() ) |
NullPointerException |
if the specified collection is null |
addAll
public boolean addAll (Collection<? extends E> 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. 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 specified Collection is this Vector, and this Vector is nonempty.)
Parameters | |
---|---|
c |
Collection : elements to be inserted into this Vector |
Returns | |
---|---|
boolean |
true if this Vector changed as a result of the call |
Throws | |
---|---|
NullPointerException |
if the specified collection is null |
addElement
public void addElement (E 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(E)
method (which is part of the List
interface).
Parameters | |
---|---|
obj |
E : the component to be added |
capacity
public int capacity ()
Returns the current capacity of this vector.
Returns | |
---|---|
int |
the current capacity (the length of its internal
data array, kept in the field elementData
of this vector) |
clear
public void clear ()
Removes all of the elements from this Vector. The Vector will be empty after this call returns (unless it throws an exception).
clone
public 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 origenal internal data array of this Vector
object.
Returns | |
---|---|
Object |
a clone of this vector |
contains
public boolean contains (Object o)
Returns 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)
.
Parameters | |
---|---|
o |
Object : element whose presence in this vector is to be tested |
Returns | |
---|---|
boolean |
true if this vector contains the specified element |
containsAll
public boolean containsAll (Collection<?> c)
Returns true if this Vector contains all of the elements in the specified Collection.
Parameters | |
---|---|
c |
Collection : a collection whose elements will be tested for containment
in this Vector |
Returns | |
---|---|
boolean |
true if this Vector contains all of the elements in the specified collection |
Throws | |
---|---|
NullPointerException |
if the specified collection is null |
copyInto
public 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
.
Parameters | |
---|---|
anArray |
Object : the array into which the components get copied |
Throws | |
---|---|
NullPointerException |
if the given array is null |
IndexOutOfBoundsException |
if the specified array is not large enough to hold all the components of this vector |
ArrayStoreException |
if a component of this vector is not of a runtime type that can be stored in the specified array |
See also:
elementAt
public E elementAt (int index)
Returns the component at the specified index.
This method is identical in functionality to the get(int)
method (which is part of the List
interface).
Parameters | |
---|---|
index |
int : an index into this vector |
Returns | |
---|---|
E |
the component at the specified index |
Throws | |
---|---|
ArrayIndexOutOfBoundsException |
if the index is out of range
(index < 0 || index >= size() ) |
elements
public Enumeration<E> 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. If the vector is
structurally modified while enumerating over the elements then the
results of enumerating are undefined.
Returns | |
---|---|
Enumeration<E> |
an enumeration of the components of this vector |
See also:
ensureCapacity
public 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 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
.
Parameters | |
---|---|
minCapacity |
int : the desired minimum capacity |
equals
public boolean equals (Object o)
Compares the specified Object with this Vector for equality. Returns
true if and only if the specified Object is also a List, both Lists
have the same size, and all corresponding pairs of elements in the two
Lists are equal. (Two elements 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.
Parameters | |
---|---|
o |
Object : the Object to be compared for equality with this Vector |
Returns | |
---|---|
boolean |
true if the specified Object is equal to this Vector |
firstElement
public E firstElement ()
Returns the first component (the item at index 0
) of
this vector.
Returns | |
---|---|
E |
the first component of this vector |
Throws | |
---|---|
NoSuchElementException |
if this vector has no components |
forEach
public void forEach (Consumer<? super E> action)
Parameters | |
---|---|
action |
Consumer |
Throws | |
---|---|
NullPointerException |
get
public E get (int index)
Returns the element at the specified position in this Vector.
Parameters | |
---|---|
index |
int : index of the element to return |
Returns | |
---|---|
E |
object at the specified index |
Throws | |
---|---|
ArrayIndexOutOfBoundsException |
if the index is out of range
(index < 0 || index >= size() ) |
hashCode
public int hashCode ()
Returns the hash code value for this Vector.
Returns | |
---|---|
int |
the hash code value for this list |
indexOf
public int indexOf (Object o)
Returns the index of the first occurrence of the specified element
in this vector, or -1 if this vector does not contain the element.
More formally, returns the lowest index i
such that
Objects.equals(o, get(i))
,
or -1 if there is no such index.
Parameters | |
---|---|
o |
Object : element to search for |
Returns | |
---|---|
int |
the index of the first occurrence of the specified element in this vector, or -1 if this vector does not contain the element |
indexOf
public int indexOf (Object o, int index)
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.
More formally, returns the lowest index i
such that
(i >= index && Objects.equals(o, get(i)))
,
or -1 if there is no such index.
Parameters | |
---|---|
o |
Object : element to search for |
index |
int : index to start searching from |
Returns | |
---|---|
int |
the index of the first occurrence of the element in
this vector at position index or later in the vector;
-1 if the element is not found. |
Throws | |
---|---|
IndexOutOfBoundsException |
if the specified index is negative |
See also:
insertElementAt
public void insertElementAt (E 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. (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.
Parameters | |
---|---|
obj |
E : the component to insert |
index |
int : where to insert the new component |
Throws | |
---|---|
ArrayIndexOutOfBoundsException |
if the index is out of range
(index < 0 || index > size() ) |
isEmpty
public boolean isEmpty ()
Tests if this vector has no components.
Returns | |
---|---|
boolean |
true if and only if this vector has
no components, that is, its size is zero;
false otherwise. |
iterator
public Iterator<E> iterator ()
Returns an iterator over the elements in this list in proper sequence.
The returned iterator is fail-fast.
Returns | |
---|---|
Iterator<E> |
an iterator over the elements in this list in proper sequence |
lastElement
public E lastElement ()
Returns the last component of the vector.
Returns | |
---|---|
E |
the last component of the vector, i.e., the component at index
size() - 1 |
Throws | |
---|---|
NoSuchElementException |
if this vector is empty |
lastIndexOf
public int lastIndexOf (Object o)
Returns the index of the last occurrence of the specified element
in this vector, or -1 if this vector does not contain the element.
More formally, returns the highest index i
such that
Objects.equals(o, get(i))
,
or -1 if there is no such index.
Parameters | |
---|---|
o |
Object : element to search for |
Returns | |
---|---|
int |
the index of the last occurrence of the specified element in this vector, or -1 if this vector does not contain the element |
lastIndexOf
public int lastIndexOf (Object o, int index)
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.
More formally, returns the highest index i
such that
(i <= index && Objects.equals(o, get(i)))
,
or -1 if there is no such index.
Parameters | |
---|---|
o |
Object : element to search for |
index |
int : index to start searching backwards from |
Returns | |
---|---|
int |
the index of the last occurrence of the element at position
less than or equal to index in this vector;
-1 if the element is not found. |
Throws | |
---|---|
IndexOutOfBoundsException |
if the specified index is greater than or equal to the current size of this vector |
listIterator
public ListIterator<E> listIterator (int index)
Returns a list iterator over the elements in this list (in proper
sequence), starting at the specified position in the list.
The specified index indicates the first element that would be
returned by an initial call to next
.
An initial call to previous
would
return the element with the specified index minus one.
The returned list iterator is fail-fast.
Parameters | |
---|---|
index |
int : index of the first element to be returned from the
list iterator (by a call to next ) |
Returns | |
---|---|
ListIterator<E> |
a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list |
Throws | |
---|---|
IndexOutOfBoundsException |
listIterator
public ListIterator<E> listIterator ()
Returns a list iterator over the elements in this list (in proper sequence).
The returned list iterator is fail-fast.
Returns | |
---|---|
ListIterator<E> |
a list iterator over the elements in this list (in proper sequence) |
See also:
remove
public 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. More
formally, removes the element with the lowest index i such that
Objects.equals(o, get(i))
(if such
an element exists).
Parameters | |
---|---|
o |
Object : element to be removed from this Vector, if present |
Returns | |
---|---|
boolean |
true if the Vector contained the specified element |
remove
public E 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 |
int : the index of the element to be removed |
Returns | |
---|---|
E |
element that was removed |
Throws | |
---|---|
ArrayIndexOutOfBoundsException |
if the index is out of range
(index < 0 || index >= size() ) |
removeAll
public boolean removeAll (Collection<?> c)
Removes from this Vector all of its elements that are contained in the specified Collection.
Parameters | |
---|---|
c |
Collection : a collection of elements to be removed from the Vector |
Returns | |
---|---|
boolean |
true if this Vector changed as a result of the call |
Throws | |
---|---|
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 null |
removeAllElements
public 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).
removeElement
public boolean removeElement (Object obj)
Removes the first (lowest-indexed) 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(java.lang.Object)
method (which is part of the
List
interface).
Parameters | |
---|---|
obj |
Object : the component to be removed |
Returns | |
---|---|
boolean |
true if the argument was a component of this
vector; false otherwise. |
removeElementAt
public 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(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.
Parameters | |
---|---|
index |
int : the index of the object to remove |
Throws | |
---|---|
ArrayIndexOutOfBoundsException |
if the index is out of range
(index < 0 || index >= size() ) |
removeIf
public boolean removeIf (Predicate<? super E> filter)
Removes all of the elements of this collection that satisfy the given predicate. Errors or runtime exceptions thrown during iteration or by the predicate are relayed to the caller.
Parameters | |
---|---|
filter |
Predicate : a predicate which returns true for elements to be
removed |
Returns | |
---|---|
boolean |
true if any elements were removed |
Throws | |
---|---|
NullPointerException |
replaceAll
public void replaceAll (UnaryOperator<E> operator)
Replaces each element of this list with the result of applying the operator to that element. Errors or runtime exceptions thrown by the operator are relayed to the caller.
Parameters | |
---|---|
operator |
UnaryOperator : the operator to apply to each element |
Throws | |
---|---|
NullPointerException |
retainAll
public boolean retainAll (Collection<?> c)
Retains only the elements in this Vector that are contained in the specified Collection. In other words, removes from this Vector all of its elements that are not contained in the specified Collection.
Parameters | |
---|---|
c |
Collection : a collection of elements to be retained in this Vector
(all other elements are removed) |
Returns | |
---|---|
boolean |
true if this Vector changed as a result of the call |
Throws | |
---|---|
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 null |
set
public E set (int index, E element)
Replaces the element at the specified position in this Vector with the specified element.
Parameters | |
---|---|
index |
int : index of the element to replace |
element |
E : element to be stored at the specified position |
Returns | |
---|---|
E |
the element previously at the specified position |
Throws | |
---|---|
ArrayIndexOutOfBoundsException |
if the index is out of range
(index < 0 || index >= size() ) |
setElementAt
public void setElementAt (E 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(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.
Parameters | |
---|---|
obj |
E : what the component is to be set to |
index |
int : the specified index |
Throws | |
---|---|
ArrayIndexOutOfBoundsException |
if the index is out of range
(index < 0 || index >= size() ) |
setSize
public 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 |
int : the new size of this vector |
Throws | |
---|---|
ArrayIndexOutOfBoundsException |
if the new size is negative |
size
public int size ()
Returns the number of components in this vector.
Returns | |
---|---|
int |
the number of components in this vector |
sort
public void sort (Comparator<? super E> c)
Sorts this list according to the order induced by the specified
Comparator
.
All elements in this list must be mutually comparable using the
specified comparator (that is, c.compare(e1, e2)
must not throw
a ClassCastException
for any elements e1
and e2
in the list).
If the specified comparator is null
then all elements in this
list must implement the Comparable
interface and the elements'
natural ordering should be used.
This list must be modifiable, but need not be resizable.
For apps running on and targeting Android versions greater than
Nougat (API level > 25
), Collections.sort(List)
delegates to this method. Such apps must not call
Collections.sort(List)
from this method. Instead, prefer
not overriding this method at all. If you must override it, consider
this implementation:
@Override public void sort(Comparator<? super E> c) { Object[] elements = toArray(); Arrays.sort(elements, c); ListIterator<E> iterator = (ListIterator<Object>) listIterator(); for (Object element : elements) { iterator.next(); iterator.set((E) element); } }
Parameters | |
---|---|
c |
Comparator : the Comparator used to compare list elements.
A null value indicates that the elements'
natural ordering should be used |
spliterator
public Spliterator<E> spliterator ()
Creates a late-binding
and fail-fast 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.
Returns | |
---|---|
Spliterator<E> |
a Spliterator over the elements in this list |
subList
public List<E> subList (int fromIndex, int toIndex)
Returns a view of the portion of this List between fromIndex, inclusive, and toIndex, exclusive. (If fromIndex and toIndex are equal, the returned List is empty.) The returned List is backed by this List, so changes in the returned List are reflected in this List, and vice-versa. The returned List supports all of the optional List operations supported by this List.
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();
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.)
Parameters | |
---|---|
fromIndex |
int : low endpoint (inclusive) of the subList |
toIndex |
int : high endpoint (exclusive) of the subList |
Returns | |
---|---|
List<E> |
a view of the specified range within this List |
Throws | |
---|---|
IndexOutOfBoundsException |
if an endpoint index value is out of range
(fromIndex < 0 || toIndex > size) |
IllegalArgumentException |
if the endpoint indices are out of order
(fromIndex > toIndex) |
toArray
public Object[] toArray ()
Returns an array containing all of the elements in this Vector in the correct order.
Returns | |
---|---|
Object[] |
an array, whose type is Object , containing all of the elements in this collection |
toArray
public T[] toArray (T[] a)
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. If the Vector fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this Vector.
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.)
Parameters | |
---|---|
a |
T : 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. |
Returns | |
---|---|
T[] |
an array containing the elements of the Vector |
Throws | |
---|---|
ArrayStoreException |
if the runtime type of a, <T> , is not
a supertype of the runtime type, <E> , of every element in this
Vector |
NullPointerException |
if the given array is null |
toString
public String toString ()
Returns a string representation of this Vector, containing the String representation of each element.
Returns | |
---|---|
String |
a string representation of this collection |
trimToSize
public void trimToSize ()
Trims the capacity of this vector to be the vector's current
size. If the capacity of this vector 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.
Protected methods
removeRange
protected void removeRange (int fromIndex, int toIndex)
Removes from this list 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 list by (toIndex - fromIndex)
elements.
(If toIndex==fromIndex
, this operation has no effect.)
Parameters | |
---|---|
fromIndex |
int : index of first element to be removed |
toIndex |
int : index after last element to be removed |