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.
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.
Collection,
LinkedList,
Serialized Form
| Modifier and Type | Field and 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 and Description |
|---|
Vector()
Constructs an empty vector so that its internal data array has size
10 and its standard capacity increment is zero.
|
Vector(Collection
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.
|
| Modifier and Type | Method and Description |
|---|---|
boolean |
add(E e)
Appends the specified element to the end of this Vector.
|
void |
add(int index, E element)
Inserts the specified element at the specified position in this Vector.
|
boolean |
addAll(Collection
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
Inserts all of the elements in the specified Collection into this Vector at the specified position.
|
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
Returns
true if this vector contains the specified element.
|
boolean |
containsAll(Collection
Returns true if this Vector contains all of the elements in the specified Collection.
|
void |
copyInto(Object
Copies the components of this vector into the specified array.
|
E |
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
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(Consumer
Performs the given action for each element of the
Iterable until all elements have been processed or the action throws an exception.
|
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
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
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(E 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.
|
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(Object
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
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(int index)
Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list.
|
E |
remove(int index)
Removes the element at the specified position in this Vector.
|
boolean |
remove(Object
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
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
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
Removes all of the elements of this collection that satisfy the given predicate.
|
protected void |
removeRange(int fromIndex, int toIndex)
Removes from this list all of the elements whose index is between
fromIndex, inclusive, and
toIndex, exclusive.
|
void |
replaceAll(UnaryOperator
Replaces each element of this list with the result of applying the operator to that element.
|
boolean |
retainAll(Collection
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
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.
|
void |
sort(Comparator
Sorts this list using the supplied
Comparator to compare elements.
|
Spliterator |
spliterator()
Creates a
late-binding and
fail-fast
Spliterator over the elements in this list.
|
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.
|
<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.
|
finalize, getClass, notify, notifyAll, wait, wait, waitparallelStream, streamprotected 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 vector
capacityIncrement - the amount by which the capacity is increased when the vector overflows
IllegalArgumentException - if the specified initial capacity is negative
public Vector(int initialCapacity)
initialCapacity - the initial capacity of the vector
IllegalArgumentException - if the specified initial capacity is negative
public 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 vector
NullPointerException - if the specified collection is null
public void copyInto(Object[] anArray)
k in this vector is copied into component
k of
anArray.
anArray - the array into which the components get copied
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
toArray(Object[])
public 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 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 the new size is negative
public int capacity()
elementData of this vector)
public int size()
size in interface
Collection<E>
size in interface
List<E>
size in class
AbstractCollection<E>
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.
Iterator
public boolean contains(Objecto)
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
(o==null ? e==null : o.equals(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 tested
true if this vector contains the specified element
public int indexOf(Objecto)
i such that
(o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.
public int indexOf(Objecto, int index)
index, or returns -1 if the element is not found. More formally, returns the lowest index
i such that
(i >= index && (o==null ? get(i)==null : o.equals(get(i)))), or -1 if there is no such index.
o - element to search for
index - index to start searching from
index or later in the vector;
-1 if the element is not found.
IndexOutOfBoundsException - if the specified index is negative
Object.equals(Object)
public int lastIndexOf(Objecto)
i such that
(o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.
lastIndexOf in interface
List<E>
lastIndexOf in class
AbstractList<E>
o - element to search for
public int lastIndexOf(Objecto, int index)
index, or returns -1 if the element is not found. More formally, returns the highest index
i such that
(i <= index && (o==null ? get(i)==null : o.equals(get(i)))), or -1 if there is no such index.
o - element to search for
index - index to start searching backwards from
index 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 vector
public 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 vector
ArrayIndexOutOfBoundsException - if the index is out of range (
index < 0 || index >= size())
public E firstElement()
0) of this vector.
NoSuchElementException - if this vector has no components
public E lastElement()
size() - 1.
NoSuchElementException - if this vector is empty
public 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 to
index - the specified index
ArrayIndexOutOfBoundsException - 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 remove
ArrayIndexOutOfBoundsException - 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 insert
index - where to insert the new component
ArrayIndexOutOfBoundsException - 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 added
public boolean removeElement(Objectobj)
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.
public void removeAllElements()
public Objectclone()
Vector object.
public Object[] toArray()
toArray in interface
Collection<E>
toArray in interface
List<E>
toArray in class
AbstractCollection<E>
Arrays.asList(Object[])
public <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 - the runtime type of the array to contain the collection
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 is not a supertype of the runtime type of every element in this Vector
NullPointerException - if the given array is null
public E get(int index)
get in interface
List<E>
get in class
AbstractList<E>
index - index of the element to return
ArrayIndexOutOfBoundsException - 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 replace
element - element to be stored at the specified position
ArrayIndexOutOfBoundsException - 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 Vector
true (as specified by
Collection.add(E) )
public boolean remove(Objecto)
(o==null ? get(i)==null : o.equals(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 present
public 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 inserted
element - element to be inserted
ArrayIndexOutOfBoundsException - 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 removed
ArrayIndexOutOfBoundsException - 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 Vector
NullPointerException - if the specified collection is null
AbstractCollection.contains(Object)
public 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 Vector
true if this Vector changed as a result of the call
NullPointerException - if the specified collection is null
AbstractCollection.add(Object)
public 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 Vector
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
AbstractCollection.remove(Object) ,
AbstractCollection.contains(Object)
public 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 null
AbstractCollection.remove(Object) ,
AbstractCollection.contains(Object)
public 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 collection
c - elements to be inserted into this Vector
true if this Vector changed as a result of the call
ArrayIndexOutOfBoundsException - if the index is out of range (
index < 0 || index > size())
NullPointerException - if the specified collection is null
public boolean equals(Objecto)
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
Collection<E>
equals in interface
List<E>
equals in class
AbstractList<E>
o - the Object to be compared for equality with this Vector
Object.hashCode() ,
HashMap
public int hashCode()
hashCode in interface
Collection<E>
hashCode in interface
List<E>
hashCode in class
AbstractList<E>
Object.equals(java.lang.Object) ,
System.identityHashCode(java.lang.Object)
public StringtoString()
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 subList
toIndex - high endpoint (exclusive) of the subList
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)
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 removed
toIndex - index after last element to be removed
public 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>
listIterator(int)
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. Unless otherwise specified by the implementing class, actions are performed in the order of iteration (if an iteration order is specified). Exceptions thrown by the action are relayed to the caller.
public boolean removeIf(Predicate<? super E> filter)
Collection
removeIf in interface
Collection<E>
filter - a predicate which returns
true for elements to be removed
true if any elements were removed
public void replaceAll(UnaryOperator<E> operator)
List
replaceAll in interface
List<E>
operator - the operator to apply to each element
public void sort(Comparator<? super E> c)
List
Comparator to compare elements.
sort in interface
List<E>
c - the
Comparator used to compare list elements. A
null value indicates that the elements'
natural ordering should be used
public Spliterator<E> spliterator()
Spliterator over the elements in this list.
The Spliterator reports Spliterator, Spliterator, and Spliterator. Overriding implementations should document the reporting of additional characteristic values.
spliterator in interface
Iterable<E>
spliterator in interface
Collection<E>
spliterator in interface
List<E>
Spliterator over the elements in this list