public class Vector<E> extends AbstractList<E> implements List<E>, RandomAccess, Cloneable, Serializable
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.
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 Formprotected 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.
protected int elementCount
The number of valid components in this Vector object. Components elementData[0] through elementData[elementCount-1] are the actual items.
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.
public Vector(int initialCapacity,
int capacityIncrement) Constructs an empty vector with the specified initial capacity and capacity increment.
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)
Constructs an empty vector with the specified initial capacity and with its capacity increment equal to zero.
initialCapacity - the initial capacity of the vectorIllegalArgumentException - if the specified initial capacity is negativepublic Vector()
Constructs an empty vector so that its internal data array has size 10 and its standard capacity increment is zero.
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.
c - the collection whose elements are to be placed into this vectorNullPointerException - if the specified collection is nullpublic 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.
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 arraytoArray(Object[])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.
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.
minCapacity - the desired minimum capacitypublic 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.
newSize - the new size of this vectorArrayIndexOutOfBoundsException - if the new size is negativepublic int capacity()
Returns the current capacity of this vector.
elementData of this vector)public int size()
Returns the number of components in this vector.
size in interface Collection<E>
size in interface List<E>
size in class AbstractCollection<E>
public boolean isEmpty()
Tests if this vector has no components.
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()
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.
Iteratorpublic 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 (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 testedtrue if this vector contains the specified elementpublic 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 (o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.
indexOf in interface List<E>
indexOf in class AbstractList<E>
o - element to search forpublic 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 && (o==null ? get(i)==null : o.equals(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 negativeObject.equals(Object)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 (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 forpublic 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 && (o==null ? get(i)==null : o.equals(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)
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).
index - an index into this vectorArrayIndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())public E firstElement()
Returns the first component (the item at index 0) of this vector.
NoSuchElementException - if this vector has no componentspublic E lastElement()
Returns the last component of the vector.
size() - 1.NoSuchElementException - if this vector is emptypublic 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.
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)
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.
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) 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.
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)
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).
obj - the component to be addedpublic 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(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()
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).
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 original internal data array of this Vector object.
public Object[] toArray()
Returns an array containing all of the elements in this Vector in the correct order.
toArray in interface Collection<E>
toArray in interface List<E>
toArray in class AbstractCollection<E>
Arrays.asList(Object[])public <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. 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.)
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 collectiona - 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 VectorNullPointerException - if the given array is nullpublic E get(int index)
Returns the element at the specified position in this Vector.
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) Replaces the element at the specified position in this Vector with the specified 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)
Appends the specified element to the end of this Vector.
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)
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 (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 presentpublic 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).
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)
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.
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()
Removes all of the elements from this Vector. The Vector will be empty after this call returns (unless it throws an exception).
clear in interface Collection<E>
clear in interface List<E>
clear in class AbstractList<E>
public boolean containsAll(Collection<?> c)
Returns true if this Vector contains all of the elements in the specified Collection.
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 nullAbstractCollection.contains(Object)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.)
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 nullAbstractCollection.add(Object)public boolean removeAll(Collection<?> c)
Removes from this Vector all of its elements that are contained in the specified Collection.
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 nullAbstractCollection.remove(Object), AbstractCollection.contains(Object)
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.
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 nullAbstractCollection.remove(Object), AbstractCollection.contains(Object)
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.
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)
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 (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 VectorObject.hashCode(), HashMap
public int hashCode()
Returns the hash code value for this Vector.
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 String toString()
Returns a string representation of this Vector, containing the String representation of each element.
toString in class AbstractCollection<E>
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();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) 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.)
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)
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.
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()
Returns a list iterator over the elements in this list (in proper sequence).
The returned list iterator is fail-fast.
listIterator in interface List<E>
listIterator in class AbstractList<E>
listIterator(int)public Iterator<E> iterator()
Returns an iterator over the elements in this list in proper sequence.
The returned iterator is fail-fast.
iterator in interface Iterable<E>
iterator in interface Collection<E>
iterator in interface List<E>
iterator in class AbstractList<E>
public void forEach(Consumer<? super E> action)
Description copied from interface: Iterable
Performs the given action for each element of the 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.
forEach in interface Iterable<E>
action - The action to be performed for each elementpublic boolean removeIf(Predicate<? super E> filter)
Description copied from interface: Collection
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.
removeIf in interface Collection<E>
filter - a predicate which returns true for elements to be removedtrue if any elements were removedpublic void replaceAll(UnaryOperator<E> operator)
Description copied from interface: List
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.
replaceAll in interface List<E>
operator - the operator to apply to each elementpublic void sort(Comparator<? super E> c)
Description copied from interface: List
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.
sort in interface List<E>
c - the Comparator used to compare list elements. A null value indicates that the elements' natural ordering should be usedpublic 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.
spliterator in interface Iterable<E>
spliterator in interface Collection<E>
spliterator in interface List<E>
Spliterator over the elements in this list
© 1993–2017, 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.