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 | capacityIncrementThe amount by which the capacity of the vector is automatically
 incremented when its size becomes greater than its capacity. | 
| protected int | elementCountThe number of valid components in this  Vectorobject. | 
| protected Object[] | elementDataThe 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  10and its standard capacity increment is
 zero. | 
| 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. | 
| 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<? 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. | 
| boolean | addAll(int index,
      Collection<? extends E> c)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 o)Returns  trueif this vector contains the specified element. | 
| 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  0) of
 this vector. | 
| void | forEach(Consumer<? super E> action)Performs the given action for each element of the  Iterableuntil 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 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  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<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  index, or returns -1 if
 the element is not found. | 
| ListIterator<E> | listIterator()Returns a list iterator over the elements in this list (in proper
 sequence). | 
| 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. | 
| E | remove(int index)Removes the element at the specified position in this Vector. | 
| boolean | remove(Object o)Removes the first occurrence of the specified element in this Vector
 If the Vector does not contain the element, it is unchanged. | 
| boolean | removeAll(Collection<?> c)Removes from this Vector all of its elements that are contained in the
 specified Collection. | 
| void | removeAllElements()Removes all components from this vector and sets its size to zero. | 
| boolean | removeElement(Object obj)Removes the first (lowest-indexed) occurrence of the argument
 from this vector. | 
| void | removeElementAt(int index)Deletes the component at the specified index. | 
| boolean | removeIf(Predicate<? super E> filter)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, andtoIndex, exclusive. | 
| 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  indexof 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<? super E> c)Sorts this list according to the order induced by the specified
  Comparator. | 
| Spliterator<E> | spliterator()Creates a late-binding
 and fail-fast  Spliteratorover the elements in this
 list. | 
| 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. | 
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 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 arraytoArray(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 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()
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.Iteratorpublic 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
 (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)
i such that
 (o==null ? get(i)==null : o.equals(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 && (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)
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)
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)
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>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 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)
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)
(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)
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 nullAbstractCollection.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 Vectortrue if this Vector changed as a result of the callNullPointerException - if the specified collection is nullAbstractCollection.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 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)
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)
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 (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(), 
HashMappublic 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 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>listIterator(int)public Iterator<E> iterator()
The returned iterator is fail-fast.
public void forEach(Consumer<? super E> action)
IterableIterable
 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)
CollectionremoveIf 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)
ListreplaceAll in interface List<E>operator - the operator to apply to each elementpublic void sort(Comparator<? super E> c)
ListComparator.
 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()
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 Submit a bug or feature 
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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