Added in API level 1

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>

Known direct subclasses

Stack<E>

Stack<E> The Stack class represents a last-in-first-out (LIFO) stack of objects.

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:

Collection
LinkedList

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 `Vector` object.
`protected Object[]`	`elementData` The array buffer into which the components of the vector are stored.

Inherited fields

From class java.util.AbstractList


    protected
    
    
    int

modCount

The number of times this list has been structurally modified.

Public constructors
`Vector()` Constructs an empty vector so that its internal data array has size `10` and its standard capacity increment is zero.
`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 `true` if 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)`
`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(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 `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<? 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 `Spliterator` over 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.

Protected methods
`void`	`removeRange(int fromIndex, int toIndex)` Removes from this list all of the elements whose index is between `fromIndex`, inclusive, and `toIndex`, exclusive.

Inherited methods

From class


        
          java.util.AbstractList

`void`	`add(int index, E element)` Inserts the specified element at the specified position in this list (optional operation).
`boolean`	`add(E e)` Appends the specified element to the end of this list (optional operation).
`boolean`	`addAll(int index, Collection<? extends E> c)` Inserts all of the elements in the specified collection into this list at the specified position (optional operation).
`void`	`clear()` Removes all of the elements from this list (optional operation).
`boolean`	`equals(Object o)` Compares the specified object with this list for equality.
`abstract E`	`get(int index)` Returns the element at the specified position in this list.
`int`	`hashCode()` Returns the hash code value for this list.
`int`	`indexOf(Object o)` Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
`Iterator<E>`	`iterator()` Returns an iterator over the elements in this list in proper sequence.
`int`	`lastIndexOf(Object o)` Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.
`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).
`E`	`remove(int index)` Removes the element at the specified position in this list (optional operation).
`void`	`removeRange(int fromIndex, int toIndex)` Removes from this list all of the elements whose index is between `fromIndex`, inclusive, and `toIndex`, exclusive.
`E`	`set(int index, E element)` Replaces the element at the specified position in this list with the specified element (optional operation).
`List<E>`	`subList(int fromIndex, int toIndex)` Returns a view of the portion of this list between the specified `fromIndex`, inclusive, and `toIndex`, exclusive.

From class


        
          java.util.AbstractCollection

`boolean`	`add(E e)` Ensures that this collection contains the specified element (optional operation).
`boolean`	`addAll(Collection<? extends E> c)` Adds all of the elements in the specified collection to this collection (optional operation).
`void`	`clear()` Removes all of the elements from this collection (optional operation).
`boolean`	`contains(Object o)` Returns `true` if this collection contains the specified element.
`boolean`	`containsAll(Collection<?> c)` Returns `true` if this collection contains all of the elements in the specified collection.
`boolean`	`isEmpty()` Returns `true` if this collection contains no elements.
`abstract Iterator<E>`	`iterator()` Returns an iterator over the elements contained in this collection.
`boolean`	`remove(Object o)` Removes a single instance of the specified element from this collection, if it is present (optional operation).
`boolean`	`removeAll(Collection<?> c)` Removes all of this collection's elements that are also contained in the specified collection (optional operation).
`boolean`	`retainAll(Collection<?> c)` Retains only the elements in this collection that are contained in the specified collection (optional operation).
`abstract int`	`size()` Returns the number of elements in this collection.
`<T> T[]`	`toArray(T[] a)` Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.
`Object[]`	`toArray()` Returns an array containing all of the elements in this collection.
`String`	`toString()` Returns a string representation of this collection.

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

From interface


        
          java.util.List

`abstract boolean`	`add(E e)` Appends the specified element to the end of this list (optional operation).
`abstract void`	`add(int index, E element)` Inserts the specified element at the specified position in this list (optional operation).
`abstract boolean`	`addAll(Collection<? extends E> c)` Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection's iterator (optional operation).
`abstract boolean`	`addAll(int index, Collection<? extends E> c)` Inserts all of the elements in the specified collection into this list at the specified position (optional operation).
`default void`	`addFirst(E e)` Adds an element as the first element of this collection (optional operation).
`default void`	`addLast(E e)` Adds an element as the last element of this collection (optional operation).
`abstract void`	`clear()` Removes all of the elements from this list (optional operation).
`abstract boolean`	`contains(Object o)` Returns `true` if this list contains the specified element.
`abstract boolean`	`containsAll(Collection<?> c)` Returns `true` if this list contains all of the elements of the specified collection.
`static <E> List<E>`	`copyOf(Collection<? extends E> coll)` Returns an unmodifiable List containing the elements of the given Collection, in its iteration order.
`abstract boolean`	`equals(Object o)` Compares the specified object with this list for equality.
`abstract E`	`get(int index)` Returns the element at the specified position in this list.
`default E`	`getFirst()` Gets the first element of this collection.
`default E`	`getLast()` Gets the last element of this collection.
`abstract int`	`hashCode()` Returns the hash code value for this list.
`abstract int`	`indexOf(Object o)` Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
`abstract boolean`	`isEmpty()` Returns `true` if this list contains no elements.
`abstract Iterator<E>`	`iterator()` Returns an iterator over the elements in this list in proper sequence.
`abstract int`	`lastIndexOf(Object o)` Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.
`abstract 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.
`abstract ListIterator<E>`	`listIterator()` Returns a list iterator over the elements in this list (in proper sequence).
`static <E> List<E>`	`of(E e1, E e2, E e3)` Returns an unmodifiable list containing three elements.
`static <E> List<E>`	`of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9)` Returns an unmodifiable list containing nine elements.
`static <E> List<E>`	`of(E e1, E e2, E e3, E e4, E e5)` Returns an unmodifiable list containing five elements.
`static <E> List<E>`	`of(E e1, E e2, E e3, E e4, E e5, E e6)` Returns an unmodifiable list containing six elements.
`static <E> List<E>`	`of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8)` Returns an unmodifiable list containing eight elements.
`static <E> List<E>`	`of(E... elements)` Returns an unmodifiable list containing an arbitrary number of elements.
`static <E> List<E>`	`of()` Returns an unmodifiable list containing zero elements.
`static <E> List<E>`	`of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9, E e10)` Returns an unmodifiable list containing ten elements.
`static <E> List<E>`	`of(E e1, E e2)` Returns an unmodifiable list containing two elements.
`static <E> List<E>`	`of(E e1, E e2, E e3, E e4, E e5, E e6, E e7)` Returns an unmodifiable list containing seven elements.
`static <E> List<E>`	`of(E e1, E e2, E e3, E e4)` Returns an unmodifiable list containing four elements.
`static <E> List<E>`	`of(E e1)` Returns an unmodifiable list containing one element.
`abstract E`	`remove(int index)` Removes the element at the specified position in this list (optional operation).
`abstract boolean`	`remove(Object o)` Removes the first occurrence of the specified element from this list, if it is present (optional operation).
`abstract boolean`	`removeAll(Collection<?> c)` Removes from this list all of its elements that are contained in the specified collection (optional operation).
`default E`	`removeFirst()` Removes and returns the first element of this collection (optional operation).
`default E`	`removeLast()` Removes and returns the last element of this collection (optional operation).
`default void`	`replaceAll(UnaryOperator<E> operator)` Replaces each element of this list with the result of applying the operator to that element.
`abstract boolean`	`retainAll(Collection<?> c)` Retains only the elements in this list that are contained in the specified collection (optional operation).
`default List<E>`	`reversed()` Returns a reverse-ordered view of this collection.
`abstract E`	`set(int index, E element)` Replaces the element at the specified position in this list with the specified element (optional operation).
`abstract int`	`size()` Returns the number of elements in this list.
`default void`	`sort(Comparator<? super E> c)` Sorts this list according to the order induced by the specified `Comparator`.
`default Spliterator<E>`	`spliterator()` Creates a `Spliterator` over the elements in this list.
`abstract List<E>`	`subList(int fromIndex, int toIndex)` Returns a view of the portion of this list between the specified `fromIndex`, inclusive, and `toIndex`, exclusive.
`abstract Object[]`	`toArray()` Returns an array containing all of the elements in this list in proper sequence (from first to last element).
`abstract <T> T[]`	`toArray(T[] a)` Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array.

From interface


        
          java.util.Collection

`abstract boolean`	`add(E e)` Ensures that this collection contains the specified element (optional operation).
`abstract boolean`	`addAll(Collection<? extends E> c)` Adds all of the elements in the specified collection to this collection (optional operation).
`abstract void`	`clear()` Removes all of the elements from this collection (optional operation).
`abstract boolean`	`contains(Object o)` Returns `true` if this collection contains the specified element.
`abstract boolean`	`containsAll(Collection<?> c)` Returns `true` if this collection contains all of the elements in the specified collection.
`abstract boolean`	`equals(Object o)` Compares the specified object with this collection for equality.
`abstract int`	`hashCode()` Returns the hash code value for this collection.
`abstract boolean`	`isEmpty()` Returns `true` if this collection contains no elements.
`abstract Iterator<E>`	`iterator()` Returns an iterator over the elements in this collection.
`default Stream<E>`	`parallelStream()` Returns a possibly parallel `Stream` with this collection as its source.
`abstract boolean`	`remove(Object o)` Removes a single instance of the specified element from this collection, if it is present (optional operation).
`abstract boolean`	`removeAll(Collection<?> c)` Removes all of this collection's elements that are also contained in the specified collection (optional operation).
`default boolean`	`removeIf(Predicate<? super E> filter)` Removes all of the elements of this collection that satisfy the given predicate.
`abstract boolean`	`retainAll(Collection<?> c)` Retains only the elements in this collection that are contained in the specified collection (optional operation).
`abstract int`	`size()` Returns the number of elements in this collection.
`default Spliterator<E>`	`spliterator()` Creates a `Spliterator` over the elements in this collection.
`default Stream<E>`	`stream()` Returns a sequential `Stream` with this collection as its source.
`abstract <T> T[]`	`toArray(T[] a)` Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.
`abstract Object[]`	`toArray()` Returns an array containing all of the elements in this collection.
`default <T> T[]`	`toArray(IntFunction<T[]> generator)` Returns an array containing all of the elements in this collection, using the provided `generator` function to allocate the returned array.

From interface


        
          java.util.SequencedCollection

`default void`	`addFirst(E e)` Adds an element as the first element of this collection (optional operation).
`default void`	`addLast(E e)` Adds an element as the last element of this collection (optional operation).
`default E`	`getFirst()` Gets the first element of this collection.
`default E`	`getLast()` Gets the last element of this collection.
`default E`	`removeFirst()` Removes and returns the first element of this collection (optional operation).
`default E`	`removeLast()` Removes and returns the last element of this collection (optional operation).
`abstract SequencedCollection<E>`	`reversed()` Returns a reverse-ordered view of this collection.

From interface


        
          java.lang.Iterable

`default void`	`forEach(Consumer<? super T> action)` Performs the given action for each element of the `Iterable` until all elements have been processed or the action throws an exception.
`abstract Iterator<E>`	`iterator()` Returns an iterator over elements of type `T`.
`default Spliterator<E>`	`spliterator()` Creates a `Spliterator` over the elements described by this `Iterable`.

Fields

capacityIncrement

Added in API level 1

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

Added in API level 1

protected int elementCount

The number of valid components in this Vector object. Components elementData[0] through elementData[elementCount-1] are the actual items.

elementData

Added in API level 1

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

Added in API level 1

public Vector ()

Constructs an empty vector so that its internal data array has size 10 and its standard capacity increment is zero.

Vector

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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.

Returns
`Object`	a clone of this vector

contains

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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:

toArray(Object[])

elementAt

Added in API level 1

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

Added in API level 1

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:

Iterator

ensureCapacity

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 24

public void forEach (Consumer<? super E> action)

Parameters
`action`	`Consumer`

Throws
`NullPointerException`

get

Added in API level 1

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

Added in API level 1

public int hashCode ()

Returns the hash code value for this Vector.

Returns
`int`	the hash code value for this list

indexOf

Added in API level 1

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

Added in API level 1

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:

Object.equals(Object)

insertElementAt

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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:

listIterator(int)

remove

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 24

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

Added in API level 24

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

public int size ()

Returns the number of components in this vector.

Returns
`int`	the number of components in this vector

sort

Added in API level 24

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

Added in API level 24

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

Added in API level 1

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.)

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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

Added in API level 1

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