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# Class java.util.Vector

    java.lang.Object
       |
       +----java.util.Vector

public class Vector
extends Object

Vector class (a growable array).

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 elements are added to the vector, the vector's storage increases in chunks the size of capacityIncrement. Setting the capacity to what you want before inserting a large number of objects will reduce the amount of incremental reallocation. You can safely ignore the capacity and the vector will still work correctly.

Version:
  1.19, 11 Feb 1995
Author:
  Jonathan Payne, Lee Boynton

##

capacityIncrement
  The size of the increment.
elementCount
  The number of elements.
elementData
  The buffer.

##

Vector(int, int)
  Constructs a vector with zero elements and the specified storage capacity and the specified capacityIncrement.
Vector(int)
  Constructs an empty vector with the specified storage capacity.
Vector()
  Construct an empty vector.

##

addElement(Object)
  Adds the specified object as the last element of the vector.
capacity()
  Returns the current capacity of the vector.
clone()
  Clone this vector.
contains(Object)
  Returns true if the specified object a a value of the collection.
copyInto(Object[])
  Copies the elements of this vector into the specified array.
elementAt(int)
  Returns the element at the specified index.
elements()
  Returns an enumeration of the elements.
ensureCapacity(int)
  Ensures that the vector has at least the specified capacity.
firstElement()
  Returns the first element of the sequence.
indexOf(Object)
  Searches for the specified object, starting from the first position and returns an index to it.
indexOf(Object, int)
  Searches for the specified object, starting from the specified position and return an index to it.
insertElementAt(Object, int)
  Inserts the specified object as an element at the specified index.
isEmpty()
  Returns true if the collection contains no values.
lastElement()
  Returns the last element of the sequence.
lastIndexOf(Object)
  Searches backwards for the specified object, starting from the last position and returns an index to it.
lastIndexOf(Object, int)
  Searches backwards for the specified object, starting from the specified position and returns an index to it.
removeAllElements()
  Removes all elements of the vector.
removeElement(Object)
  Removes the element from the vector.
removeElementAt(int)
  Deletes the element at the specified index.
setElementAt(Object, int)
  Sets the element at the specified index to be the specified object.
setSize(int)
  Sets the size of the vector.
size()
  Returns the number of elements in the vector.
toString()
  Converts the vector to a string.
trimToSize()
  Trims the vector's capacity down to size.

##

elementData

      protected Object elementData[]

  The buffer.

elementCount

      protected int elementCount

  The number of elements.

capacityIncrement

      protected int capacityIncrement

  The size of the increment. If it is 0 the size of the the buffer is doubled everytime it needs to grow.

##

Vector

      public Vector(int initialCapacity,
                    int capacityIncrement)

  Constructs a vector with zero elements and the specified storage capacity and the specified capacityIncrement.

Vector

      public Vector(int initialCapacity)

  Constructs an empty vector with the specified storage capacity.

Vector

      public Vector()

  Construct an empty vector.

##

copyInto

      public final synchronized void copyInto(Object anArray[])

  Copies the elements of this vector into the specified array.

trimToSize

      public final synchronized void trimToSize()

  Trims the vector's capacity down to size. Use this operation to minimize the storage of a vector. Subsequent insertions will cause reallocation.

ensureCapacity

      public final synchronized void ensureCapacity(int minCapacity)

  Ensures that the vector has at least the specified capacity.
  Parameters:
    minCapacity - the desired minimum capacity

setSize

      public final synchronized void setSize(int newSize)

  Sets the size of the vector. If the size shrinks, the extra elements (at the end of the vector) are lost; if the size increases, the new elements are set to null.

capacity

      public final int capacity()

  Returns the current capacity of the vector.

size

      public final int size()

  Returns the number of elements in the vector. Note that this is not the same as the vector's capacity.

isEmpty

      public final boolean isEmpty()

  Returns true if the collection contains no values.

elements

      public final synchronized Enumeration elements()

  Returns an enumeration of the elements. Use the Enumeration methods on the returned object to fetch the elements sequentially.

contains

      public final boolean contains(Object elem)

  Returns true if the specified object a a value of the collection.

indexOf

      public final int indexOf(Object elem)

  Searches for the specified object, starting from the first position and returns an index to it.
  Parameters:
    elem - the desired element
  Returns:
    the index of the element, or -1 if it was not found

indexOf

      public final synchronized int indexOf(Object elem,
                                            int index)

  Searches for the specified object, starting from the specified position and return an index to it.
  Parameters:
    elem - the desired element
    index - the index where to start searching
  Returns:
    the index of the element, or -1 if it was not found

lastIndexOf

      public final int lastIndexOf(Object elem)

  Searches backwards for the specified object, starting from the last position and returns an index to it.
  Parameters:
    elem - the desired element
  Returns:
    the index of the element, or -1 if it was not found

lastIndexOf

      public final synchronized int lastIndexOf(Object elem,
                                                int index)

  Searches backwards for the specified object, starting from the specified position and returns an index to it.
  Parameters:
    elem - the desired element
    index - the index where to start searching
  Returns:
    the index of the element, or -1 if it was not found

elementAt

      public final synchronized Object elementAt(int index)

  Returns the element at the specified index.
  Parameters:
    index - the index of the desired element
  Returns:
    the desired element
  Throws: ArrayIndexOutOfBoundsException
    Invalid index

firstElement

      public final synchronized Object firstElement()

  Returns the first element of the sequence.
  Throws: NoSuchElementException
    The sequence is empty.

lastElement

      public final synchronized Object lastElement()

  Returns the last element of the sequence.
  Throws: NoSuchElementException
    The sequence is empty.

setElementAt

      public final synchronized void setElementAt(Object obj,
                                                  int index)

  Sets the element at the specified index to be the specified object. The previous element at that position is discarded.
  Throws: ArrayIndexOutOfBoundsException
    Invalid index

removeElementAt

      public final synchronized void removeElementAt(int index)

  Deletes the element at the specified index. Elements with an index greater than index are moved down.
  Parameters:
    index - the element to remove
  Throws: ArrayIndexOutOfBoundsException
    Invalid index

insertElementAt

      public final synchronized void insertElementAt(Object obj,
                                                     int index)

  Inserts the specified object as an element at the specified index. Elements with an index greater or equal to the index are shifted up.
  Parameters:
    obj - the element to insert
    index - where to insert the new element
  Throws: ArrayIndexOutOfBoundsException
    invalid index

addElement

      public final synchronized void addElement(Object obj)

  Adds the specified object as the last element of the vector.
  Parameters:
    obj - the element to be added

removeElement

      public final synchronized boolean removeElement(Object obj)

  Removes the element from the vector. If the object occurs more than once, only the first is removed. If the object is not an element, returns false.
  Parameters:
    obj - the element to be removed
  Returns:
    true if the element was actually removed

removeAllElements

      public final synchronized void removeAllElements()

  Removes all elements of the vector. The vector becomes empty.

clone

      public synchronized Object clone()

  Clone this vector. The elements are not cloned.
  Overrides:
    clone in class Object

toString

      public final synchronized String toString()

  Converts the vector to a string. Useful for debugging.
  Overrides:
    toString in class Object

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