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Class java.util.Vector

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

public class Vector

extends Object

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.

  protected Object elementData[]

The buffer.

  protected int elementCount

The number of elements.

  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.

  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.

  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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