reference: 'Core Java', C.S.Hoortsman, JDK 1.3 API documentation                                   Oct 18 / /2000

One of the principle drawbacks of using arrays is they need to be fixed in length. They don't
lend themselves to dynamically changing size. A Vector is a java class that acts as a container
similar to an array but one which can grow (or shrink) in size. While arrays are a built-in feature
of the Java language Vector class is a regular java library class. Unlike arrays, which can be
specified for any type defined in Java (primitives, arrays, and Object types ), Vectors store one
generic type, Object. It is easy to add an item to a Vector but to get it back it has to be cast to
the appropriate type.

A Vector is created via one of it's a 4 constructors. Vector has an empty constructor and a
constructor that takes a Collection object. It also has a constuctor allowing setting the initial
capacity of the Vector, and a fourth constructor allows specifying the initial capacity and the
capacity increment. The capacity increment decides the size that the vector will grow by and
is automatically set to the size of the vector.

Vector implements the methods of the List interface plus about 15 other methods for a total of
about 40 methods. This shows you that Vector has quite a bit of  versatility absent in the array.

Vector v=new Vector( 5 );  // this is a Vector with it's size set to 5.

You can use add( ) and addElement( ) methods to add items to the Vector and remove( )
or removeElement( ) methods to remove items. Primitive types have to be 'wrapped' in
appropriate wrapper classes to be stored in a Vector. The elements( ) method will return
an Enumeration object which you can iterate with Enumeration's hasMoreElements( )
and nextElement( ) methods. elementAt( ) returns a component at a specified index.
Check the API documentation for details on Vector class.

Constructor Summary
 

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

Method List
 

void  add (int index,          Object element)	Inserts the specified element at the specified position in this Vector.
boolean add(Object o)	Appends the specified element to the end of this Vector.
boolean addAll(Collection 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 c)	Inserts all of the elements in in the specified Collection into  this Vector at the specified position.
void  addElement(Object obj)	Adds the specified component to the vector end, 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( )	new Returns a clone of this vector.
boolean contains(Object elem)	Tests if the specified object is a component in this vector.
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.
Object elementAt(int index)	Returns the component at the specified index.
Enumeration 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.
Object firstElement( )	Returns the first component (the item at index 0) of this vector.
Object 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 elem)	Searches for the first occurence of the given argument,  testing for equality using the equals method.
int  indexOf  (Object elem, int index)	Searches for the first occurence of the given argument,  beginning the search at index, and testing for equality   using the equals method.
void  insertElementAt (Object 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.
Object lastElement( )	Returns the last component of the vector.
int lastIndexOf(Object elem)	Returns the index of the last occurrence of the specified  object in this vector.
int lastIndexOf (Object elem, int index)	Searches backwards for the specified object, starting from the specified index, and returns an index to it.
Object 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.
protected void removeRange (int fromIndex, int toIndex)	Removes from this List all of the elements whose index is between fromIndex, inclusive and toIndex, exclusive.
boolean retainAll(Collection c)	Retains only the elements in this Vector that are contained in the specified Collection.
Object set (int index, Object element)	Replaces the element at the specified position in this Vector  with the specified element.
void setElementAt (Object 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.
List 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.
Object[] toArray(Object[] a)	Returns an array containing all of the elements in this Vector  in the correct order.
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.