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Vector Class in Java

Vector Class in Java

April 30th, 2019 Java

Vector Class in Java

  • Vector class extends AbstractList and implements List, RandomAccess, Cloneable, Serializable.
  • It is based on reserved memory storage called capacity.
  • It will maintain default capacity of 10 bytes. It allows user can define their own capacity based on constructor.
  • It allows to retrieve first and last element respectively.
  • It also a synchronized class like StringBuffer class.

Creating Vector:

Vector obj=new Vector();\\with default capacity of 10

Vector obj=new Vector(int);\\with userdefined capacity.

Vector obj=new Vector(int,int);\\With userdefined and incremental

Methods:

int capacity()

It returns the capacity reserved by the vector.

void ensureCapacity(int)

int – no.of bytes to store
It returns the more no.of bytes to reserve

void setSize(int)

int – size of the vector
Used to set the size for the vector.

E elementAt(int)

int – index of the element
It returns the specified indexed element like get(int)

E firstElement()

It returns the first element in the vector.

E lastElement()

It returns the last element in the vector.

void setElement(E,int)

E – Element , int –index to store
Used to set the Element in the specified index

void addElement(int)

add the element at last

void removeElementAt(int)

int – index to remove
It removes the Element in vector at specified index

void insertElementAt(E,int)

E – Element  , int – index to insert
Used to insert element in the specified index

Enumeration elements()

It returns the Elements to Enumeration interface

Example:

import java.util.*;
public class ListVector
{      public static void main(String args[])
{
Vector v=new VectoPreview (opens in a new window)r(2,3);
System.out.println("Capacity(before) :"+v.capacity());
System.out.println("Size of Vector(before):"+v.size());
v.add(2);
v.add(3);
v.add("asd");
v.add('d');
v.add("asd");
v.add('d');
System.out.println("Capacity (After):"+v.capacity());
System.out.println("Size of Vector(After):"+v.size());
System.out.println("Elements(Clone):"+v.clone());
System.out.println("First Elements:"+v.firstElement());
System.out.println("Last Elements:"+v.lastElement());
Enumeration e=v.elements();
while(e.hasMoreElements())
{
System.out.println("Elements :"+e.nextElement());
}
Iterator i=v.iterator();
while(i.hasNext())
{
System.out.println("Elements:"+i.next());
}
v.setElementAt("hello", 4);
System.out.println("Elements After setElementAt:"+v.clone());
v.removeElementAt(2);
System.out.println("Elements After removeElementAt:"+v.clone());
v.addElement("world");
System.out.println("Elements After addElement:"+v.clone());
System.out.println("Element at:"+v.elementAt(3));
}
}

Output:

Capacity(before) :2

Size of Vector(before):0

Capacity (After):8

Size of Vector(After):6

Elements(Clone):[2, 3, asd, d, asd, d]

First Elements:2

Last Elements:d

Elements :2

Elements :3

Elements :asd

Elements :d

Elements :asd

Elements :d

Elements:2

Elements:3

Elements:asd

Elements:d

Elements:asd

Elements:d

Elements After setElementAt:[2, 3, asd, d, hello, d]

Elements After removeElementAt:[2, 3, d, hello, d]

Elements After addElement:[2, 3, d, hello, d, world]

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