Vector Class

Vector Class
  • The underlying Data structure for the vector is resizable array or growable array.
  • Insertion order is preserved.
  • Duplicate objects are allowed.
  • β€˜null’ insertion is possible.
  • Heterogeneous objects are allowed.
  • Best choice if the frequent operation is retrieval.
  • Worst choice if the frequent operation is insertion or deletion in the middle.
  • Vector class implemented serializable, cloneable and RandomAccess Interfaces.
  • Every method present in Vector is synchronized and hence Vector is Thread safe.
Vector specific methods
To add objects
 1. add(Object o);-----Collection
 2. add(int index,Object o);-----List
 3. addElement(Object o);-----Vector 
To remove elements
 1. remove(Object o);--------Collection
 2. remove(int index);--------------List
 3. removeElement(Object o);----Vector
 4. removeElementAt(int index);-----Vector
 5. removeAllElements();-----Vector
 6. clear();-------Collection 
To get objects
 1. Object get(int index);---------------List
 2. Object elementAt(int index);-----Vector
 3. Object firstElement();--------------Vector
 4. Object lastElement();---------------Vector 
Other methods
 1. int size();//How many objects are added
 2. int capacity();//Total capacity
 3. Enumeration elements();
Constructors
1. Vector v=new Vector();
  • Creates an empty Vector object with default initial capacity 10.
  • Once Vector reaches its maximum capacity then a new Vector object will be created with double capacity. That is “newcapacity=currentcapacity*2”
 2. Vector v=new Vector(int initialcapacity);
 3. Vector v=new Vector(int initialcapacity, int incrementalcapacity);
 4. Vector v=new Vector(Collection c); 
package com.ashok.collections.linkedlist;

import java.util.Vector;
/**
 * 
 * @author ashok.mariyala
 *
 */
public class MyLinkedList {
   public static void main(String[] args) {
      Vector vector = new Vector();
      System.out.println(vector.capacity());// 10
      for (int i = 1; i <= 10; i++) {
         vector.addElement(i);
      }
      System.out.println(vector.capacity());// 10
      vector.addElement("Ashok");
      System.out.println(vector.capacity());// 20
      System.out.println(vector);// [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, Ashok]
   }
}
Vector Class


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