Understanding Vectors in Java: A Comprehensive Guide

Vectors

These are also Collection of elements those are object data type For Using Vectors we have to import java.util package These are also Called as dynamic Array of object data type .

But Always Remember vectors doesn’t support primitives data types like int, float, char etc. For Creating a Vector, Vector Class will be used which is reside in java’s utility package

Vector implements a dynamic array. It is similar to ArrayList, but with two differences ?

• Vector is synchronized.

• Vector contains many legacy methods that are not part of the collections framework.

Vector proves to be very useful if you don't know the size of the array in advance or you just need one that can change sizes over the lifetime of a program.

Three ways to create vector class object:

Method 1:

Vector vect = new Vector();

It creates an empty Vector with the default initial capacity of 10. It means the Vector will be re-sized when the 11th elements need to be inserted into the Vector. Note: By default, vector doubles its size. i.e., In this case, the Vector size would remain 10 till 10 insertions and once we try to insert the 11th element It would become 20 (double of default capacity 10).

Method 2:
Syntax:

Vector object= new Vector(int initialCapacity)

Vector vec = new Vector(3);

It will create a Vector of the initial capacity of 3.

Method 3:
Syntax:

Vector object= new vector(int initialcapacity, capacityIncrement)

Example:

Vector vec= new Vector(4, 6)

Here we have provided two arguments. The initial capacity is 4 and capacityIncrement is 6. It means upon insertion of 5th element the size would be 10 (4+6) and on 11th insertion it would be 16(10+6).

Complete Example of Vector in Java:

/*
  Simple Java Vector Example
  This Java Example shows how to create an object of Java Vector. It also
  shows how to add elements to Vector and how get the same from Vector.
*/

import java.util.Iterator;
import java.util.Vector;

public class SimpleVectorExample {

  public static void main(String[] args) {

    //create a Vector object
    Vector v = new Vector();

    /*
       Add elements to Vector using
       boolean add(Object o) method. It returns true as a general behavior
       of Collection.add method. The specified object is appended at the end
       of the Vector.
    */
    v.add("1");
    v.add("2");
    v.add("3");

    /*
      Use get method of Java Vector class to display elements of Vector.
      Object get(int index) returns an element at the specified index in
      the Vector
    */
    System.out.println("Getting elements of Vector");
    System.out.println(v.get(0));
    System.out.println(v.get(1));
    System.out.println(v.get(2));
  }
}
 

Output

Getting elements of Vector
1
2
3
Press any key to continue . . .
 

Complete Example of Vector in Java:

 import java.util.*;

public class VectorExample {

   public static void main(String args[]) {
      /* Vector of initial capacity(size) of 2 */
      Vector vec = new Vector(2);

      /* Adding elements to a vector*/
      vec.addElement("Apple");
      vec.addElement("Orange");
      vec.addElement("Mango");
      vec.addElement("Fig");

      /* check size and capacityIncrement*/
      System.out.println("Size is: "+vec.size());
      System.out.println("Default capacity increment is: "+vec.capacity());

      vec.addElement("fruit1");
      vec.addElement("fruit2");
      vec.addElement("fruit3");

      /*size and capacityIncrement after two insertions*/
      System.out.println("Size after addition: "+vec.size());
      System.out.println("Capacity after increment is: "+vec.capacity());

      /*Display Vector elements*/
      Enumeration en = vec.elements();
      System.out.println("\nElements are:");
      while(en.hasMoreElements())
         System.out.print(en.nextElement() + " ");
   }
}
 

Output

 Size is: 4
Default capacity increment is: 4
Size after addition: 7
Capacity after increment is: 8

Elements are:
Apple Orange Mango Fig fruit1 fruit2 fruit3 Press any key to continue . . .
 

Difference between ArrayList and Vector

Following is the list of constructors provided by the vector class.

Apart from the methods inherited from its parent classes, Vector defines the following methods ?