Copy Elements of One Java Vector to Another Vector in Java

Vector is similar to arrays but is growable also, or we can say no fixed size is required. Previously vector was a part of legacy classes but now it is part of Collections. It also implements a List interface, so we can use any method of list interface on vectors also.

Syntax :

Vector<Integer> gfg=new Vector<>();

Ways To copy elements of one vector to another:

1. Passing in the constructor
2. Adding one by one using add() method

Method 1: Passing in the constructor 

• In this approach, we will simply pass the one Vector into the other Vector’s constructor.
• By using this approach if we change in first vector values then it will not change the values of the second vector.
• This is the easiest way of duplicating the vector values.

In the below program we will,

• First, create one Vector of integers and add elements to it using add() method.
• After that, we will pass the first vector into the constructor of the second.
• Now we will change one value vector and will check in another vector also to verify whether changing one vector value does not affect another vector.

Java

// Java Program for copying one Vector to another
// by passing in the constructor

import java.io.*;
import java.util.Vector;

class GFG {
    public static void main (String[] args) {

    // creation of Vector of Integers
    Vector<Integer> gfg=new Vector<>();

    // adding elements to  first Vector
    gfg.add(11);
    gfg.add(22);
    gfg.add(24);
    gfg.add(39);

    // passing in the constructor
    Vector<Integer> gfg2=new Vector<>(gfg);


    //Iterating over  second Vector
    System.out.println("-----Iterating over the second Vector----");

    for(Integer value: gfg2){
    System.out.println(value);
    }

    // here we changed the third element to 23
    // we changed in the second vector and you can
    // here we will not see the same change in the first
    gfg2.set(2,23);

    System.out.println("third element of first vector ="+gfg.get(2));
    System.out.println("third element of second vector ="+gfg2.get(2));

    }
}

Output

-----Iterating over the second Vector----
11
22
24
39
third element of first vector =24
third element of second vector =23

Method 2: Adding one by one using add() method 

• In this approach, we will iterate over each element of  Vector and add that element in the second Vector.
• Here if you change the first Vector element then it will not change the elements of the second Vector.
• It is not the best approach but it’s a simple iteration process.

In the below program we will first create one Vector of integers and add elements to it after that we will iterate on that vector and add the element at each iteration to the other vector.

Java

// Java Program for  copying one Vector to another
// by adding elements one by one using add() method

import java.io.*;
import java.util.Vector;

class GFG {
    public static void main (String[] args) {

    // creation of Vector of Integers
    Vector<Integer> gfg=new Vector<>();

    // adding elements to  first Vector
    gfg.add(50);
    gfg.add(24);
    gfg.add(95);
    gfg.add(31);

    Vector<Integer> gfg2=new Vector<>();

    // adding element to the second Vector
    // by iterating over one by one
    for(Integer value: gfg){
    gfg2.add(value);
    }

    // Iterating over  second Vector
    System.out.println("-----Iterating over the second Vector----");

    for(Integer value :gfg2)
    {
      System.out.println(value);
    }

    // here we changed the third element to 23
    // we changed in second Vector
    // here we will not see the same change in the first
    gfg2.set(2,23);

    System.out.println("third element of first Vector ="+gfg.get(2));
    System.out.println("third element of second Vector ="+gfg2.get(2));

    }
}

Output

-----Iterating over the second Vector----
50
24
95
31
third element of first Vector =95
third element of second Vector =23