Convert ArrayList to Vector in Java

Last Updated : 10 Feb, 2022

There are several ways to convert ArrayList to Vector. We can use a vector constructor for converting ArrayList to vector. We can read ArrayList elements one by one and add them in vector.

Approach 1: (Using Vector Constructor)

Create an ArrayList.
Add elements in ArrayList.
Create a vector and pass the ArrayList in Vector Constructor.

Vector(Collection c): Creates a vector that contains the elements of collection c.

Vector<E> v = new Vector<E>(Collection c);

Example:

Java

// Java program to Convert ArrayList to Vector 

import java.util.ArrayList;
import java.util.Vector;

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

        // create ArrayList
        ArrayList<Integer> ArrList = new ArrayList<Integer>();

        // add elements in ArrayList
        ArrList.add(10);
        ArrList.add(20);
        ArrList.add(30);
        ArrList.add(40);
        ArrList.add(50);

        // display ArrayList
        System.out.println(" ArrayList : " + ArrList);

        // create vector and pass the ArrayList in vector
        // constructor
        Vector<Integer> vector = new Vector<Integer>(ArrList);

        // print vector
        System.out.println(" Vector : " + vector);
    }
}

Output

 ArrayList : [10, 20, 30, 40, 50]
 Vector : [10, 20, 30, 40, 50]

Approach 2: (Using for loop)

Create a ArrayList.
Add some values in ArrayList.
Create an Vector.
Execute a loop.
Traverse each element of ArrayList from the left side to the right side.
Add the ArrayList elements in Vector.

Example:

Java

// Java program to Convert ArrayList to Vector 

import java.util.Vector;
import java.util.ArrayList;
public class GFG {
    public static void main(String[] args)
    {
        // Create a ArrayList that contain strings
        ArrayList<String> Arrlist = new ArrayList<String>();

        // add values in ArrayList
        Arrlist.add("A");
        Arrlist.add("B");
        Arrlist.add("C");
        Arrlist.add("D");
        Arrlist.add("E");

        // Display the ArrayList
        System.out.println(" ArrayList :  " + Arrlist);

        // create a vector
        Vector<String> v = new Vector<String>();

        // Convert ArrayList to Vector

        // get the size to ArrayList
        int n = Arrlist.size();

        // execute for loop from 0 to n
        for (int i = 0; i < n; i++) {
          
            // get the elements from ArrayList
            // and add the arrayList elements in vector
            v.add(Arrlist.get(i));
        }

        // Display Vector
        System.out.println("\n vector : " + v);
    }
}

Output

 ArrayList :  [A, B, C, D, E]

 vector : [A, B, C, D, E]

Approach 3: (Using addAll() method)

This method is used to append all the elements from the collection passed as a parameter to this function to the end of a vector keeping in mind the order of return by the collection’s iterator.

Syntax:

boolean addAll(Collection C)

Parameters: The method accepts a mandatory parameter C which is a collection of ArrayList. It is the collection whose elements are needed to be appended at the end of the vector.

Return Value: The method returns True if at least one action of append is performed, else False.

Example:

Java

// Java program to Convert ArrayList to Vector 

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

class GFG {
    public static void main(String[] args)
    {
        ArrayList<String> listStrings = new ArrayList<>();

        listStrings.add("Geeks");
        listStrings.add("for");
        listStrings.add("Geeks");

        // create empty vector object
        Vector<String> vStrings = new Vector<>();

        // use the addAll method
        vStrings.addAll(listStrings);

        System.out.println("Vector contains: " + vStrings);
    }
}