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Convert ArrayList to Vector in Java
  • Last Updated : 17 Dec, 2020

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 Vetor 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 AffayList
        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);
    }
}
Output
Vector contains: [Geeks, for, Geeks]

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