Swapping items of a list in Java : Collections.swap() with Example

java.util.Collections.swap() method is a java.util.Collections class method. It swaps elements at the specified positions in given list.

// Swaps elements at positions "i" and "j" in myList.
public static void swap(List mylist, int i, int j)

It throws IndexOutOfBoundsException if either i
or j is out of range.

// Java program to demonstrate working of Collections.swap
import java.util.*;

public class GFG
{
    public static void main(String[] args)
    {
        // Let us create a list with 4 items
        ArrayList<String>  mylist =
                        new ArrayList<String>();
        mylist.add("code");
        mylist.add("practice");
        mylist.add("quiz");
        mylist.add("geeksforgeeks");

        System.out.println("Original List : \n" + mylist);

        // Swap items at indexes 1 and 2
        Collections.swap(mylist, 1, 2);

        System.out.println("\nAfter swap(mylist, 1, 2) : \n"
                           + mylist);

        // Swap items at indexes 1 and 3
        Collections.swap(mylist, 3, 1);

        System.out.println("\nAfter swap(mylist, 3, 1) : \n"
                           + mylist);
    }
}

Output:

Original List : Original List : 
[code, practice, quiz, geeksforgeeks]

After swap(mylist, 1, 2) : 
[code, quiz, practice, geeksforgeeks]

After swap(mylist, 3, 1) : 
[code, geeksforgeeks, practice, quiz]

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