java.util.Collections.swap(List<?>, int, int) Method

---

Description

The swap(List<?>, int, int) method is used to swap the elements at the specified positions in the specified list.

Declaration

Following is the declaration for java.util.Collections.swap() method.

public static void swap(List<?> list,int i,int j)

Parameters

• list − The list in which to the swap elements.

• i − The index of one element to be swapped.

• j − The index of the other element to be swapped.

Return Value

NA

Exception

IndexOutOfBoundsException − This is thrown if either i or j is out of range (i < 0 || i >= list.size() || j < 0 || j >= list.size()).

Example

The following example shows the usage of java.util.Collections.swap()

package com.tutorialspoint;

import java.util.*;

public class CollectionsDemo {
   public static void main(String[] args) {
      
      // create vector object 
      Vector<String> vector = new Vector<String>();

      // populate the vector
      vector.add("1");
      vector.add("2");
      vector.add("3");
      vector.add("4");
      vector.add("5");

      System.out.println("Before swap: "+vector);

      // swap the elements
      Collections.swap(vector, 0, 4);

      System.out.println("After swap: "+vector);
   }
}   

Let us compile and run the above program, this will produce the following result.

Before swap: [1, 2, 3, 4, 5]
After swap: [5, 2, 3, 4, 1]