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Sunday, 10 May 2015

Swap elements of Java ArrayList example

We Swap List element using swap method of    Collections.

import java.util.ArrayList;
import java.util.Collections;

public class SwapElement {


    public static void main(String[] args) {
        ArrayList<String> arr = new ArrayList<String>();
        // add element in arraylist
        arr.add("c");
        arr.add("php");
        arr.add("html");
        arr.add("java");
        // print arraylist
        System.out.println("ArrayList Before Swap is = " + arr);

        /*
         * Swaps the elements at the specified positions in the specified list.
         *  (If the specified positions are equal,
           invoking this method leaves the list unchanged.)
         
          Parameters:
       
        list The list in which to swap elements.
        i the index of one element to be swapped.
        j the index of the other element to be swapped.
      
        Throws:
      
       IndexOutOfBoundsException - if either i or j is out of range (i < 0 || i >= list.size() || j < 0 || j >=
        list.size()).
         */

        Collections.swap(arr, 1, 3);
       
        System.out.println("ArrayList Before Swap is = " + arr);
       
    }
   
   
}


Output:

ArrayList Before Swap is = [c, php, html, java]

ArrayList Before Swap is = [c, java, html, php]



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