In this tutorials how to swap arraylist elements. We can swap arraylist element by using collections.swap() method and second we can write our own method.
- Swap arraylist element using collections.swap() method.
- Swap arraylist element by our own method.
1. Swap arraylist element using collections.swap() method
syntax
public static void swap(List<?> list, int i, int j) {
}- This method swaps the elements at the given positions in the specified list.
- If the specified positions are equal, invoking this method leaves the list unchanged.
- This method take list in which to swap elements , i the index of one element to be swapped and j the index of the other element to be swapped as paramater .
- It throws IndexOutOfBoundsException – if either i or j is out of range (i < 0 || i >= list.size() || j < 0 || j >= list.size()).
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.
*/
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]2. Swap arraylist element by our own method.
In this method we will use temporary variable for swap two element of arraylist
import java.util.ArrayList;
public class ArrayListSwap {
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);
int i = 1 ;
int j = 2;
//assign element from position i to temporary variable
String element = arr.get(i);
//replace element on position i from position j
arr.set(i, arr.get(j));
//replace element on postion j from temporary variable
arr.set(j, element);
//print arraylist
System.out.println("Arraylist after swap is ="+ arr);
}
}Output :
ArrayList Before Swap is = [c, php, html, java]
Arraylist after swap is =[c, html, php, java]