The swap() method of java.util.Collections class is used to swap the elements at the specified positions in the specified list. If the specified positions are equal, invoking this method leaves the list unchanged.
Syntax:
public static void swap(List list, int i, int j)
Parameters: This method takes the following argument as a Parameter
- 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.
Exception This method throws IndexOutOfBoundsException, if either i or j is out of range (i = list.size() || j = list.size()).
Example 1:
Java
// Java program to Swap Elements of Java Vector import java.util.Collections;import java.util.Vector; public class GFG { public static void main(String[] args) { // create vector Vector<String> vector = new Vector<String>(); // insert elements in vector vector.add("A"); vector.add("B"); vector.add("C"); vector.add("D"); vector.add("E"); // print original vector System.out.println("Before Swapping = "+vector); // call Collection.swap() method Collections.swap(vector, 0, 4); // print vector after swap two elements System.out.println("After Swapping = "+vector); }} |
Output
[A, B, C, D, E] After swapping [E, B, C, D, A]
Example 2: For IndexOutOfBoundsException
Java
// Java program to demonstrate // swap() method for IndexOutOfBoundsException import java.util.*; public class GFG1 { public static void main(String[] argv) throws Exception { try { // creating object of List<String> List<String> vector = new ArrayList<String>(); // populate the vector vector.add("rohan"); vector.add("manish"); vector.add("simran"); vector.add("ananya"); vector.add("ishika"); // printing the vector before swap System.out.println("Before swap: " + vector); // swap the elements System.out.println("\nTrying to swap elements" + " more than upper bound index "); Collections.swap(vector, 0, 5); // printing the vector after swap System.out.println("After swap: " + vector); } catch (IndexOutOfBoundsException e) { System.out.println("Exception thrown : " + e); } } } |
Output
Before swap: [rohan, manish, simran, ananya, ishika] Trying to swap elements more than upper bound index Exception thrown : java.lang.IndexOutOfBoundsException: Index 5 out of bounds for length 5