To replace an element in Java ArrayList, set() method of java.util. An ArrayList class can be used. The set() method takes two parameters-the indexes of the element which has to be replaced and the new element. The index of an ArrayList is zero-based. So, to replace the first element, 0 should be the index passed as a parameter.
Declaration:
public Object set(int index, Object element)
Return Value: The element which is at the specified index
Exception Throws: IndexOutOfBoundsExceptionÂ
This occurs when the index is out of range.
index < 0 or index >= size()
Implementation:
Here we will be proposing out 2 examples wherein one of them we will be setting the index within bound and in the other, we will be setting the index out of bounds.Â
Example 1: Where Index is Within BoundÂ
Java
// Java program to demonstrate set() Method of ArrayList// Where Index is Within BoundÂ
// Importing required classesimport java.io.*;import java.util.*;Â
// Main classclass GFG {Â
  // Main driver method  public static void main(String[] args) {Â
    // Try block to check for exceptions    try {Â
      // Creating an object of Arraylist class      ArrayList<String> list = new ArrayList<>();Â
Â
      // Adding elements to the List      // using add() methodÂ
      // Custom input elements      list.add("A");      list.add("B");      list.add("C");      list.add("D");Â
      // Print all the elements added in the above object      System.out.println(list);Â
      // 2 is the index of the element "C".      //"C" will be replaced by "E"      list.set(2, "E");Â
      // Printing the newly updated List      System.out.println(list);Â
    }Â
    // Catch block to handle the exceptions    catch (Exception e) {Â
      // Display the exception on the console      System.out.println(e);    }  }} |
[A, B, C, D] [A, B, E, D]
 Example 2: Where Index is Out of Bound
Java
// Java program to demonstrate set() Method of ArrayList// Where Index is Out of BoundÂ
// Importing required classesimport java.io.*;import java.util.*;Â
// Main classclass GFG {Â
  // Main driver method  public static void main(String[] args) {Â
    // Try block to check for exceptions    try {Â
      // Creating an object of Arraylist class      ArrayList<String> list = new ArrayList<>();Â
Â
      // Adding elements to the List      // using add() methodÂ
      // Custom input elements      list.add("A");      list.add("B");å      list.add("C");      list.add("D");Â
      // Print all the elements added in the above object      System.out.println(list);Â
             // Settijg the element at the 6 th index which      // does not exist in our input list object      list.set(6);         // Printing the newly updated List      System.out.println(list);    }Â
    // Catch block to handle the exceptions    catch (Exception e) {Â
      // Display the exception on the console      System.out.println(e);    }  }} |
Output:
