Replace an Element From ArrayList using Java ListIterator Last Updated : 03 Apr, 2023 Comments Improve Suggest changes Like Article Like Report To replace an element from an ArrayList, the set() method of ListIterator interface can be used. set() method of ListIterator replaces the last element which is returned by the next() or previous() methods, along with the given element. Two ways of replacing the elements using ListIterator shown below are: Replacing First elementReplacing Last element Replacing First element: Approach Creating an ArrayListArrayList<Integer> list = new ArrayList<Integer>(); list.add(9); list.add(11); list.add(12); list.add(13); list.add(14); list.add(15):Suppose we need to replace the first element of the list which is 9 with 10. First, we will use ListIterator and return the next element in the List with next() method.ListIterator<Integer> iterator = list.listIterator(); iterator.next();Now, using set() method replace the element in the List. Here we will be replacing first element of the iterator which can be replaced with any specified value ( in our case we need to replace it with 10 ).iterator.set(10); Java // Java program to replace an element // from ArrayList using Java ListIterator import java.util.ArrayList; import java.util.ListIterator; class GFG { public static void main(String[] args) { ArrayList<Integer> list = new ArrayList<Integer>(); list.add(9); list.add(11); list.add(12); list.add(13); list.add(14); list.add(15); System.out.println("Before Replacing..."); // Printing the original list for (int i : list) { System.out.println(i); } ListIterator<Integer> iterator = list.listIterator(); // Replacing the first element iterator.next(); iterator.set(10); System.out.println("After replacing..."); // Printing the list after replacement for (int i : list) { System.out.println(i); } } } OutputBefore Replacing... 9 11 12 13 14 15 After replacing... 10 11 12 13 14 15 Time Complexity: O(n) Auxiliary Space: O(1) As constant extra space is used. Replacing the last element: Approach Using the same above method, any element of the ArrayList at any position, can be replaced with any value.Creating an ArrayList of names and add a few names to it -ArrayList<String> name = new ArrayList<>(); name.add("Yash"); name.add("Akash"); name.add("Amar"); name.add("Abhishek"); name.add("Rajnikanth");Let us assume that we need to replace "Rajnikanth" with "Mohit".Now, using a ListIterator, we will iterate to the last element of the list and then replace it -ListIterator<String> iterator = name.listIterator(); while(iterator.hasNext()) { iterator.next(); } iterator.set("Mohit"); Java // java program to replace an element // from ArrayList using Java ListIterator import java.util.ArrayList; import java.util.ListIterator; class GFG { public static void main(String[] args) { ArrayList<String> name = new ArrayList<>(); name.add("Yash"); name.add("Akash"); name.add("Amar"); name.add("Abhishek"); name.add("Rajnikanth"); ListIterator<String> iterator = name.listIterator(); System.out.println("Before Replacing..."); // Printing the original list while (iterator.hasNext()) { System.out.print(iterator.next()+" "); } // Simce the iterator was on last element // so the set function used here will replace // the last element iterator.set("Mohit"); System.out.println(); System.out.println("After Replacing..."); for (String n : name) { System.out.print(n+" "); } } } OutputBefore Replacing... Yash Akash Amar Abhishek Rajnikanth After Replacing... Yash Akash Amar Abhishek Mohit Time Complexity: O(n) Auxiliary Space: O(1) As constant extra space is used. Comment More infoAdvertise with us Next Article Replace an Element From ArrayList using Java ListIterator V vermayash16 Follow Improve Article Tags : Java Java Programs Java-Collections Java-ArrayList Java-Iterator +1 More Practice Tags : JavaJava-Collections Similar Reads Java Program to Remove an Element from ArrayList using ListIterator ListIterator.remove() method removes the last element from the list that was returned by next() or previous() cursor positions. It can be called only once per call to next or previous. It can be made only if the operation — add(E) has not called after the last call to next or previous. Internal work 4 min read Java Program to Add an Element to ArrayList using ListIterator In this article, we will learn how to add an element to ArrayList using ListIterator. 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