List indexOf() Method in Java with Examples Last Updated : 29 Nov, 2024 Comments Improve Suggest changes Like Article Like Report This method returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element. Example: Java // Java Program to Implement List // indexOf() Method import java.util.*; class GFG { public static void main (String[] args) { // List Created List<String> l = new ArrayList<String>(); // Adding Elements l.add("Geeks"); l.add("for Geeks"); l.add("GFG"); // Index Of System.out.println("Index of GFG is " + l.indexOf("GFG")); } } OutputIndex of GFG is 2 Syntax of Methodpublic int indexOf(Object o)Parameters: This function has a single parameter, i.e, the element to be searched in the list. Returns: This method returns the index of first occurrence of the given element in the list and returns "-1" if element is not in the list. Example of List indexOf() MethodBelow programs show the implementation of this method. Program 1: Java // Java code to show the implementation of // indexOf method in list interface import java.util.*; public class GfG { public static void main(String[] args) { // Initializing a list of type Linkedlist List<Integer> l = new LinkedList<>(); // Adding elements in List l.add(1); l.add(3); l.add(5); l.add(7); System.out.println(l); // Index Of System.out.println(l.indexOf(5)); } } Output[1, 3, 5, 7] 2 Program 2: Below is the code to show implementation of list.hashCode() using Linkedlist. Java // Java code to show the implementation of // indexOf method in list interface import java.util.*; public class GfG { public static void main(String[] args) { // Initializing a list of type Linkedlist List<String> l = new LinkedList<>(); l.add("10"); l.add("15"); l.add("20"); System.out.println(l); System.out.println(l.indexOf("20")); } } Output[10, 15, 20] 2 Reference: Oracle Docs Comment More infoAdvertise with us B barykrg Follow Improve Article Tags : Java Java-Collections Java - util package Java-Functions java-list +1 More Practice Tags : JavaJava-Collections Explore BasicsIntroduction to Java4 min readJava Programming Basics9 min readJava Methods7 min readAccess Modifiers in Java6 min readArrays in Java9 min readJava Strings8 min readRegular Expressions in Java7 min readOOPs & InterfacesClasses and Objects in Java10 min readJava Constructors10 min readJava OOP(Object Oriented Programming) Concepts10 min readJava Packages7 min readJava Interface11 min readCollectionsCollections in Java12 min readCollections Class in Java13 min readCollection Interface in Java6 min readIterator in Java5 min readJava Comparator Interface6 min readException HandlingJava Exception Handling8 min readJava Try Catch Block4 min readJava final, finally and finalize4 min readChained Exceptions in Java3 min readNull Pointer Exception in Java5 min readException Handling with Method Overriding in Java4 min readJava AdvancedJava Multithreading Tutorial15+ min readSynchronization in Java10 min readFile Handling in Java5 min readJava Method References9 min readJava 8 Stream Tutorial15+ min readJava Networking15+ min readJDBC Tutorial12 min readJava Memory Management4 min readGarbage Collection in Java6 min readMemory Leaks in Java3 min readPractice JavaJava Interview Questions and Answers15+ min readJava Programs - Java Programming Examples8 min readJava Exercises - Basic to Advanced Java Practice Programs with Solutions7 min readJava Quiz | Level Up Your Java Skills1 min readTop 50 Java Project Ideas For Beginners and Advanced [Update 2025]15+ min read Like