Java ArrayList indexOf example

ArrayList‘s indexOf method is used to find out first index of object in arraylist.

indexOf method takes object as argument and returns first occurrence of specified element.

Methods:

public int indexOf(Object o)
returns index of first occurrence of element in the ArrayList.

indexOf method return -1 if object is not present in the ArrayList

ArrayList indexOf Example:

import java.util.ArrayList;

import java.util.HashSet;

import java.util.LinkedHashSet;

import java.util.*;

class IndexOfArrayListMain {

* @author : Arpit Mandliya

public static void main(String[] args) {

ArrayList employeeNameList = new ArrayList();

employeeNameList.add("John");

employeeNameList.add("Ankit");

employeeNameList.add("Rohan");

employeeNameList.add("Amit");

System.out.println("Index of Ankit: "+employeeNameList.indexOf("Ankit"));

System.out.println("*******************************");

System.out.println("Index of John: "+employeeNameList.indexOf("John"));

System.out.println("*******************************");

// Arpit is not present in the list

System.out.println("Index of Arpit: "+employeeNameList.indexOf("Arpit"));

}

When you run above program, you will get below output

Index of Ankit: 1

*******************************

Index of John: 0

*******************************

Index of Arpit: -1

[Fixed] java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList

Create ArrayList of Objects in Java

How to remove element from Arraylist in java while iterating

How to Deep Copy Arraylist in Java

Initialize ArrayList with values in Java

PriorityQueue in Java 8

Author

java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList

Core java Error Java Collections

22 February

[Fixed] java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList

Table of ContentsReason for java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayListFixes for java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayListUse ArrayList’s constructorAssign Arrays.asList() to List reference rather than ArrayList In this post, we will see how to fix java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList. ClassCastException is runtime exception which indicate that code has tried to […]

Core java Java Collections

25 January

Create ArrayList of Objects in Java

Table of ContentsUsing the add() method to create ArrayList of objects in javaUsing parameterized constructor to create ArrayList of objects in javaUsing addAll() method to create ArrayList of objects in javaConclusion In this tutorial, we will learn how to create ArrayList of objects in Java. We will create a Book class with different properties and […]

Java Collections

10 September

How to remove element from Arraylist in java while iterating

Table of ContentsIntroductionUsing Collection’s removeIf() methodUsing ListIterator classUsing removeAll() methodUsing Java 8 Stream to filter List itemsConclusion Introduction In this tutorial, you will learn how to remove element from Arraylist in java while iterating using different implementations provided by Java. It is necessary to understand the right way to remove items from a List because […]

Java Collections

30 June

Print HashMap in Java

Table of ContentsPrint from the HashMap ReferencePrint HashMap using foreach method with keyset()Print HashMap using Consumer with entrySet()Print HashMap using Arrays’s asList() methodPrint HashMap using Collections’s singletonList()Print HashMap using getkey() and getValue with entrySet()Print HashMap using BiConsumerPrint HashMap using IteratorPrint HashMap using custom ObjectsConclusion In this article, we will see how to print HashMap in […]

Java Collections

26 June

Print LinkedList in java

Table of ContentsJava inbuilt LinkedListPrint LinkedList using a for loopPrint LinkedList using Enhanced for loopPrint LinkedList using streamsPrint LinkedList using toString() methodPrint LinkedList using IteratorPrint LinkedList using custom objectsCustom singly LinkedListHow to print a custom singly LinkedListConclusion Java inbuilt LinkedList Java inbuilt LinkedList class uses doubly linked list as internal data structure to store its […]

Conversion Java Collections

12 May

Java Set to Array

Table of Contents1. Using Java 8’s Stream2. Using toArray()3. Using toArray(IntFunction) [Java 11]4. Using System.arraycopy()5. Using Arrays.copyOf6. Using simple iteration7. Using Guava library7.1 Using FluentIterable7.2 Using Iterables In this post, we will learn java set to array conversion. There are many ways to convert set to an array. 1. Using Java 8’s Stream If you […]

Java ArrayList indexOf example

Methods:

ArrayList indexOf Example:

You may also like:

[Fixed] java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList

Create ArrayList of Objects in Java

How to remove element from Arraylist in java while iterating

Print HashMap in Java

Print LinkedList in java

Java Set to Array

Print ArrayList in Java

How to Deep Copy Arraylist in Java

Initialize ArrayList with values in Java

PriorityQueue in Java 8

Author

Related Posts

[Fixed] java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList

Create ArrayList of Objects in Java

How to remove element from Arraylist in java while iterating

Print HashMap in Java

Print LinkedList in java

Java Set to Array

Leave a Reply Cancel reply

Categories

Popular Posts

Let’s be Friends

Methods:

ArrayList indexOf Example:

You may also like:

Share this

Author

Related Posts

[Fixed] java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList

Create ArrayList of Objects in Java

How to remove element from Arraylist in java while iterating

Print HashMap in Java

Print LinkedList in java

Java Set to Array

Leave a Reply Cancel reply

Subscribe to our newletter

Let’s be Friends