Table of Contents

Java indexOf() method

The indexOf() method is used to find the position of a character or substring within a string. It is a part of the String class and comes in several variations. The Java indexOf() method returns the index of the given character value or the substring. If it is not found, it returns -1. The index counter starts from zero.

Method signatures

The signature of indexOf methods are as follows:

int indexOf(int ch): This method returns the index position for the given char value.
int indexOf(int ch, int fromIndex) : This method returns the index position for the given char value and from index
int indexOf(String Substring) : This method returns the index position for the given substring
int indexOf(String substring, intIndex) : This method returns the index position for the given substring and from index

Example

A sample program to demonstrate the use of the indexOf() method is as follows:

package com.testingdocs.stringmethods;

public class IndexOfMethodDemo {

 public static void main(String[] args) {

 String str= "This is a sample sentence example.";
 
 // index of character
 int index_of_s=str.indexOf('s'); 
 System.out.println(index_of_s);

 // index of word or substring
 int index_of_is1 = str.indexOf("is"); 
 System.out.println(index_of_is1);
 
 
 int index_of_sample = str.indexOf("sample"); 
 System.out.println(index_of_sample);
 }
}