Java.lang.String.indexOf() Method



The java.lang.String.indexOf(String str) method returns the index within this string of the first occurrence of the specified substring. The integer returned is the smallest value k such that: this.startsWith(str, k) is true.


Following is the declaration for java.lang.String.indexOf() method

public int indexOf(String str)


  • str-- This is value of a string.

Return Value

This method returns if the string argument occurs as a substring within this object, then the index of the first character of the first such substring is returned; if it does not occur as a substring, -1 is returned.


  • NA


The following example shows the usage of java.lang.String.indexOf() method.

package com.tutorialspoint;

import java.lang.*;

public class StringDemo {

   public static void main(String[] args) {
   String str1 = "Collections of tutorials at tutorials point";
   // returns index of first character of the substring "tutorials" 
   System.out.println("index =  " + str1.indexOf("tutorials")); 
   // returns -1 as substring "admin" is not located
   System.out.println("index =  " + str1.indexOf("admin"));    

Let us compile and run the above program, this will produce the following result:

index = 15
index = -1