Java String - indexOf() Method

The java.lang.String.indexOf() method is used to find out the index number for first occurrence of specified substring in the given string.

Syntax

public int indexOf(String str)

Parameters

str specify the substring to search for.

Return Value

Returns the index number for first occurrence of specified substring. Returns -1 if there is no such occurrence.

Exception

NA.

Example:

Here, the indexOf() method is used to find out the index number for first occurrence of specified substring in the given string.

import java.lang.*;

public class MyClass {
  public static void main(String[] args) {
    String MyString = "Java is a programming language. Learning Java is fun.";
    
    //index number of first occurrence 
    //of "is" in the given string
    System.out.println(MyString.indexOf("is")); 
  }
}

The output of the above code will be:

❮ Java.lang - String