Java – String indexOf() Method

Description:

This method has following different variants:

  • public int indexOf(int ch): Returns the index within this string of the first occurrence of the specified character or -1 if the character does not occur.

  • public int indexOf(int ch, int fromIndex): Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index or -1 if the character does not occur.

  • int indexOf(String str): Returns the index within this string of the first occurrence of the specified substring. If it does not occur as a substring, -1 is returned.

  • int indexOf(String str, int fromIndex): Returns the index within this string of the first occurrence of the specified substring, starting at the specified index. If it does not occur, -1 is returned.

Syntax:

Here is the syntax of this method:

public int indexOf(int ch )

or

public int indexOf(int ch, int fromIndex)

or

int indexOf(String str)

or

int indexOf(String str, int fromIndex)

Parameters:

Here is the detail of parameters:

  • ch — a character.
  • fromIndex — the index to start the search from.
  • str — a string.

Return Value:

See the description.

Example:

import java.io.*;

public class Test {

   public static void main(String args[]) {
      String Str = new String("Welcome to www.dineshonjava.com");
      String SubStr1 = new String("Tutorials");
      String SubStr2 = new String("Sutorials");

      System.out.print("Found Index :" );
      System.out.println(Str.indexOf( 'o' ));
      System.out.print("Found Index :" );
      System.out.println(Str.indexOf( 'o', 5 ));
      System.out.print("Found Index :" );
      System.out.println( Str.indexOf( SubStr1 ));
      System.out.print("Found Index :" );
      System.out.println( Str.indexOf( SubStr1, 15 ));
      System.out.print("Found Index :" );
      System.out.println(Str.indexOf( SubStr2 ));
   }
}

This produces following result:

output:
Found Index :4
Found Index :9
Found Index :-1
Found Index :-1
Found Index :-1
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Dinesh Rajput

Dinesh Rajput is the chief editor of a website Dineshonjava, a technical blog dedicated to the Spring and Java technologies. It has a series of articles related to Java technologies. Dinesh has been a Spring enthusiast since 2008 and is a Pivotal Certified Spring Professional, an author of a book Spring 5 Design Pattern, and a blogger. He has more than 10 years of experience with different aspects of Spring and Java design and development. His core expertise lies in the latest version of Spring Framework, Spring Boot, Spring Security, creating REST APIs, Microservice Architecture, Reactive Pattern, Spring AOP, Design Patterns, Struts, Hibernate, Web Services, Spring Batch, Cassandra, MongoDB, and Web Application Design and Architecture. He is currently working as a technology manager at a leading product and web development company. He worked as a developer and tech lead at the Bennett, Coleman & Co. Ltd and was the first developer in his previous company, Paytm. Dinesh is passionate about the latest Java technologies and loves to write technical blogs related to it. He is a very active member of the Java and Spring community on different forums. When it comes to the Spring Framework and Java, Dinesh tops the list!

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