Java String substring() example

🎓 Top 15 Udemy Courses (80-90% Discount): My Udemy Courses - Ramesh Fadatare — All my Udemy courses are real-time and project oriented courses.

▶️ Subscribe to My YouTube Channel (178K+ subscribers): Java Guides on YouTube

▶️ For AI, ChatGPT, Web, Tech, and Generative AI, subscribe to another channel: Ramesh Fadatare on YouTube

In this guide, you will learn about the String substring() method in Java programming and how to use it with an example.

1. String substring() Method Overview

Definition:

The substring() method of Java's String class returns a new string that is a substring of the given string.

Syntax:

1. str.substring(int beginIndex)
2. str.substring(int beginIndex, int endIndex)

Parameters:

- beginIndex: the starting index, inclusive.

- endIndex: the ending index, exclusive.

Key Points:

- The substring starts with the character at the specified beginIndex and extends to the end of the string or up to endIndex - 1 if the second argument is given.

- If beginIndex equals endIndex, the method returns an empty string.

- Indexes are 0-based.

- Throws IndexOutOfBoundsException if the beginIndex is negative, or endIndex is larger than the length of the string, or beginIndex is larger than endIndex.

2. String substring() Method Example

public class SubstringExample {
    public static void main(String[] args) {
        String sample = "JavaProgrammingIsFun";

        // Extracting substring from index 4 to the end
        String sub1 = sample.substring(4);
        System.out.println("Substring from index 4: " + sub1);

        // Extracting substring from index 4 to 15 (exclusive)
        String sub2 = sample.substring(4, 15);
        System.out.println("Substring from index 4 to 15: " + sub2);

        // Using identical beginIndex and endIndex
        String sub3 = sample.substring(5, 5);
        System.out.println("Substring from index 5 to 5: '" + sub3 + "'");
    }
}

Output:

Substring from index 4: ProgrammingIsFun
Substring from index 4 to 15: Programming
Substring from index 5 to 5: ''

Explanation:

In the example:

1. The first usage of substring() extracts the substring starting from index 4 to the end of the string, resulting in "ProgrammingIsFun".

2. The second usage extracts a substring starting from index 4 and ending at index 15 (exclusive). This results in the substring "Programming".

3. The third usage demonstrates how using identical values for beginIndex and endIndex yields an empty string.

Related Java String Class method examples

• Java String charAt() example
• Java String concat() example
• Java String contains() example
• Java String endsWith() example
• Java String equals() example
• Java String equalsIgnoreCase() example
• Java String getBytes() example
• Java String indexOf() example
• Java String isEmpty() example
• Java String lastIndexOf() example
• Java String length() example
• Java String replace() example
• Java String split() example
• Java String startsWith() example
• Java String substring() example
• Java String toLowerCase() example
• Java String toUpperCase() example
• Java String trim() example
• Java String valueOf() example

My Top and Bestseller Udemy Courses. The sale is going on with a 70 - 80% discount. The discount coupon has been added to each course below:

Build REST APIs with Spring Boot 4, Spring Security 7, and JWT

🆕 High-Demand 80–90% OFF

[NEW] Learn Apache Maven with IntelliJ IDEA and Java 25

🆕 High-Demand 80–90% OFF

ChatGPT + Generative AI + Prompt Engineering for Beginners

🚀 Trending Now 80–90% OFF

Spring 7 and Spring Boot 4 for Beginners (Includes 8 Projects)

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Building Real-Time REST APIs with Spring Boot - Blog App

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Building Microservices with Spring Boot and Spring Cloud

🌟 Top Rated 80–90% OFF
Available in Udemy for Business

Java Full-Stack Developer Course with Spring Boot and React JS

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Build 5 Spring Boot Projects with Java: Line-by-Line Coding

🌟 Top Rated 80–90% OFF

Testing Spring Boot Application with JUnit and Mockito

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Spring Boot Thymeleaf Real-Time Web Application - Blog App

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Master Spring Data JPA with Hibernate

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Spring Boot + Apache Kafka Course - The Practical Guide

🎓 Student Favorite 80–90% OFF
Available in Udemy for Business

Java Testing: Mastering JUnit 5 Framework

🆕 New 80–90% OFF

Reactive Programming in Java: Spring WebFlux and Testing

🌟 Top Rated 80–90% OFF

Spring Boot + RabbitMQ Course - The Practical Guide

🌟 Top Rated 80–90% OFF
Available in Udemy for Business

Functional Programming in Java (Includes Java Collections)

🎓 Student Favorite 80–90% OFF

ChatGPT for Java Developers: Boost Your Productivity with AI

🚀 Trending Now 80–90% OFF