Java String intern() Method

🎓 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

The String.intern() method in Java is used to return a canonical representation of the string. This guide will cover the method's usage, explain how it works, and provide examples to demonstrate its functionality.

Table of Contents

1. Introduction
2. intern Method Syntax
3. Examples
   • Interning a String
   • Comparing Interned Strings
   • Benefits of String Interning
4. Conclusion

Introduction

The String.intern() method is a member of the String class in Java. It allows you to ensure that all identical strings are represented by the same String object, which can help save memory and improve performance in some cases.

intern Method Syntax

The syntax for the intern method is as follows:

public native String intern();

Examples

Interning a String

The intern method can be used to return a canonical representation of a string.

Example

public class InternExample {
    public static void main(String[] args) {
        String str1 = new String("Hello");
        String str2 = new String("Hello");

        String internedStr1 = str1.intern();
        String internedStr2 = str2.intern();

        System.out.println("str1 == str2: " + (str1 == str2)); // false
        System.out.println("internedStr1 == internedStr2: " + (internedStr1 == internedStr2)); // true
    }
}

Output:

str1 == str2: false
internedStr1 == internedStr2: true

Comparing Interned Strings

Interning strings ensures that identical strings share the same memory reference, making it easy to compare strings using the == operator.

Example

public class InternExample {
    public static void main(String[] args) {
        String str1 = "Java";
        String str2 = new String("Java");

        String internedStr2 = str2.intern();

        System.out.println("str1 == str2: " + (str1 == str2)); // false
        System.out.println("str1 == internedStr2: " + (str1 == internedStr2)); // true
    }
}

Output:

str1 == str2: false
str1 == internedStr2: true

Benefits of String Interning

String interning can be beneficial in situations where you have many identical strings, as it reduces memory usage by ensuring that only one instance of each unique string is stored.

Example

public class InternExample {
    public static void main(String[] args) {
        String[] strings = new String[1000];

        for (int i = 0; i < strings.length; i++) {
            strings[i] = ("String" + i % 10).intern();
        }

        System.out.println("Memory saved by interning strings.");
    }
}

Output:

Memory saved by interning strings.

Conclusion

The String.intern() method in Java is used for optimizing memory usage and performance by ensuring that identical strings are represented by the same String object. By understanding how to use this method, you can efficiently manage strings in your Java applications. Whether you are interning strings, comparing interned strings, or taking advantage of the benefits of string interning, the intern method provides a reliable solution for these tasks.

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