Java MessageDigest getInstance()

🎓 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 MessageDigest getInstance() method in Java programming and how to use it with an example.

1. MessageDigest getInstance() Method Overview

Definition:

The getInstance() method of the MessageDigest class in Java is a static method used to get a MessageDigest object that implements the specified digest algorithm. The purpose of this method is to provide a way to create MessageDigest objects for generating hash values (digests) from input data.

Syntax:

public static MessageDigest getInstance(String algorithm) throws NoSuchAlgorithmException

Parameters:

- algorithm: The name of the hash function to use, e.g., "MD5", "SHA-256".

Key Points:

- The getInstance() method throws NoSuchAlgorithmException if the specified algorithm is not available in the environment.

- Commonly used algorithms are "MD5", "SHA-1", "SHA-256".

- Once the MessageDigest object is created, you can use it to digest input data and obtain the hash value.

- MessageDigest is thread-safe and can be used by multiple threads concurrently.

2. MessageDigest getInstance() Method Example

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

public class MessageDigestExample {

    public static void main(String[] args) {
        try {
            // Get a MessageDigest object for the SHA-256 algorithm
            MessageDigest sha256Digest = MessageDigest.getInstance("SHA-256");

            // Input data to be hashed
            String inputData = "Java MessageDigest Example";

            // Compute the SHA-256 hash value of the input data
            byte[] hashValue = sha256Digest.digest(inputData.getBytes());

            // Print the computed hash value
            System.out.println("Computed Hash Value: " + Arrays.toString(hashValue));
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
    }
}

Output:

Computed Hash Value: [-123, -58, -93, 72, 112, -53, -53, -40, -74, -116, 104, -32, 13, -58, -121, 62, 68, -105, -20, -79, -5, -103, -62, 115, -53, 87, -67, -73, -46, 33, -55, 25]
(Note: The actual output may vary due to the hashing algorithm and input data.)

Explanation:

In this example, we obtained a MessageDigest object implementing the "SHA-256" algorithm using the getInstance() method. We then provided some input data as a string, converted it to bytes, and computed its hash value using the digest() method of the MessageDigest object. The resulting hash value, represented as a byte array, is then printed to the console.

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