Understanding the Key Differences Between Immutable and Singleton Classes in Java

Overview

In Java development, it’s essential to understand the difference between key design patterns and class structures like Immutable Classes and Singleton Classes. These concepts serve different purposes in application design and architecture, affecting object creation, mutability, thread safety, and overall performance. This article dives into a comprehensive comparison of immutable and singleton classes, highlighting their characteristics and use cases.

Table of Contents

1. What is an Immutable Class?
2. What is a Singleton Class?
3. Key Differences Between Immutable and Singleton Classes
4. When to Use Immutable Classes?
5. When to Use Singleton Classes?
6. Code Examples

• Immutable Class Example
• Singleton Class Example

What is an Immutable Class?

An immutable class is a class whose objects cannot be modified once they are created. This means all fields of the class are final, and no setter methods are provided. Immutable objects are often simpler to understand and work with, as their state remains constant throughout their lifetime.

Common examples of immutable classes in Java are String, Integer, and LocalDateTime. Once an instance of these…