Singleton Pattern in Object-Oriented Programming

Singleton Pattern in Object-Oriented Programming

📘 Overview The Singleton pattern restricts the instantiation of a class to one single instance and provides a global point of access to it. It is a design pattern that ensures controlled access to resources or services that must only have a single shared instance throughout an application.

🧠 Key Idea Singleton guarantees a class has only one instance while providing a controlled global access point to that instance.

⚔️ Core Details: - The Singleton pattern involves a private static variable that holds the sole instance of the class. - It uses a private constructor to prevent external instantiation of the class. - A public static method, often named getInstance(), returns the single instance, creating it if necessary. - Singletons are commonly used for managing shared resources like database connections or configuration settings. - Thread safety is a critical concern in Singleton implementation to avoid multiple instances in concurrent environments. - Variations include eager initialization, lazy initialization, and double-checked locking to balance resource use and thread safety.

🎯 Why It Matters: - Singleton ensures resource efficiency by preventing redundant object creation where only one object is needed. - It simplifies access to shared data or services by providing a single, globally accessible instance. - Proper Singleton implementation avoids synchronization issues in multi-threaded applications, ensuring reliability. - Understanding Singleton helps in designing scalable and maintainable software architectures by controlling object lifecycle and access.

🧠 Quick Recall: - Singleton Pattern - ensures a single instance of a class - getInstance() Method - provides global access to the singleton instance - Private Constructor - prevents external class instantiation - Thread Safety - critical for Singleton in multi-threaded contexts - Double-Checked Locking - optimization for thread-safe lazy initialization