Singleton Class in Java : Purpose & Implementation

A Singleton class in Java is a class that allows only one instance to be created throughout the lifetime of the application. It’s used when you want to control the number of instances, particularly when:

✅ Why We Need a Singleton Class in Java :

1. Controlled access to a single resource

• For things like configuration settings, database connections, loggers, or thread pools — you want to share only one instance across the application.

1. Saves memory

• Creating a single instance avoids unnecessary memory usage.

2. Consistency

• You ensure that all parts of the application use the same instance and hence the same state.

How to Create a Singleton Class in Java :

There are multiple ways, but the most common are:

1. Eager Initialization (Thread-safe) :

public class Singleton {
    // Instance created at load time
    private static final Singleton instance = new Singleton();

    // Private constructor
    private Singleton() {}
    // Public method to provide access to the instance
    public static Singleton getInstance() {
        return…