Singleton Pattern.md

Definition

The Singleton Pattern ensures that a class has only one instance throughout the application's life-cycle and provides a global point of access to that instance. Remember:

• A singleton object is not a "glorified" global variable!
• Prefer dependency injection over direct singleton usage if possible.

When to Use?

• You need exactly one instance of an object across your system.
• Having multiple instances will cause redundancy, corruption, or conflict.

Use-case Examples (Real-world Applications)

• Logger
• Database Connection Pool

Example

Java

public class Singleton {
    private static Singleton instance;

    private Singleton() {}

    public static synchronized Singleton getInstance() {
        if (instance == null) {
            instance = new Singleton();
        }
        return instance;
    }
}