Singleton Pattern

Analogy: pattern

The Singleton Pattern is like a King.

A Kingdom can only have ONE King. If you ask for the King, you get the same person every time. You don't get a new King cloned for every request.

The King

Try to create multiple Kings.

The first time, a King is born (Created).
Every subsequent time, the SAME King is returned.

The King (Singleton Pattern)

Laws of the Land

"There can be only ONE King in the Kingdom instance!"

The Royal Court

Empty Throne

Kingdom Access Log

// Waiting for constructor call...

The Code

Make the constructor private and provide a static method to get the instance.

Java Example

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class King {
    private static King instance;

    // Private Constructor
    private King() {}

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