Singleton Pattern
There can be only one.
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)
Rule of the Kingdom
"There can be only ONE King!"
Empty Throne
// System Log waiting...
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;
}
}
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Factory Pattern