Hidden Singleton (Java)

gistfile1.java

Hello Everyone,

Today a small tip from me, an extension of the singleton pattern that I call hidden singleton.

We all know the singleton:

public static class MySingleton {

	private static MySingleton mInstance;

	private final int x = 42;

	private MySingleton() {
	}

	public static MySingleton getInstance() {
    		if( mInstance == null ) {
         		mInstance = new MySingleton();
    		}

    		return mInstance;
	}
    
  	public int getX() {
    		return x;
  	}
}

OK, so if we want to get X, we write:

int myOwnX = MySingleton.getInstance().getX();

Ugly, right? Every time getInstance()? We can do better:

public static class MySingleton {

	private static MySingleton mInstance;

	private final int x = 42;

	private MySingleton() {
	}

	private static MySingleton getInstance() { // Note how getInstance() is private now
    		if( mInstance == null ) {
         		mInstance = new MySingleton();
    		}

    		return mInstance;
	}
    
  	public static int getX() { // Note how getX() is now static, too
		return getInstance().x; // Ta-daaa, here's the magic
  	}
}

Now we can just write:

int myOwnX = MySingleton.getX();

Beautiful! (Well, at least a LITTLE bit nicer looking... ;-)