Singleton3.java

public final class Singleton3{
	private static class Handler{
		private static final Singleton3 INSTANCE = new Singleton3();
	}
	
	private Singleton3(){
		if (null != Handler.INSTANCE){
			throw new IllegalArgumentException("Already instantiated.");
		}
	}
	
	public static final Singleton3 getInstance(){
		return Handler.INSTANCE;
	}
}