Simple interest mode - evil Chinese style

/* *  Singleton design pattern （ a key ） * *  Single case ： Unique instance , Throughout Java In the system , There is only one object of a class . * *  form ： * 1、 hungry （ evil ） Chinese style  *  Whether the user wants to use this object or not , Create this object first . * 2、 Slacker type  *  Only when the user gets this object , To create this object . * *  No matter what kind of singleton design pattern is written ： * （1） The constructor of this class is Privatization  --> Make sure our users don't create the second object at will ... * （2） This unique instance must be created in this class , And use a static variable to store . * * */
public class TestSingleton {
    

}

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/* *  One 、 Hungry Chinese style  * 1、 Use one ( Public static constants ) To save this unique instance object  * 2、 Enumeration class  * 3、 Use one ( Private static constants ) To save this unique instance object , Use a static method to return this unique object  */
public class TestHungry {
    
	public static void main(String[] args) {
    
// Hungry h = new Hungry();// Cannot create object outside 
		
		// How to get the object of this singleton 
		Hungry h = Hungry.INSTANCE;
		
		HungryEnum he = HungryEnum.INSTANCE;
		
		HungryDemo hd = HungryDemo.getInstance();
	}
}
class Hungry{
    
	//（2） Use a static variable , To store this unique object 
	// This object is created when the class is initialized 
	public static final Hungry INSTANCE = new Hungry();
	


enum HungryEnum{
    
	INSTANCE
}

class HungryDemo{
    
	//（2） Use a static variable , To store this unique object 
	// This object is created when the class is initialized 
	private static final HungryDemo INSTANCE = new HungryDemo();
	
	
	//(1) Constructor privatization 
	private HungryDemo(){
    
		
	}
	
	public static HungryDemo getInstance(){
    
		return INSTANCE;
	}
}