The difference between the implementation of the A Hungry man mode and the static inner class implementation of the Singleton pattern

The A Hungry Man method implementation code is as follows:

 PackagePriv.jack.dp.demo.singleton;/** * @authorJack * A hungry man mode singleton * Thread safety * does not support lazy loading, easy to generate garbage objects * Advantages: No lock, execution efficiency will improve. */ Public classHungrysingleton {Private StaticHungrysingleton INSTANCE =NewHungrysingleton (); PrivateHungrysingleton () {System.out.println ("Init ..."); }         Public voidHello () {System.out.println ("Hello world!"); }         Public StaticHungrysingleton getinstance () {returnINSTANCE; }         Public Static voidmain (String [] args) {System.out.println ("Main start ...");     Hungrysingleton.getinstance (). hello (); }}

Static inner class implementation code:

 PackagePriv.jack.dp.demo.singleton;/** * @authorJack * Supports lazy loading, multi-threaded * objects are created at the time of use*/ Public classStaticinnersingleton {Private Static classstaticinnersingletonholder{Private Static FinalStaticinnersingleton INSTANCE =NewStaticinnersingleton (); }        PrivateStaticinnersingleton () {System.out.println ("Init ..."); }         Public Static FinalStaticinnersingleton Getinstantce () {returnstaticinnersingletonholder.instance; }         Public voidHello () {System.out.println ("Hello world!"); }             Public Static voidmain (String [] args) {System.out.println ("Main start ...");     Staticinnersingleton.getinstantce (). hello (); }    }

A hungry man mode run result

init...main Start...hello  World!

Static internal class mode run result

main Start...init...hello  world!

The difference is that static internal classes are lazy-loaded and take into account high-performance benefits.

The difference between the implementation of the A Hungry man mode and the static inner class implementation of the Singleton pattern