Java single-instance mode detailed

1, Lazy mode:

Features:lazy loading is obvious, that is, when needed to load, that is, we often say lazy loading.

(1) Thread is unsafe:

public class Singleton {      private static Singleton instance;        public static Singleton getinstance () {      if (instance = = null) {          instance = new Singleton ();      }      return instance;      }  }

(2) Thread safety:

2. Public class Singleton {
4.      private   static Span style= "margin:0px; padding:0px; Border:none; Background-color:inherit "> SINGLETON INSTANCE;  
6.   
7.       public   static   synchronized  singleton getinstance ( )  {  
9.      if   (instance ==  null )  {  
11.         instance =  new  singleton ();   
13.     }  
15.      return  INSTANCE;  
17. }
19. }

Java Singleton mode detailed