I. What is a singleton mode singleton mode ensures that there is only one instance of a class in the system and that the instance is easily accessible to the outside world. Two. The singleton mode points to the following three points: one is that the class of the singleton pattern only provides a private constructor, and the second is that the class definition contains a static private object of the class, and three is A static private object that is used to create or get it itself. Three. Class diagram of the singleton pattern four. Code has three forms of code, according to the specific circumstances of the choice;
"One" lazy mode NOTE: Lazy mode, the first time to be quoted, the initialization of the instance, but the thread is not secure; class singleton{ private Singleton Singleton = null; private Singleton () { & nbsp;} public static Singleton getintance () { if (Singleton = = Nu LL) { Singleton = new Singleton (); } return singleton; } } "II" A Hungry Man Mode & nbsp; Note: Static initialization, initialized when the class is loaded; class singleton{ private static final Singleton Singleton = new Singleton (); private Singleton () {} public static Singleton getinstance () { & nbsp Return singleton; } "three" Double locking mode NOTE: thread-safe; class singleton{ prviate Singleton Singleton = null; private Singleton () {} public static S Ingleton getinstance () { if (singleton = = null) { synchronized (Singleton.class) { if (Singl Eton = = null) { singleton = new Si Ngleton (); } } } return singleton; }}
Design mode two: Singleton mode
