Single-Case mode

In general, design patterns fall into three broad categories:

Create five types of models: Factory method mode, abstract Factory mode, singleton mode, builder mode, prototype mode.

Structure mode, a total of seven kinds: Adapter mode, adorner mode, proxy mode, appearance mode, bridging mode, combined mode, enjoy the meta-mode.

There are 11 types of behavioral Patterns: Strategy mode, template method mode, observer mode, iteration sub-mode, responsibility chain mode, Command mode, Memo mode, state mode, visitor mode, mediator mode, interpreter mode.

The singleton pattern ensures that there is only one instance of a class, and that it provides this instance to the system by itself, and the singleton pattern is divided into lazy and a hungry man types:

A hungry man is thread-safe, but relatively time-saving:

1 classsingleton1{2     Private StaticSingleton1 instance =NewSingleton1 ();3     4     PrivateSingleton1 () {}5     6      Public StaticSingleton1 getinstance () {7         returninstance;8     }9}

Lazy if not locking is not thread-safe, but relatively wasteful running time:

1 classsingleton2{2     Private StaticSingleton2 instance =NULL;3     4     PrivateSingleton2 () {}5     6      Public Static Singleton2 getinstance () {//Add synchronized keyword to the method is thread-safe7         if(NULL==instance)8Instance =NewSingleton2 ();9         returninstance;Ten     } One}

In addition, a hungry man also has a way of using an inner class implementation:

1 classsingleton3{2     Static classinner{3         StaticSingleton3 instance =NewSingleton3 ();4     }5     6     PrivateSingleton3 () {}7     8      Public StaticSingleton3 getinstance () {9         returninner.instance;Ten     } One}

In the development, the use of a hungry man-style more.

Single-Case mode