A single-instance design pattern and multiple design patterns for Java design patterns

Singleton design Pattern: The construction method is privatized, the static property and method are defined inside the class, and the static method is used to get the instantiated object of this class; no matter how many instanced objects are generated externally, there is essentially only one instanced object

A hungry man single-case design

classsingleton{Private Static FinalSingleton INSTANCE =NewSingleton ();//produces an instantiated object    PrivateSingleton () {}//Encapsulation Construction Method     Public StaticSingleton getinstance () {returnINSTANCE;//get instantiated Object    }     Public voidprint () {System.out.print ("Hello word"); }} Public classtest{ Public Static voidMain (String args[]) {Singleton s= Singleton.getinstance ();//regardless of how many times the getinstance () method is called, the resulting instantiation object is the sameS.print (); }}

Lazy Style design mode

classsingleton{Private Static FinalSingleton INSTANCE;//defines an object of this class that is not instantiated    PrivateSingleton () {}//Encapsulation Construction Method     Public StaticSingleton getinstance () {if(INSTANCE = =NULL) {INSTANCE=NewSingleton (); }        returnINSTANCE;//get instantiated Object    }     Public voidprint () {System.out.print ("Hello word"); }} Public classtest{ Public Static voidMain (String args[]) {Singleton s= Singleton.getinstance ();//regardless of how many times the getinstance () method is called, the resulting instantiation object is the sameS.print (); }}

Multiple design Patterns: privatization of construction methods, resulting in a specific number of objects

classsex{PrivateString sex; Private Static FinalSex man =NewSex ("Male"); Private Static FinalSex WOMAN =NewSex ("female"); Privatesex (String sex) { This. Sex =sex; }     Public StaticSex getinstance (intch) {        Switch(CH) { Case1:                returnMan ;  Case2:                returnWOMAN; default:                return NULL; }    }     PublicString toString () {returnsex; }} Public classtest{ Public Static voidMain (String args[]) {Sex s= Sex.getinstance (1);    System.out.println (s); }}

A single-instance design pattern and multiple design patterns for Java design patterns