Java: Single-instance design pattern

Design mode:

* Design pattern: The most effective way to solve a certain kind of problem;
* Java has 23 design mode
* Singleton design mode: Solve a class in memory only one object exists;
*
* Want to make sure the object is unique
* 1. To avoid excessive creation of such objects by other programs. Control prevents other programs from setting up this type of object first
* 2. In order for other programs to have access to the class object, you have to customize an object in this class
* 3. In order to facilitate the access of other programs to the custom object, you can provide some external access methods
*
* How do these three parts show up in code?
* 1. Privatize a constructor
* 2. To create an object of this class in a class
* 3. Provides a way to get to the object

* How to describe things and how to describe them.
* When you need to guarantee the object of this thing to be unique in memory, add the above 3 parts.

Simple interest design mode: Recommended use of a hungry man type

1. A Hungry man type

1 //initialize the object first, called: a Hungry man type2 //Sinle class creates an object in memory3     4 class Single5 {6     PrivateSingle () {}7     Private StaticSingle S =NewSingle ();8 9      Public StaticSingle getinstance ()Ten     { One         returns; A     } - } - classDanlidemo the { -      Public Static voidMain (string[] args) -     { -Single SS =single.getinstance (); +     } -}

2. Lazy Type

1 //An object is a method that is called when it is initialized, also called an object's lazy loading, known as: Idle-type2 //The Single2 class enters memory, the object does not exist, and the object is created only when getinstance is called. 3 classSingle24 {5     Private StaticSingle2 s =NULL;6     PrivateSingle2 () {}7     Private StaticSingle2 getinstance ()8     {9         if(s = =NULL)Ten         { Ones =NewSingle2 (); A             returns; -         } -     } the } -  - classDanlidemo - { +      Public Static voidMain (string[] args) -     { +Single2 SS =single2.getinstance (); A     } at}

Java: Single-instance design pattern