Java design pattern: Singleton design pattern

Single example design mode: Solve a class in memory only one object, the design pattern of a single case there are two main ways: lazy, a hungry man-style.

1. To ensure that there is only one object, prevent other programs from creating the class object first.

2. In order to ensure that other programs have access to such objects, it is necessary to create an object of that class first in this class.

3. Provide a way for other programs to access the object.

One: Lazy type single case

Java design pattern: Singleton design pattern