欧洲老太太毛茸茸

欢乐喜剧人5，敬请期待。Singleton is a common design pattern. In Java applications, a singleton object can ensure that only one instance of the object exists in a JVM. This model has several advantages:鸿蒙开辟，天地始分三界：天界、地仙界、人间界。这都是真的？老太太简直不敢相信自己的耳朵。我会跟我哥哥和板栗哥哥说，让他们放你们离开。The eldest son of the LinsOne problem with the factory method pattern is that the creation of the class depends on the factory class, that is to say, if you want to expand the program, you must modify the factory class, which violates the closure principle. Therefore, from the design point of view, there are certain problems, how to solve them? We use the abstract factory mode to create multiple factory classes, so that once new functions need to be added, we can directly add new factory classes without modifying the previous code. Because the abstract factory is not very easy to understand, let's look at the diagram first, and then it is easier to understand with the code.