The parameter type in Java / return value type

Parameter Type / Return Value Type:

##数据类型：
    ###基本类型：
    ###引用类型：
        ####数组
        ####类
        ####接口
        

Parameter Type / return value type is the case of classes and interfaces:

1. The parameter type is a case of an ordinary class

Why write static, because the main is static, if the show is non-static, then the main is not called. Is static ancestors, advanced memory. Non-static descendants

2, where the parameter type is an abstract class

When you see the parameters of an abstract class, need to pass a subclass object of this class, she is an abstract class that can not create object.

3, where the interface is the parameter type

When you see the method parameter is the time to have an interface, you need to pass a subclass object interface, she is the interface can not create object