Differences between overloads, rewrites, abstract classes and interfaces

    heavy load ：

    A way for classes to handle different types of data in a unified way . Multiple functions with the same name exist at the same time , Determine which method to use according to the number and type of incoming data .

    Is a manifestation of polymorphism , Its polymorphism is reflected in judging which method to use according to the number and type of incoming data .

    , sex ： Same method name , The type or number of parameter lists are different , Independent of return value . Two methods with different return values , In the same class is not considered overloaded , Instead, compilation errors will occur .

    rewrite ：

     Polymorphism between parents and children , Redefining the function of the parent class . That is, a method defined in a subclass has the same name and parameters as its parent class . 

     If a method in a subclass has the same method name as a method in a parent class 、 Return type and parameter list , Then the new method will cover the original method . If you need the original method in the parent class , You can use super keyword , The keyword refers to the parent class of the current class .

    The difference between abstract classes and interfaces ：

    1. Abstract classes are still a kind of class , There's a way to structure , Only inheritance . It's an abstraction of things , Contains properties and behaviors , That is, you can have non abstract methods and member variables .

    2. There can only be abstract methods in an interface , Can't instantiate , Can be implemented .