关于继承方面的构造函数等知识汇总

Constructors Are Not Inherited

构造函数是不会继承的，若是子类调用父类构造函数，需要先加上super()函数（不加会默认用无变量的super())

Abstract classes

Interface

• All methods must be public.
• All variables must be public static final.
• Cannot be instantiated
• All methods are by default abstract unless specified to be default
• Can implement more than one interface per class

Abstract

• Methods can be public or private
• Can have any types of variables
• Cannot be instantiated
• Methods are by default concrete unless specified to be abstract
• Can only implement one per class

抽象基本囊括interface的功能，甚至更多