Rewriting and overloading

1. rewrite （Override）

It's in the inheritance system , A subclass that implements a method that is identical in method declaration to the parent class .
To satisfy the inside substitution principle （ The child class replaces the parent class ）, There are three limitations to rewriting ：
A subclass method must have access greater than or equal to a superclass method ;
The return type of a subclass method must be the return type of a parent method or its child .
The exception type thrown by a subclass method must be the exception type thrown by the parent class or its subtype .
Use @Override annotation , You can ask the compiler to check if the above three constraints are met .

2. heavy load （Overload）

Exists in the same class , A method that has the same name as an existing method , But parameter types 、 Number 、 There is at least one difference in order .
It should be noted that , Different return values , Everything else being the same is not an overload .