The difference between abstract classes and interfaces

First, let's look at abstract classes , What is an abstract class ？

1、 Abstract classes don't necessarily have abstract methods , Abstract classes must have keywords abstract To modify

2、 If a class contains abstract methods , So this class must be an abstract class

3、 Abstract classes cannot be used final Embellishment stands for , Because abstract classes are used for inheritance , however final Modified representative cannot be modified , Non inheritable

The difference between interface and abstract class ？

1、 A subclass can only inherit one abstract class , But you can implement multiple interfaces

2、 Abstract classes have construction methods , Interface has no constructor

3、 Abstract classes can have common member variables , There cannot be

4、 Abstract classes and interfaces can have static member variables , But member variables in abstract classes can be of any type , The interface can only be public static final（ Default ）

5、 There doesn't have to be an abstract method in an abstract class , But the methods in the interface must be abstract

6、 Abstract classes can have static methods , There cannot be static methods in an interface

7、 The methods in an abstract class can be public、protected, Methods in an interface can only be public