The differences between Java abstract classes and interfaces

Member Differences

Abstract class:

Member variables: Can be variables, or constants

Construction method: Available

Member methods: can be abstract or non-abstract

Interface:

Member variable: can only be a constant

Member methods: can only be abstracted

Relationship Differences

Classes and classes:

Inheritance, single inheritance

Classes and Interfaces:

Implementation, single implementation, multi-implementation

Interfaces and interfaces:

Inheritance, single inheritance, multiple inheritance

Differences in design concepts

Abstract class: The relationship of being a is embodied by inheritance. What is defined in the abstract class should be the common function of the inheritance system.

Interface: The implementation embodies the relationship of like a. The extension functionality of the inheritance system is defined in the interface.

The differences between Java abstract classes and interfaces