[java] abstract class

In the last article, I talked about interfaces. https://qiita.com/QiitaD/items/835ed6ee4e52cb6b214a This time, I will describe "abstract classes" that are often compared with interfaces.

What is an abstract class?

A class that has one or more abstract methods. Abstract methods must be implemented in subclasses, so you can force developers to override them.


There are the following rules for handling abstract classes.

  1. Cannot be instantiated
  2. Must override abstract method
  3. It is necessary to describe the constructor in the subclass.

Differences from the interface

The following is a table of the differences.

Abstract class interface
Method with implementation Can be implemented Cannot be implemented
Member variables Class member variables constant
Multiple inheritance Impossible Yes


Can be implemented as follows

abstract class Viecle {

Subclasses can be implemented by inheriting abstract classes.

abstract class Car extends Vielce {

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