[Java] abstract classes and abstract methods

Outline

An abstract class may not contain abstract methods,
as long as an abstract method where the class is abstract, you can.

Such a method is not an abstract class is abstract and can not create object directly, there use in some special scenarios.

Sample Code

//父类
public abstract class Fu {
    public Fu() {
        System.out.println("抽象父类构造方法执行！");
    }
    public abstract void eat();
}

//子类
public class Zi extends Fu {

    public Zi() {
        // super();
        System.out.println("子类构造方法执行");
    }
    //子类必须重写抽象父类的抽象方法，除非子类也是抽象类
    @Override
    public void eat() {
        System.out.println("吃饭饭");
    }
}

Precautions