如何设计具有基类中不可用功能的子类？

// 基类
public abstract class Animal {
    public abstract void eat();
}

// 子类
public class Dog extends Animal {
    public void eat() {
        System.out.println("Dog is eating");
    }
    
    public void bark() {
        System.out.println("Dog is barking");
    }
}

// 接口
public interface Flyable {
    void fly();
}

// 子类实现接口
public class Bird extends Animal implements Flyable {
    public void eat() {
        System.out.println("Bird is eating");
    }
    
    public void fly() {
        System.out.println("Bird is flying");
    }
}