public abstract class Animal {
    String color;
    int age;
    String sex;
    abstract void eatThing();
    abstract void logThing();
    
    public Animal (int age) {
        this.age = age;
    }
    public Animal () {
        this.age = 1;
    }
}

package test;

public class Dog extends Animal {
    String loyal;
    
    public void eatThing () {
        System.out.println("eating");
    }
    
    public void logThing () {
        System.out.println("color : " + color + ", age : " + age + ", sex : " + sex);
    }
    
    public Dog (int age) {
        super(age);
    }
    public Dog () {
        super();
    }
    
    public static void main (String[] args) {
        Dog d = new Dog();
        Animal d2 = new Dog(10);
        d.logThing();
        d2.logThing();
    }
}