抽象参数和方法入门

抽象类是指不能被实例化的类，其中可能包含抽象方法和抽象参数。抽象方法没有实现，需要在子类中被实现，而抽象参数则需要在子类中被具体化。

示例代码：

public abstract class Animal {
    protected String name;
    protected int age;

    public Animal(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public abstract void eat();

    public abstract String sound();

    public void sleep() {
        System.out.println(name + " is sleeping.");
    }
}

public class Dog extends Animal {
    private String breed;

    public Dog(String name, int age, String breed) {
        super(name, age);
        this.breed = breed;
    }

    @Override
    public void eat() {
        System.out.println(name + " is eating dog food.");
    }

    @Override
    public String sound() {
        return "Woof!";
    }
}

public class Cat extends Animal {
    private String color;

    public Cat(String name, int age, String color) {
        super(name, age);
        this.color = color;
    }

    @Override
    public void eat() {
        System.out.println(name + " is eating cat food.");
    }

    @Override
    public String sound() {
        return "Meow!";
    }
}

public class Main {
    public static void main(String[] args) {
        Dog myDog = new Dog("Buddy", 3, "Golden Retriever");
        Cat myCat = new Cat("Fluffy", 2, "White");

        myDog.eat(); // Output: Buddy is eating dog food.
        myCat.eat(); // Output: Fluffy is eating cat food.

        myDog.sleep(); // Output: Buddy is sleeping.
        myCat.sleep(); // Output: Fluffy is sleeping.

        System.out.println(myDog.sound()); // Output: Woof!
        System.out.println(myCat.sound()); // Output: Meow!
    }
}