JAVA的多態（強制轉換）

abstract class Animal {
    String name;
    String color;

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

    public abstract void run();
}

class Dog extends Animal {

    public Dog(String name, String color) {
        super(name, color);
    }

    public void run() {
        System.out.println(color + name + "四條腿跑");
    }

    public void find() {
        System.out.println(color + name + "找骨頭");
    }
}

class fish extends Animal {

    public fish(String name, String color) {
        super(name, color);
    }

    public void run() {
        System.out.println(color + name + "游的快");
    }

    public void eat() {
        System.out.println(color + name + "吃面包屑");
    }
}

public class Demo {
    public static void main(String[] args) {
        // Animal a = new fish("小魚", "黃色");
        // 強制類型轉換就能調用到子類的方法
        // fish f = (fish) a;
        // f.eat();

        fish f = new fish("小魚", "黃色");
        printThe(f);
        Dog d = new Dog("小狗", "花的");
        printThe(d);
    }

    // 定義一個函數接收任意類型的動物對象，在函數內部調用動物特有的方法
    public static void printThe(Animal a) {
        if (a instanceof fish) {
            fish f = (fish) a;
            f.eat();
        } else if (a instanceof Dog) {
            Dog d = (Dog) a;
            d.find();
        }
    }
}