import java.util.Scanner;
import java.util.Stack;

class Animal {
    private String name;
    private String bark;
    private int age;
    private int weight;

    public Animal(String idname, String idbark, int idage, int idweight) {
        // 不是说没有指针吗，这个this又是啥. 你的实例化方法第一个参数还不也是Demo* this，你写语言给我写好的啊.
        this.name = idname;
        this.bark = idbark;
        this.age = idage;
        this.weight = idweight;
    }

    public void showStatus() {
        System.out.printf("\nname: %s,\nbark: %s,\nage: %d,\nweight: %d.", name, bark, age, weight);
    }

    public void sleep() {
        System.out.printf("\n%s is sleeping.", name);
    }

}

// 类的继承
class Penguin extends Animal {
    public Penguin(String myName, String myBark, int myAge, int myWeight) {
        super(myName, myBark, myAge, myWeight);
    }
}

public class App {
    // 递归函数.
    public static int factorial(int x) {
        if (x == 0 || x == 1) {
            return 1;
        }

        else if (x < 0) {
            return -1;
        }

        else {
            return x * factorial(x - 1);
        }
    }
    // 进制转换,试试Java的栈;
    public static String Jinzhi(int num, int std) {
        char[] T = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
                'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
                'U', 'V', 'W', 'X', 'Y', 'Z' };
        boolean flag = true;
        if (num < 0) {
            num = -num;
            flag = false;
        }

        if (num == 0) {
            return "0";
        }
        // Java 封装的栈:
        Stack<Character> st = new Stack<>();

        while (num != 0) {
            st.push(T[num % std]);
            num /= std;
        }

        String result = "";
        if (!flag) {
            result += "-";
        }
        while (!st.empty()) {
            result += st.pop();
        }

        return result;
    }

    public static void main(String[] args) throws Exception {

        // 输入输出:
        System.out.print("\nType an int: ");
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        sc.close();
        System.out.printf("\n%d 的阶乘为: %d", a, factorial(a));

        // 父类.
        Animal cat = new Animal("cat_1", "meow", 3, 15);
        cat.showStatus();

        // 子类.
        Penguin pgin = new Penguin("penguin_1", "gagaga", 3, 15);
        pgin.showStatus();

        int[] arr = new int[10];
        int temp;
        for (int i = 0; i < 10; i++) {
            System.out.printf("\n%d! = %d", i, temp = factorial(i));
            arr[i] = temp;
        }

        System.out.printf("\n255 的 16 进制: %s", Jinzhi(255, 16));

    }

}