HJ5 进制转换

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str = in.nextLine();
        String[] s = str.split("");
        int len = s.length;
        int total = 0;
        for(int i = 0; i < len - 2; i++){
            int num = 0;
            switch (s[len - i - 1]){
                case "A":
                    num = 10;
                    break;
                case "B":
                    num = 11;
                    break;
                case "C":
                    num = 12;
                    break;
                case "D":
                    num = 13;
                    break;
                case "E":
                    num = 14;
                    break;
                case "F":
                    num = 15;
                    break;
            }
            if(num == 0){
                num = Integer.parseInt(s[len - i - 1]);
            }
            for(int j = 0; j < i; j++){
                num = num * 16;
            }
            total += num;
        }
        System.out.println(total);
    }
}

1.将字符串转换成单独的字符数组；

2.根据16进制特性从后往前开始计算；

3.进行A~F的匹配；

4.循环计算