蓝桥基础（java版）十六进制转为十进制

import java.util.Scanner;
public class Main {
 
 public static void main(String[] args) {
  Scanner in = new Scanner(System.in);
     while(in.hasNext()) {
  String s = in.next();
     long temp = 0;
     for(int i = 0;i<s.length();i++) {
      char c = s.charAt(i);
      switch (c) {
      case '0': 
     temp = (long) (temp+((long)0*Math.pow(16, s.length()-1-i)));
        break;
      case '1': 
     temp = (long) (temp+((long)1*Math.pow(16, s.length()-1-i)));
        break;
   case '2': 
     temp = (long) (temp+((long)2*Math.pow(16, s.length()-1-i)));
        break;
   case '3': 
     temp = (long) (temp+((long)3*Math.pow(16, s.length()-1-i)));
        break;
   case '4': 
     temp = (long)(temp+((long)4*Math.pow(16, s.length()-1-i)));
        break;
   case '5': 
     temp = (long) (temp+((long)5*Math.pow(16, s.length()-1-i)));
        break;
   case '6': 
     temp = (long)(temp+((long)6*Math.pow(16, s.length()-1-i)));
        break;
   case '7': 
     temp = (long) (temp+((long)7*Math.pow(16, s.length()-1-i)));
        break;
   case '8': 
     temp = (long) (temp+((long)8*Math.pow(16, s.length()-1-i)));
        break;
   case '9': 
     temp = (long) (temp+((long)9*Math.pow(16, s.length()-1-i)));
        break;
   case 'A': 
     temp = (long) (temp+((long)10*Math.pow(16, s.length()-1-i)));
        break;
   case 'B': 
     temp = (long) (temp+((long)11*Math.pow(16, s.length()-1-i)));
        break;
   case 'C': 
     temp = (long) (temp+((long)12*Math.pow(16, s.length()-1-i)));
        break;
   case 'D': 
     temp = (long) (temp+((long)13*Math.pow(16, s.length()-1-i)));
        break;
   case 'E': 
     temp = (long) (temp+((long)14*Math.pow(16, s.length()-1-i)));
        break;
   case 'F': 
     temp = (long) (temp+((long)15*Math.pow(16, s.length()-1-i)));
           break;
      }
     }
     System.out.println(temp);
}}}

调试了很多次，都是因为自己思考不全面加上粗心造成，为了养成好的思考习惯，总结如下
1.首先因为搞错十六进制转换成为八进制的概念不熟悉，让每一个十六进制的数字变为十进制后直接变为字符串相加（粗心）
2.其次是没有加上十六进制中还包括0的情况（思考不全面）
3.因为charAt是从字符串左边的0位开始，所以对于每一位十六进制的数字，都应该乘以十六进制数长度-1-i的次方，而不是i次方

拿到一个题目之后切记不能直接动手去做，而是应该想好大概框架，列举出实现方法的不同情况之后再下手，以前刚开始的习惯还好些，因为做的多了反而有时候不喜欢想完全再动手，一定要脚踏实地一个一个脚印走，切勿急躁。