[Java] 进制转换

使用Map提高查找效率

import java.util.*;
public class Main {

  private final static int BASE = 16;
  private static Map<Character, Integer> map = new HashMap<Character, Integer>()
  {{
      put('0', 0);
      put('1', 1);
      put('2', 2);
      put('3', 3);
      put('4', 4);
      put('5', 5);
      put('6', 6);
      put('7', 7);
      put('8', 8);
      put('9', 9);
      put('A', 10);
      put('B', 11);
      put('C', 12);
      put('D', 13);
      put('E', 14);
      put('F', 15);
      put('a', 10);
      put('b', 11);
      put('c', 12);
      put('d', 13);
      put('e', 14);
      put('f', 15);
  }};

  public static int getDecimal(String number) {
      int res = 0;
      for (char ch : number.toCharArray()) {
          res = res * BASE + map.get(ch);
      }
      return res;
  }

  public static void main(String[] args) {
      Scanner in = new Scanner(System.in);
      while (in.hasNext()) {
          String number = in.next();
          int res = getDecimal(number.substring(2));
          System.out.println(res);
      }
  }
}