16进制转10进制

char 与char 比较用==

字串与字串比较用equals

import java.util.Scanner;
import java.util.prefs.BackingStoreException;

public class Main {
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		char[] s = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
		String in = sc.nextLine();
		char[] inChar = in.toCharArray();
		
		long sum = 0 ;
		for(int i = 0 ; i < inChar.length; i++ ){
			for(int j = 0 ; j < s.length; j++){
				if(s[j]== inChar[i]){
					sum += j*Math.pow(16,inChar.length - 1-i);//输入的顺序颠倒过来
					break;
				}
			}
		}
		System.out.println(sum);
		
	}
}