L1-017 到底有多二 (15 分) java解题

import java.util.Scanner;

public class Main {
    public static void main(String args[]){
             double sum=0;
             double bei=1;
             int len;
             int count=0;
        String str=null;
        Scanner in=new Scanner(System.in);
        str=in.next();
        len=str.length();
        if (str.charAt(0)=='-'){
            len=str.length()-1;
            bei=1.5;
        }
        for (int i=0;i<str.length();i++){
            if (str.charAt(i)=='2'){
                count++;
            }
        }
        int bei2=1;
        if (Integer.parseInt(str.charAt(str.length()-1)+"")%2==0){
            bei2=2;
        }
        sum=((double) count/len)*bei*bei2*100;
        System.out.printf("%.2f%s",sum,"%");
    }
}