写代码的时候总是各种问题，不过最后还是通过了，花了不少时间调整。

你看看我的吧

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        String str = s.nextLine()+"#";
        s.close();
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < str.length();i++) {
            for (int j = i + 1; j < str.length(); j++) {
                if (str.charAt(i) != str.charAt(j)){
                    if (j - i > 1) {sb.append(j - i - 1);}
                    sb.append(str.charAt(i));                                        
                    i=j-1;
                    break;
                }
            }
        }
        System.out.println(sb);
    }
}