编程之美 最长连续字符

编程之美的一道题
写一个递归算法。求出字符串最长的连续字符的长度。例如“aaaabbbcc”输出4..”ab”输出1

import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.HashMap;

public class Solution {
    public static void main(String args[])
    {
        fun(str.charAt(0));
        System.out.println(result);

    }
    static int currentIndex=0;
    static int result=0;
    static int startIndex=0;
    static String str="ab";
    static int fun(char c)
    {
        if(currentIndex>=str.length())
        {
            return 0;
        }
        if(c==str.charAt(currentIndex))
        {
            if(result<currentIndex-startIndex+1)
            {
                result=currentIndex-startIndex+1;
            }
            currentIndex++;
            return 1+fun(c);

        }
        else
        {
            startIndex=currentIndex;
            fun(str.charAt(currentIndex));

            return 0;
        }
    }

}