判断一个字符串内字符重复的字符个数

public class Chongfu {int [] it;void panduan(String s){int [] it = new int[26];char [] cr =s.toCharArray();int count=0;for(int i=0;i<cr.length;i++){int num = (int)cr[i]-97;if(it[num]==0){it[num]=1;count++;}}System.out.println(count);     }public static void main(String [] args){Chongfu cf = new Chongfu();cf.panduan("ddddddddddddddddddddd");}}