字符串累加

public class Test {

    public static void main(String[] args) {
        String token = "aaaaaaaaaaaaaaa";

        long startTime = System.currentTimeMillis();
        for (int i = 0; i < 100; i++) {
            token = strPlus(token);
        }
        System.out.println(token);
        System.out.println((System.currentTimeMillis()-startTime));
    }


    public static String strPlus(String token){
        char[] chars = token.toCharArray();
        char start = 'a';
        char end = 'z';
        int length = chars.length;
        for (int j = length-1; j >=0; j--) {
            char f = chars[j];
            char plus = ++f;
            if(f>end){
                chars[j] = start;
            }else{
                chars[j] = plus;
                break;
            }
        }
        return new String(chars);
    }


}