JAVA不借助工具类翻转字符，数组

    publicstatic void main(String[] args) {
       String[] strs = {"y", "a", "n", "g","f","e","i"};
       System.out.println(Arrays.toString(strs));
       swap(strs);
       System.out.println(Arrays.toString(strs));

    }

    publicstatic void swap(String strs[]) {
       int len = strs.length;
       int as = len / 2;
       for (int i = 0; i < as; i++) {
           String tmp = strs[i];
           strs[i] = strs[len - 1 - i];
           strs[len - 1 - i] = tmp;
       }
    }