JAVA不借助工具类翻转字符，数组

    public static 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));

    }

    public static 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;         }     }