public class StringReverse {
    // 字符串反转 数组双指针解法
    // String无法直接操作内部的char数组，避免不了2倍内存开销
    public static void main(String[] args) {
        String str = "1234567";
        char[] chars = str.toCharArray();
        int len = chars.length;
        char x, y;
        for (int index = 0, mid = len >> 1, end = len - 1; index < mid; index++, end--) {
            x = chars[index];
            y = chars[end];
            chars[index] = y;
            chars[end] = x;
        }
        System.out.println(new String(chars));
    }
}