Java 字符串反转采用二次递归运行过程不懂

悬赏园豆：50 [已解决问题] 解决于 2015-11-18 17:40

public class StringReverse {
    private static String reverse1(String s) {
        int len = s.length();
        System.out.println(s);
        if (len <= 1) {
            System.out.println(s);
            return s;
            //return "0";
        }
        String leftStr = s.substring(0, len / 2);
        String rightStr = s.substring(len / 2, len);
         reverse1(rightStr);
         System.out.println(s);
         reverse1(leftStr);
         System.out.println(s);
         return s;
        // return reverse1(rightStr)+reverse1(leftStr);
    }
    public static void main(String[] args) {
        System.out.println(reverse1("123"));    
    }

}