题解 | 字符串反转

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNext()) { // 注意 while 处理多个 case
            String a = in.nextLine();
            if (null == a || a.isEmpty()) {
                System.out.print("");
            }
            StringBuilder sb = new StringBuilder();

            for (int i = a.length() - 1; i >= 0; i--) {
                sb.append(a.charAt(i));
            }

            System.out.println(sb.toString());
        }
    }
}