题解 | #字符串反转#

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String input = scanner.nextLine();
        boolean allLowerCase = true;//布尔值 
        for (char c : input.toCharArray()) {
            if (Character.isUpperCase(c)) {//判断c是否为大写
                allLowerCase = false;
                break;
            }
        }
        if (allLowerCase) {//根据是否为大写以确定是否输出
            StringBuilder reversed = new StringBuilder(input).reverse();
            System.out.println(reversed.toString());
        }
        scanner.close();
    }
}