Java程序：编写程序接收用户输入字符串，统计字符串中大写字母、小写字母和数字的个数，将字符串反转输出（不用reverse()方法），判断是否为回文字符串

import java.util.Scanner;

public class StringProcessing {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入一个字符串: ");
        String str = scanner.nextLine();

        int counts[] = count(str);
        System.out.println("大写字母: " + counts[0] + ", 小写字母: " + counts[1] +", 数字: " + counts[2]);
        System.out.println("反转结果: " + reverse(str));
        if(palindromic(str)) {
            System.out.println("是回文字符串");
        } else {
            System.out.println("不是回文字符串");
        }
        scanner.close();
    }
    public static int[] count(String str) {
        int upperCount = 0; 
        int lowerCount = 0;
        int digitsCount = 0;
        
        for (char ch : str.toCharArray()) {
            if (Character.isUpperCase(ch)) {
                upperCount++;
            } else if (Character.isLowerCase(ch)) {
                lowerCount++;
            } else if (Character.isDigit(ch)) {
                digitsCount++;
            }
        }

        return new int[]{upperCount, lowerCount, digitsCount};
    }
    public static String reverse(String str) {
        String reverseStr = "";
        for ( int i = str.length() - 1; i >= 0; i--) {
            reverseStr += str.charAt(i);
        }
        return reverseStr;
    }
    
    public static boolean palindromic(String str) {
        for ( int i = 0; i < str.length() / 2; i++) {
            if (str.charAt(i) != str.charAt(str.length() - 1 - i)) {
                return false;
            }
        }
        return true;
    }
}