题解 | 统计字符

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);

        while (in.hasNext()) {
            String str = in.nextLine();

            int num1 = 0;
            int num2 = 0;
            int num3 = 0;
            int num4 = 0;

            for (char c : str.toCharArray()) {
                if (Character.isDigit(c)) {
                    num3++;
                } else if (Character.isSpaceChar(c)) {
                    num2++;
                } else if(Character.isLetter(c)) {
                    num1++;
                } else {
                    num4++;
                }
            }

            System.out.println(num1);
            System.out.println(num2);
            System.out.println(num3);
            System.out.println(num4);
        }
    }
}