题解 | #统计字符#

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

// 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) throws IOException {
       BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
       String str = br.readLine();
       char[] chars = str.toCharArray();

        int count1 = 0;
        int count2 = 0;
        int count3 = 0;
        int count4 = 0;

       for(int i = 0;i < chars.length;i++){
            if(((int) chars[i] >= 65 && (int)chars[i] <= 90) || ((int) chars[i] >= 97 && (int)chars[i] <= 122)){
                count1++;
            }else if(chars[i] == ' '){
                count2++;
            }else if((int)chars[i] >=48 && (int)chars[i] <= 57){
                count3++;
            }else{
                count4++;
            }
       }
       System.out.println(count1);
       System.out.println(count2);
       System.out.println(count3);
       System.out.println(count4);
    }
}

利用字符对应的ASCII即可求解