题解 | #统计字符#

Java 利用正则表达式

import java.util.*;
public class Main {
        public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
            while(sc.hasNextLine()) {
                String str = sc.nextLine();
                String str1 = str.replaceAll("[^a-zA-Z]", "");
                String str2 = str.replaceAll("[^ ]", "");
                String str3 = str.replaceAll("[^0-9]", "");
                String str4 = str.replaceAll("[a-zA-Z0-9 ]", "");
                System.out.println(str1.length());
                System.out.println(str2.length());
                System.out.println(str3.length());
                System.out.println(str4.length());
            }
        }
}