C语言程序设计教程（第三版）课后习题6.2 （Java代码）

import java.util.Scanner;

public class Main {

        public static void cs(String a){

                char[] array = a.toCharArray();

                int Letter=0;

                int Num = 0;

                int Space = 0;

                int Character = 0;

                for(int i=0;i<array.length;i++){

                        array[i] = a.charAt(i);

                        if(65<=array[i]&&array[i]<=90||97<=array[i]&&array[i]<=122)

                                Letter++;

                        else if(48<=array[i]&&array[i]<=57)

                                Num++;

                        else if(array[i]==32)

                                Space++;

                        else

                                Character++;

                }

                System.out.print(Letter+" "+Num+" "+Space+" "+Character);

        }

        public static void main(String[] arg){

                Scanner sc = new Scanner(System.in);

                String a = sc.nextLine();

                cs(a);

        }

}