JAVA菜单驱动程序，用于检查字符是字符串、数字还是特殊字符

Suppose the entered character is ‘a’ then the output should be “Entered character is a String”.

Suppose the entered character is ‘1’ then the output should be “Entered character is a number”.

Suppose the entered character is ‘$’ then the output should be “Entered character is a Special character”.

Character.isLetter(ob1)

Character.isDigit(ob1)

(!Character.isDigit(ob1)&& !Character.isLetter(ob1)&& !Character.isWhitespace(ob1))

import java.util.*;
public class Main {
   public static void main(String args[]) {
      Scanner sc = new Scanner( System.in );
      System.out.println("Enter a character to check if it's a Number, String or a Special character");
      char ob1 = sc.next().charAt(0);

      System.out.println("Now choose the operation you want to perform from the menu given below. ");

      mainLoop: while (true) {
         Scanner inn = new Scanner( System.in );
         System.out.println("\n***Menu***");
         System.out.println("1. Check if a character is number");
         System.out.println("2. Check if a character is String");
         System.out.println("3. Check if a character is Special character");
         System.out.println("4. Terminate the program");
         System.out.println("Enter action number (1-4): ");
         int command;
         if ( inn.hasNextInt() ) {
            command = inn.nextInt();
            inn.nextLine();
         }
         else {
            System.out.println("\nILLEGAL RESPONSE. YOU MUST ENTER A NUMBER.");
            inn.nextLine();
            continue;
         }
         switch(command) {
            case 1:
            if (Character.isDigit(ob1)) {
               System.out.println("Character is a number!");
            } else {
               System.out.println("Character is not a number!");
            }
            break;
            case 2:
            if (Character.isLetter(ob1)) {
               System.out.println("Character is a String!");
            } else {
               System.out.println("Character is not a String!");
            }
            break;
            case 3:
            if (!Character.isDigit(ob1)
            && !Character.isLetter(ob1)
            && !Character.isWhitespace(ob1)) {
               System.out.println("Character is a Special Character!");
            } else {
               System.out.println("Character is not a Special Character!");
            }
            break;
            case 4:
            System.out.println("Program terminated");
            break mainLoop;
            default:
            System.out.println("Wrong choice!!");
         }

      }

   }
}

Enter a character to check if it's a Number, String or a Special character
t
Now choose the operation you want to perform from the menu given below.
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
1
Character is not a number!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
3
Character is not a Special Character!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
2
Character is a String!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
$
ILLEGAL RESPONSE. YOU MUST ENTER A NUMBER.
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
1
Character is not a number!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
3
Character is not a Special Character!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
2
Character is a String!
***Menu***
1. Check if a character is number
2. Check if a character is String
3. Check if a character is Special character
4. Terminate the program
Enter action number (1-4):
4
Program terminated