Java Program to count digits and white spaces in a given string

Program

import java.util.Scanner;
public class CountDigitsAndWhiteSpacesInString {
    public void countDigitWhiteSpaces(String inputStr)
    {
        int digitCount = 0;
        int spacesCount = 0;
        inputStr = inputStr.toLowerCase();
        for(int i = 0; i < inputStr.length(); i++) {    
            //check for Digits
            if(inputStr.charAt(i) >='0' && inputStr.charAt(i) <='9') {    
               // Increment digit count  
               digitCount++;    
            }    
            //Checks for White Spaces    
            else if(inputStr.charAt(i) == ' ') {      
                //Increment spaces count   
                spacesCount++;    
            }              
        }
        System.out.println("Number of Digits: "+ digitCount); 
        System.out.println("Number of Whitespaces: "+ spacesCount);
    }
    public static void main(String[] args)
    {
        CountDigitsAndWhiteSpacesInString countDigitsAndWhiteSpacesInString = new CountDigitsAndWhiteSpacesInString();
        Scanner reader = new Scanner(System.in);
        System.out.print("Enter the String: ");
        String inputString = reader.nextLine();
        countDigitsAndWhiteSpacesInString.countDigitWhiteSpaces(inputString);
    }
}

This program counts the number of digits and white spaces in a given string by iterating through each character and identifying its type.

1. Input:

   • The program accepts a string from the user using the Scanner class.

2. Initialization:

   • Two counters are initialized: digitCount and spacesCount to track the number of digits and white spaces in the string.

3. String Conversion:

   • The input string is converted to lowercase using toLowerCase() for uniform processing (though not strictly necessary for digit and space counting).

4. Iteration Through Characters:

   • A for loop iterates through each character in the string:
     • Digit Check:
       • Each character is checked if it is between '0' and '9'.
       • If it matches, the digitCount is incremented.
     • White Space Check:
       • The character is checked if it is equal to ' ' (a space character).
       • If it matches, the spacesCount is incremented.

5. Output:

   • The program prints the counts of digits and white spaces.

Key Features:

• Character Classification:
  • Differentiates between digits and spaces.
• Efficiency:
  • Processes the string in a single loop.
• Simple Logic:
  • Uses basic conditional checks for digits and spaces.

Output

$ javac CountDigitsAndWhiteSpacesInString.java
$ java CountDigitsAndWhiteSpacesInString
Enter the String: oodlescoop 123
Number of Digits: 3
Number of Whitespaces: 1