How to match non-digits using Java Regular Expression (RegEx)

You can match non-digit character using the meta character "\\D".

Example 1

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Example {
   public static void main(String args[]) {
      //Reading String from user
      System.out.println("Enter a String");
      Scanner sc = new Scanner(System.in);
      String input = sc.nextLine();
      String regex = "\\D";
      //Compiling the regular expression
      Pattern pattern = Pattern.compile(regex);
      //Retrieving the matcher object
      Matcher matcher = pattern.matcher(input);
      int count = 0;
      while(matcher.find()) {
         count++;
      }
      System.out.println("Number non-digit characters: "+count);
   }
}

Output

Enter a String
sample text 2425 36
Number non-digit characters: 13

Example 2

import java.util.Scanner;
public class RegexExample {
   public static void main( String args[] ) {
      //regular expression to accept 5 letter word
      String regex = "\\D{10}";
      System.out.println("Enter input value: ");
      Scanner sc = new Scanner(System.in);
      String input = sc.nextLine();
      boolean result = input.matches(regex);
      if(result) {
         System.out.println("input matched");
      }
      else {
         System.out.println("wrong input");
      }
   }
}

Output 1

Enter input value:
sample abc
input matched

Output 2

Enter input value:
sample1234
wrong input