How to match the beginning of the input using Java RegEx?

You can match the beginning of the input using the meta character “\A”.

Example

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 = "\A[0-9]";
      //Compiling the regular expression
      Pattern pattern = Pattern.compile(regex);
      //Retrieving the matcher object
      Matcher matcher = pattern.matcher(input);
      int count = 0;
      if(matcher.find()) {
         System.out.println("Match found ");
      } else {
         System.out.println("Match not found ");
      }
   }
}

Output 1

Enter a String
12 sample text
Match found

Output 2

Enter a String
sample text
Match not found