Library
Current regex:
Numbers only regex (digits only) Java
Java

Java

ZIP code regex Java
ZIP code
XML regex Java
XML
UUID regex Java
UUID
URL regex Java
URL
Street address regex Java
Street address
SSN regex Java
SSN
Regex match words Java
Words match
Phone number regex Java
Phone number
Password regex Java
Password
Numbers only regex (digits only) Java
Numbers only (digits only)
Mac address regex Java
Mac address
IP address regex Java
IP address
HTML regex Java
HTML
GUID regex Java
GUID
Email regex Java
Email
Date regex Java
Date
Numbers only regex (digits only) Java

Numbers only (digits only)

Numbers only (or digits only) regular expressions can be used to validate if a string contains only numbers.

JavaScript
JavaScript
Python
Python
Java
Java
C#
C#
PHP
PHP

Basic numbers only regex

Below is a simple regular expression that allows validating if a given string contains only numbers:

Pattern.compile("^\\d+$")

Test it!
/^\d+$/

True

False

Enter a text in the input above to see the result

Example code in Java:

import java.util.regex.Pattern;
import java.util.regex.MatchResult;
import java.util.Arrays;

public class Main {

    public static void main(String []args) {
        // Validate number
        boolean isMatch = Pattern.compile("^\\d+$")
               .matcher("42")
               .find(); 
        System.out.println(isMatch); // prints true
        
        // Extract number from a string
        String[] matches = Pattern.compile("\\d+")
                          .matcher("Your message was viewed 203 times.")
                          .results()
                          .map(MatchResult::group)
                          .toArray(String[]::new);
        System.out.println(Arrays.toString(matches)); // prints [203]
    }
}

Real number regex

Real number regex can be used to validate or exact real numbers from a string.

Pattern.compile("^(?:-(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))|(?:0|(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))))(?:.\\d+|)$")

Test it!
/^(?:-(?:[1-9](?:\d{0,2}(?:,\d{3})+|\d*))|(?:0|(?:[1-9](?:\d{0,2}(?:,\d{3})+|\d*))))(?:.\d+|)$/

True

False

Enter a text in the input above to see the result

Example code in Java:

import java.util.regex.Pattern;
import java.util.regex.MatchResult;
import java.util.Arrays;

public class Main {

    public static void main(String []args) {
        // Validate real number
        boolean isMatch = Pattern.compile("^(?:-(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))|(?:0|(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))))(?:.\\d+|)$")
               .matcher("121220.22")
               .find(); 
        System.out.println(isMatch); // prints true
        
        // Extract real number from a string
        String[] matches = Pattern.compile("(?:-(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))|(?:0|(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))))(?:.\\d+|)")
                          .matcher("Pi equals to 3.14")
                          .results()
                          .map(MatchResult::group)
                          .toArray(String[]::new);
        System.out.println(Arrays.toString(matches)); // prints [3.14]
    }
}

Test it!

True

False

Enter a text in the input above to see the result

Notes on number only regex validation

In Java you can also validate number by trying to parse it:

try {
    double d = Double.parseDouble("1.12");
} catch (NumberFormatException nfe) {
    return false;
}