How do I implement the Luhn algorithm?

Question

I am trying to create a program to validate 10 to 12 digit long number sequences based on the luhn algorithm, but my program keeps on telling me that every number is invalid

Answer 1

use org.apache.commons.validator.routines.checkdigit.LuhnCheckDigit.LUHN_CHECK_DIGIT.isValid(number)

Maven Dependency:

    commons-validator
    commons-validator
    1.5.1