Write a java program that contains $2$ classes as follow:

$1-$ Niven class: it contains a method called $$IsNiven$$ which returns true if the passed integer is Niven number, or false if the passed integer is not a Niven number.

$2-$ NivenFile class: it reads numbers from a file named $$numbers$.$dat$.$ and check whether the number is Niven or not by calling $$IsNiven$$ method, if the number is Niven store it in a file named $$niven$.$dat$,$ else store it in a file named $$nonniven$.$dat$.$

Note: A Niven number is any whole number that is divisible by the sum of its digits. For example, $126$ is a Niven number because the sum of its digits $1+2+6,$ is $9.$