Heroku Java web app call jar

Question

I'm creating web app to host on heroku. This web app is used to retrieve the credentials of users then I want to feed that input into a regular java app. Is it okay to store the jar of the java app, within my web app then use the Runtime.getRuntime().exec() command on heroku to run execute the jar with the credentials as arguments?

        Process process = Runtime.getRuntime().exec("heroku run \"java - jar java.jar " + 
    "test test test test\"");