Use AddSubscriberToList Method

Use the AddSubscriberToList helper method to add a subscriber to a list (EmailAddress, Lists, SubscriberKey). This method applies to new subscribers in an account or existing subscribers added to an additional list.

Ruby

PHP

Python

CSharp

Java

Documentation for the Fuel Java SDK can be found at http://salesforce-marketingcloud.github.io/FuelSDK-Java/