Unkown Java error in eclipse

Been working on an assignment in college. The objective is to build a robot by displaying three images (head, body, legs) based on a selection from the user using a JButton. The project must implement the java builder pattern. One of my friends was helping me with it and was demonstrating his project on my laptop. It compiled succsefuly on his and others machines but for some strange reason gave me an error here.

legoRobotB.addActionListener(i --> letsMakeRobotTogether(new RobotDirector(legoRobotBuilder)));
stickmanRobotB.addActionListener(i --> letsMakeRobotTogether(new RobotDirector(stickmanRobotBuilder)));

The error occurs under neath the "i" on both lines. I am using eclipse keplar on windows and my library is jre 1.8.0

I would appreciate any help Thanks in advance