Error that this class has not inherited a abstract method I created

Error: The type Estimation must implement the inherited abstract method Step.forwardit(int, String, String, String)

How do I find out the list of abstract methods attached. Where do I find this in Eclipse?

You look at the class you're attempting to inherit or the documentation for that class.

In your your class you can "Right click, choose Source and then Override/Implement Methods..."

This will show you a box with the methods you have to implement preselected for you.

You can also having your class open, click the name of the class and then Ctrl+1, this will bring up a little dialog where you can select "Add unimplemented methods"

// Json