but I can't figure out how to initialize these things
Are you confused about initializing the double variables? Since a double is a primitive, it is given a default value when you create it. For doubles, this value is 0.0
. So, the current statements you have no will, by default, initialize each of those doubles to 0.
For a list of primitives and their defaults, see this link: Primitive Data Types (The Java™ Tutorials > Learning the Java Language > Language Basics)
Now if your question is about how to set those variables based on the user's specifications (or hard-coded specifications), create a constructor where you should set the values of those variables. I'm sure you have basic notes on how to create a constructor.