Just started learning Java pls help

SPECIEICATION:A friend of yours is setting up a computer building business, and to help customers decide on what components they want in their systeml. The system should keep a catalogue of available parts, which can be displayed to the user, updated and filtered by type or price (or both). The system should also allow the user to build a computer (more accurately a parts list) from parts in the catalogue, add and remove parts from the build, clear the build, see the build (including the total cost). The interface for the prototype will be a simple text interface, where parts are identifed by their position in the catalogue/build. As an advanced feature, your friend would like the user to be able to add several parts in one go Your friend has provided you with a nicely typed out text demonstration of how the system should work, along with some tests can't change the classes or the fields can only import java.util.*; public class ComputerBuilder private Catalogue catalogue private Build currentBuild; public class Build private List parts; public class Catalogue f private List parts; public class Part private String name; private String type; private double price