Lesson 10: Java setup and execution model: Project integration

Concept Explanation

This lesson ties the basics together by placing Java code in a small project-style example instead of an isolated snippet. You will work with a simple service, feed it real input, and observe how small design choices affect clarity and maintenance. The main goal is to practice integration: connecting methods, state, and output in a way that still feels organized when the code grows beyond a single task.

Where to Put the Code

1. Define color and position variables at the top.
2. Create shape drawing or placement logic in the middle.
3. Render output (print, canvas, SVG, or styled block) at the end.

Command Reference

• Run the project example once, then trace how data moves from main into the service and back out as output.
• Create a small input set with two SKUs and verify that the service stores each result correctly.
• Refactor one piece of logic into its own method so the class becomes easier to test.
• Document one design decision that helps this example feel like a real mini project instead of a loose code snippet.

Step-by-step Guide

1. Read the flow from main to service and identify where state is stored.
2. Run the baseline version without edits and confirm the starting output.
3. Make one focused change, such as rejecting bad quantities or supporting another item lookup.
4. Test one expected case and one edge case to verify the integration still works.
5. Finish with a quick checklist covering clarity, correctness, and whether each class has a clear job.

Practice Exercises

• Expand the example so it can remove stock as well as add it.
• Create a second mini project using the same structure for tasks, tickets, or library books.
• Write a short output report that proves the service behaves correctly after several operations.

Coding Challenges

• Implement two versions of the inventory logic and compare which one is easier to maintain.
• Design a slightly larger scenario with multiple services and explain how you would keep responsibilities separate.

Mini Practice Tasks

• Add a guard clause for invalid or empty item codes.
• Write one quick manual check for a missing SKU lookup.
• Summarize in one line what this mini project is responsible for.