Effective Java Tips

The previous lesson covered the surface rules: naming, formatting, file layout, the kind of guidance a linter can enforce. This lesson is about the deeper habits that separate Java code that works from Java code that's pleasant to live with for years. Most of these tips come from Joshua Bloch's _Effective Java_, distilled and pointed at the e-commerce code from earlier in the course. Each tip below names a habit, shows the version of the code that ignores it, then the version that follows it, and ends with the trade-off that signals when the habit bends.