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Turn a UML box into a Java class stub for your team

Practice: Setting limits and rules. About 5 minutes.

About this exercise

Your team splits work by class, so you're writing the LibraryCard skeleton from the UML for teammates to fill in. Team rules: the class is public final, fields are private final with the UML names, the constructor stores loans as a defensive copy with List.copyOf(loans), there's a getter for each field and no setters, and checkout and returnBook stubbed with throw new UnsupportedOperationException("TODO"). Your course bans records and Lombok. Exactly 1 code block of at most 34 lines, under 20 words of text.

Common mistakes when you ask AI for this

  • Getting it implemented. The AI writes the 5-loan check, which is Priya's task next week. Try: Say: "Stub checkout and returnBook with throw new UnsupportedOperationException(\"TODO\")."
  • A record or Lombok. On Java 17 the AI may use a record or @Getter, which your course bans. Try: Add: "Plain class, no records, no Lombok."
  • Missing the team rules. The AI won't make the class final or copy the list unless told, so callers can change a card's loans. Try: Add: "public final class; this.loans = List.copyOf(loans); getters only."
  • Notes and javadoc. The AI adds javadoc for every method and an explanation. Try: Add: "One code block, no comments, no text."

What a strong prompt includes

  • Asks for stubs
  • Bans records and Lombok
  • Asks for a defensive copy
  • Asks for final fields
  • Limits the reply

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