Cvičenie 4

Úlohy

• Začnite pracovať na projekte - môžete začať vytvárať základnú štruktúru projektu na základe špecifikácie.
• Môžete si vytvoriť základ (inicializáciu) testovacieho prostredia. (Postup je v rámci Prednášky 5 16:00 minúta)
• Konzultujte so svojím cvičiacim prácu na projekte

Java Úlohy

Download the skeleton files

Task 8 — Potions, Inventory & Error Handling

Decorator Pattern, Custom Exceptions, Generics & Lambda Expressions

Your RPG world from previous tasks is growing. Characters can fight, equip weapons, and level up — but what happens when a warrior drinks a healing potion mid-battle? What if someone tries to stuff a 51st item into a backpack that only holds 50? And what if a player attempts to heal a character that's already dead?

In this task you will extend the RPG system with four new concepts that are central to real-world Java development. You are given the core character classes fully implemented (from Task 6). Everything else you build from scratch — the description below guides you through the problems you need to solve and the design approaches you should use.

Important: Do not change method signatures or access modifiers in the provided files.

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What you must implement

Naming conventions

All your classes should be in package org.jikvict.tasks.exposed. Choose class names that clearly describe their purpose — the tests will look for names that follow standard Java conventions and match the concepts described above (e.g., a class implementing the decorator for healing boost should be named HealingBoostDecorator).

The exception classes should be named after the condition they represent: InvalidPotionException, InventoryFullException, CharacterDeadException.

The base potion class should be named BasePotion. The abstract decorator should be named PotionDecorator. The duration-extending decorator should be named DurationExtenderDecorator. The generic inventory class should be named Inventory.

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Design hints

• The abstract decorator should have a protected field for the wrapped potion, so concrete decorators can access it directly.
• Think carefully about how apply() works in decorators — the healing boost decorator needs to both delegate to the wrapped potion and add its own extra healing.
• The Inventory class has nothing potion-specific in it. It works with any type T.
• findAll and findFirst should use the ItemFilter<T> interface, not java.util.function.Predicate. This is intentional — you should understand how functional interfaces work, not just use the standard library ones.
• Your exceptions are checked — this means methods that throw them must declare it in their signature, and callers must handle them.

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Submission

Take your whole project, remove unnecessary files (like .idea folder or build folder) and zip it.

The final zip file should contain the default-structure folder at the root.