Covariant Return Types: Fruit Harvest (JavaBasics_Task_291_V0.1)

📖 Description

In Java, Covariant Return Types allow an overriding method to return a subtype of the type returned by the original method in the superclass. This project illustrates this using a "Basket" hierarchy. While a generic Basket provides a generic Fruit, a specialized AppleBasket is guaranteed to provide an Apple. This feature reduces the need for explicit type casting and makes the API of specialized classes much more intuitive and type-safe.

📋 Requirements Compliance

• Class Hierarchy: Established Fruit -> Apple and Basket -> AppleBasket relationships.
• Covariant Overriding: Redefined getFruit() in AppleBasket to return Apple instead of Fruit.
• Type Verification: Used the instanceof operator to confirm the runtime type of the returned object.
• Polymorphism: Demonstrated that a specialized return still satisfies the superclass contract.
• Clean Architecture: Strictly separated the domain entities from the HarvestLauncherApp.

🚀 Architectural Stack

• Java 8+ (Inheritance, Covariant Returns, Type Checking)

🏗️ Implementation Details

• Fruit / Apple: The data models representing the items being harvested.
• Basket / AppleBasket: The factory-like classes demonstrating method specialization.
• HarvestLauncherApp: The bootstrap class for verifying the harvest results.

📋 Expected result

Apple created

💻 Code Example

Project Structure:

JavaBasics_Task_291/
├── src/
│   └── com/yurii/pavlenko/
│                 ├── app/
│                 │   └── HarvestLauncherApp.java
│                 ├── basket/
│                 │   ├── applebasket/
│                 │   │   └── AppleBasket.java
│                 │   └── Basket.java
│                 └── fruit/
│                     ├── apple/
│                     │   └── Apple.java
│                     └── Fruit.java
├── .gitignore
├── LICENSE
├── TASK.md
├── THEORY.md
└── README.md

Code

package com.yurii.pavlenko.app;

import com.yurii.pavlenko.basket.applebasket.AppleBasket;
import com.yurii.pavlenko.fruit.Fruit;
import com.yurii.pavlenko.fruit.apple.Apple;

public class HarvestLauncherApp {

    public static void main(String[] args) {

        AppleBasket appleBasket = new AppleBasket();
        Fruit harvestedItem = appleBasket.getFruit();

        if (harvestedItem instanceof Apple) {
            System.out.println("Apple created");
        }
    }
}

package com.yurii.pavlenko.fruit.apple;

import com.yurii.pavlenko.fruit.Fruit;

public class Apple extends Fruit {
    // Specific apple properties
}

package com.yurii.pavlenko.basket.applebasket;

import com.yurii.pavlenko.basket.Basket;
import com.yurii.pavlenko.fruit.apple.Apple;

public class AppleBasket extends Basket {
 
    @Override
    public Apple getFruit() {
        return new Apple();
    }
}

⚖️ License

This project is licensed under the MIT License.

Copyright (c) 2026 Yurii Pavlenko

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files...

License: MIT