Java ???? ??? ???? ??? ??? ??? ???? ? ??????. ?? ?? ??? ??? ??? ??? ? ?? ???, ??? ? ?????? ???? ?? ???? ???? ??? ? ????. ? ????? ??? ?? ???? ???? ??? ?? ??? ???? ???? ??? ???? ???? ?????.

? ?????? ??? ??

Java ??? ???? ????. ? ??? ??? ?? ??? ??? ??? ? ????.

String[] fruits = new String[3];
fruits[0] = "Apple";  // Correct
fruits[1] = 123;      // Compile-time error

??? ??? ???? ????? ???? ???? ?????. ??? ???? ??? ??(???, ??, ??)? ?? ????? ???? ???? ?? ?? ??? ?????.

Generics? ?????? ??? ??? ??? ???? ???? ?????. ??? ?? Fruit ????? ??? ?????.

1??: ?? ??? ??

?? ??? ??? ?? ???, ??, ??? ?? ?? Fruit ???? ?? ???? ?????.

// Base class for fruits
public abstract class Fruit {
    private String name;

    public Fruit(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

// Specific fruit classes
public class Banana extends Fruit {
    public Banana() {
        super("Banana");
    }
}

public class Apple extends Fruit {
    public Apple() {
        super("Apple");
    }
}

public class Grape extends Fruit {
    public Grape() {
        super("Grape");
    }
}

???? ??? ??? ??

Fruit ???? name ?? ?? ??? ???? ??? ?? ??? ???? ?? ?? ??????. ?? ???? ? ??? ??? ??? ?? ?????? ? ?? ? ????. ?? ???? ?? ??? ?????!

2??: ?? ???? ???

?? ?? ???? ????? ?? ?? ??? ?? ? ?? ???? ???? ShoppingCart ???? ??? ?????.

import java.util.ArrayList;

public class ShoppingCart<T extends Fruit> { // Restricts to Fruit and subclasses
    private ArrayList<T> items = new ArrayList<>();

    public void addItem(T item) {
        items.add(item);
    }

    public void removeItem(T item) {
        items.remove(item);
    }

    public void displayItems() {
        for (T item : items) {
            System.out.println(item.getName());
        }
    }
}

T extends Fruit? Fruit ?? ? ?? ??? ??? ? ??? ?? ?? ??? ?????.

3??: ???? ??

?? ????? ShoppingCart? ??? ????? ???????.

public class Main {
    public static void main(String[] args) {
        ShoppingCart<Fruit> fruitCart = new ShoppingCart<>();

        // Adding fruits
        fruitCart.addItem(new Banana());
        fruitCart.addItem(new Apple());
        fruitCart.addItem(new Grape());

        // Displaying contents
        System.out.println("Shopping Cart:");
        fruitCart.displayItems();

        // Removing an item
        fruitCart.removeItem(new Apple()); // Removal based on object equality (equals() can be overridden)
        System.out.println("\nAfter removing Apple:");
        fruitCart.displayItems();
    }
}

???? ??

1. ?? ???: ?? T? ?? ??? ?? ??? ??? ? ????.
2. ???: ??? ?? Fruit ??? ???? ????? ????.
3. ??? ??: ?? ???? ???? ???? ?? ??? ??? ?????.

??

? Fruit ?? ??? ShoppingCart ?? Java ???? ???? ???? ?????. ???? ?? ???? ?? ???? ???? ?? ??? Java ????? ?? ?????.

? ????

• Java ?? ??
• ???? Java(Joshua Bloch)

? ?? ?????

• ????
• ???
• ?????

? ??? Java? ??? ??: ??? ?? ???? ??? ???? ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!