Trajdosv2

public abstract class Item {
    private String name;
    private double weight;
    private double value;

    public String getName()   { return name;   }
    public double getWeight() { return weight; }
    public double getValue()  { return value;  }

    public void setName(String name)     { this.name = name;     }
    public void setWeight(double weight) { this.weight = weight; }
    public void setValue(double value)   { this.value = value;   }
}

public abstract class Container extends Item {
    private Item[] content = new Item[0];

    public Item getItem(int index) { return content[index]; }
    public void addItem(Item item) {
        //Dorzuć nowy przedmiot do tablicy
        int numberOfItems = content.length;
        Item[] tempContent = new Item[numberOfItems+1];
        for (int i = 0; i < numberOfItems; ++i)
            tempContent[i] = content[i];
        tempContent[numberOfItems] = item;
		content = tempContent;

        //Zwiększ wagę kontenera
        double currentWeight = getWeight();
        double newWeight = currentWeight + item.getWeight();
        setWeight(newWeight);
    }
}

//Dwie klasy do testowania
public class Rock extends Item {
    public Rock(double weight, double value) {
        setName("Rock");
        setWeight(weight);
        setValue(value);
    }
}
public class Chest extends Container {
    public Chest(double weight, double value) {
        setName("Chest");
        setWeight(weight);
        setValue(value);
    }
}

public class Main {
    public static void main(String[] args) {
        Container chest1 = new Chest(10, 20);
        Container chest2 = new Chest(15, 20);
        Item rock1 = new Rock(5, 0);
        Item rock2 = new Rock(5, 0);

        chest1.addItem(rock1);
        chest2.addItem(rock2);
        chest1.addItem(chest2);

        System.out.println("Waga chest1: " + chest1.getWeight());
    }
}