Java: How to code for items to inherit raw materials' properties?

Question

I am a Java beginner. My problem is, for example:

• Fire: DMG +1
• Stone: DEF +1

By combining to:

• Fire-stone: fire + stone, and inherit both their properties (DMG 1, DEF 1).

• Flame: fire + fire, and inherit 2 fire properties (DMG +2).

I've played around with classes and interfaces but doesn't seem to work. It seems to me that Java doesn't support multiple inheritance but multiple interfaces. I wonder how I could code each class/interface for this to work?

public static int DMG, DEF = 0;
public static String DESC = "";

interface fire {
    DMG = 1; }

interface stone {
    DEF = 1; }

class firestone implements fire, stone {
    DESC = "Born in fire and stone";
    //DMG and DEF calculations
}

Answer 1

You better use composition, here is what you could do:

public class Main {
public static void main(String[] args) {
    Tool firestone = new Tool(new Fire(), new Stone());
}

private static interface Component {
    int getDmg();
    int getDef();
}

private static class Fire implements Component {
    @Override
    public int getDmg() {
        return 1;
    }

    @Override
    public int getDef() {
        return 0;
    }
}

private static class Stone implements Component {
    @Override
    public int getDmg() {
        return 0;
    }

    @Override
    public int getDef() {
        return 1;
    }
}

private static class Tool implements Component {
    List<Component> components;
    int dmg;
    int def;

    public Tool(Component... component) {
        components = new ArrayList<>();
        components.addAll(Arrays.asList(component));
        dmg = 0;
        def = 0;
        for (Component c : components) {
            dmg += c.getDmg();
            def += c.getDef();
        }
    }

    @Override
    public int getDmg() {
        return dmg;
    }

    @Override
    public int getDef() {
        return def;
    }
}}

My implementation may be an overkill :P but it is extendable and you add more components that are more and more complicated.