Creating a player that can hold different items

Question

I am making a game using Java, LibGDX and Box2D. What would be the best way to create a player that can hold:

• no item
• one item from group A
• one item from group B
• one item from both groups

Items from group A can only be used to attack, and are held in the right hand.
Items from group B can only be used to defend, and are held in the left hand.

Should I add the item to the player class and render/update the item in the player class? Or is there any best way to this that I am not aware?

This is the best way I know how to do it:

I would also be interested in any design pattern that could be applied to this situation.

Answer 1

I'd say, don't sweat it. Your character's two hands are independent of one another, the two items groups have distinct interfaces and are meant to be used in different ways. Just use a properly-typed reference for each hand, there's no need for type erasure or fancy design patterns.

public class Player {

    private DefenceItem leftHandItem;
    private AttackItem  rightHandItem;

    // ...

    public void update() {
        // Update yourself

        if(leftHandItem != null)
            leftHandItem.update();

        if(rightHandItem!= null)
            rightHandItem.update();
    }

    public void draw() {
        // Draw yourself

        if(leftHandItem != null)
            leftHandItem.draw();

        if(rightHandItem!= null)
            rightHandItem.draw();
    }

    public void attack() {
        if(rightHandItem!= null)
            rightHandItem.attack();
    }

    public void defend() {
        if(leftHandItem != null)
            leftHandItem.defend();
    }
}

I've kept these simple void() methods for the example, but passing the required information around won't be problematic since all type information is preserved.