java interface methods usage : <p>Hi I have been given the following interface and I need to implement bag using this interface, I'm a little confuse as how to use the methods, any help/hint would be appreciated. I need to add items to the bag and it should be able to accept duplicate items. Then I have remove an item and find an item.</p>

<pre><code>public interface Things&lt;T&gt; extends Iterable&lt;T&gt; {
    public int size();
    public boolean add(T x);
    public T remove(T x);
    public T find(T x);
    public void clear();
}
//Implementing thing using bag
public class Bag&lt;T&gt; implements Things&lt;T&gt; {

    @Override
    public int size() {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public String add(T x) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public String remove(T x) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public String find(T x) {
        // TODO Auto-generated method stub
        return null;
    }

}


public class ThingsDemo {


    public static void main(String args[])

    {
        How to I use add(), remove(), and find method here?


    }

}
</code></pre>
