implementing an interface java newbie
<p>I am a newbie in java and I am trying to implement an interface.</p>

<p>So main class </p>

<pre><code>public interface Matrix{
    //returns number of rows
    int numRows();
    //returns number of columns
    int numColumns();

    int addRows(...);
    ....
}
</code></pre>

<p>Now basically what I am trying to solve is lets say.. I have two matrices <code>matrixa</code> and <code>matrixb</code> of type <code>Matrix</code>.</p>

<p>I want to basically extend the matrix row wise.
So if <code>matrixa</code> had 10 rows and <code>matrixb</code> has 2 rows.
Then I want to return <code>matrixa+=matrixb</code></p>

<p>(offcourse assuming that number of columns are same.)</p>

<p>What is the right way to do this?</p>
