title: How to declare a 2d array to hold objects from multiple classes
body: <p>I have declared an array which stores objects of type Square as follows:</p>
  
  <pre><code>Square[][] square_array = new Square[15][15];
  </code></pre>
  
  <p>I also have a class called Ball. </p>
  
  <p>Is it possible to store Ball objects in the square_array? If so, how would I go about doing this?</p>
  
  <p>Cheers</p>