Why doesn't the following line compile? : <p>I am trying to create an arraylist which can contain any type of object by using a generic with an unbounded wildcard.</p>

<pre><code>ArrayList&lt;?&gt; params = new ArrayList&lt;?&gt;(); 
</code></pre>

<p>I do not understand why I receive the following error and I want to know where I am going wrong?</p>

<pre><code>  required: class or interface without bounds
  found:    ?
</code></pre>
