What is the fastest way to know if a letter exists in a Character collection
<ol>
<li>Should I define a hashmap with something like "A" , new Character("A")</li>
<li>should I use something like a sorted list ? or cast it into an int? </li>
<li>simple list? (that doesnt seem too efficient )</li>
</ol>

<p>I need a fast retrieving - when I ask if the Char exists.
adding time is almost none important. </p>
