title: Best collection to use with type Double as key
body: <p>I have this object:</p>
  
  <pre><code>Public Cactus{
      Public Double key;
      Public String value;
  }
  </code></pre>
  
  <p>I have about ~100 <code>Cactus</code>, which all have a unique key, and a value that has some duplicates.
  I will however have to retrieve the value for a key about ~2000 times.
  My <code>Key</code> values varies between -10 and 280.</p>
  
  <p>I want this process to be as quick as possible. What would be the best approach for this? I was thinking using a  <code>HashTable</code>, although I always used one with <code>Integer</code> and not <code>Double</code>, and for some reason I am worried that it's not good practice to use <code>Double</code> as <code>Key</code>.</p>
  
  <p>Given my scenario, which collection would be the best to use?</p>