title: How to get a specific key or value from a ConcurrentHashMap
body: <p>I honestly tried to look at a lot of posts but I am not sure what is the correct way of getting a specific key from a ConcurrentHashMap.</p>
  
  <ol>
  <li>How to get the first key in a ConcurrentHashMap?</li>
  <li>How to get the key on first encounter of a certain value?</li>
  <li>How to update the value of a specific key?</li>
  </ol>