title: How to update a value, given a key in a hashmap?
body: <p>Suppose we have a <code>HashMap&lt;String, Integer&gt;</code> in Java.</p>
  
  <p>How do I update (increment) the integer-value of the string-key for each existence of the string I find?</p>
  
  <p>One could remove and reenter the pair, but overhead would be a concern.<br>
  Another way would be to just put the new pair and the old one would be replaced.</p>
  
  <p>In the latter case, what happens if there is a hashcode collision with a new key I am trying to insert? The correct behavior for a hashtable would be to assign a different place for it, or make a list out of it in the current bucket.</p>