title: Hashtable rehash on remove
body: <p>Does anyone know why the java jdk implementation of hashtable does not rehash the table upon remove ?</p>
  
  <p>What if space usage is too low? Isnt it a reason to reduce size and rehash?</p>
  
  <p>Just like load factor 0.75 which triggers rehash on put, we could have a lower bound like 0.25 (of course analysis can be done on the best value here) on the  density of the table and trigger the rehash again, provided the size of the table is greater than the initialCapacity.</p>