title: How to generate unique positive Long using UUID
body: <p>I have a requirement to generate unique Long ids for my database primary key column.</p>
  
  <p>I thought i can use <strong>UUID.randomUUID().getMostSignificantBits()</strong> but sometimes its generating some negative long also which is problem for me.</p>
  
  <p>Is it possible to generate only positive long from UUID ?There will be like billions of entries so i want that each generated key must be unique.</p>