title: Use Guava Cache to persist data to a hard disk
body: <p>I am new to Guava Cache. How do I create the following in the cache?</p>
  
  <ol>
  <li>Save the data in memory as normal.</li>
  <li>When the size of the cache is over the given number, it will persist the data in cache in a configurable file on the hard disk.</li>
  </ol>