title: Calculate days between two Dates in Java 8
body: <p>I know there are lots of questions on SO about how to get <code>Date</code>s in Java, but I want an example using new Java 8 <code>Date</code> API. I also know about the JodaTime library, but I want a method without relying on external libraries.</p>
  <p>The function needs to be compliant with these restrictions:</p>
  <ol>
  <li>Prevent errors from date savetime</li>
  <li>Inputs are two <code>Date</code> objects (without time, I know about <code>LocalDateTime</code>, but I need to do this with <code>Date</code> instances)</li>
  </ol>