title: Java. UUID, how does it works
body: <p>
  <li>Does the <code>java.util.UUID</code> is unique in each file?</p>
  
  <p>For example:</p>
  
  <ul>
  <li>We have file <strong>IDFile1.java</strong>, generating here a random id, using <code>UUID.randomUUID().toString()</code>.</li>
  <li>And we have file2 with name <strong>IDFile2.java</strong>, which generates another id.</li>
  </ul>
  
  <p>Will this two file IDs collide with each other?</p>
  
  <p></li>
  <li>Is there any way to "turn back" used ID, generated from <code>java.util.UUID</code>, that will mean, this ID could be used again?
  </li></p>