title: What does the unsafe operations compiler error mean?
body: <p>What does this error mean?</p>
  
  <pre class="lang-none prettyprint-override"><code>Note: Main.java uses unchecked or unsafe operations.
  Note: Recompile with -Xlint:unchecked for details.
  </code></pre>
  
  <p>Any suggestions how to avoid that kind of error?</p>