title: How to detect if a file is not utf-8 encoded?
body: <p>In Java, how can a file be tested that it's encoding is definitely not utf-8?</p>
  
  <p>I want to be able to validate if the contents are well-formed utf-8.</p>
  
  <p>Furthermore, also need to validate that the file does not start with the byte order mark (BOM).</p>