title: Timestamp as unique ID
body: <p>Is there something wrong if i use </p>
  
  <pre><code>Long uniqueId = System.currentTimeMillis()/1000;
  
  String documentName = ""+ uniqueId;
  </code></pre>
  
  <p>as for example a document name?
  Unless the user has a wrong Date it will be always unique right?
  Or is there a better way to create always unique number values?
  The reason i use <code>Long uniqueId = System.currentTimeMillis()/1000;</code></p>
  
  <p>is because it has to be unique even if the user generates that document from another device without the same data which means that i cannot create and save unique values and simply add +1 to it.</p>