title: How to create tmp file name with out creating file
body: <p>I write application in Java using SWT. I would like to create unique file name. But I do not want create it on hard drive. Additional functionality: I want to create unique file name in specify folder.</p>
  
  <pre><code>public String getUniqueFileName(String directory, String extension) {
          //create unique file name   
  }
  </code></pre>