title: JAR installer that auto-detects if Java is there and autostarts the application
body: <p>I need to build an installer that does the following:</p>
  
  <ol>
  <li>Installs my jar on the client.</li>
  <li>Auto-detects if JRE is installed (in which case it does not re-install it), otherwise installs it without the user clicking on another button.</li>
  <li>Auto-starts the application when the client is booted. </li>
  <li>Works across Windows, Mac and Linux.</li>
  </ol>
  
  <p>Any idea how to go about it?</p>