title: Mac OS X-specific operations make application crash on other OS's despite checking for OS first
body: <p>I'm using the following code for integrating my Java app with Mac OS X:</p>
  
  <pre><code>if (System.getProperty("os.name").equals("Mac OS X"))
  {
      System.setProperty("com.apple.mrj.application.apple.menu.about.name", "JoText"); // Program name
      com.apple.eawt.Application.getApplication().setDockIconImage(new javax.swing.ImageIcon( JotextMain.class.getResource("icons/Icon.png")  ).getImage()); // Dock icon
      System.setProperty("apple.laf.useScreenMenuBar", "true"); // Use global menu bar
      com.apple.eawt.Application.getApplication().addApplicationListener(new MacAboutAndQuit()); //Make "Quit" and "About" options work
  }
  </code></pre>
  
  <p>On Mac OS X, it works fine. On Ubuntu however:</p>
  
  <pre><code>Exception in thread "main" java.lang.NoClassDefFoundError: com/apple/eawt/ApplicationListener
      at java.lang.Class.getDeclaredMethods0(Native Method)
      at java.lang.Class.privateGetDeclaredMethods(Class.java:2451)
      at java.lang.Class.getMethod0(Class.java:2694)
      at java.lang.Class.getMethod(Class.java:1622)
      at sun.launcher.LauncherHelper.getMainMethod(LauncherHelper.java:494)
      at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:486)
  Caused by: java.lang.ClassNotFoundException: com.apple.eawt.ApplicationListener
      at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
      at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
      at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
      ... 6 more
  </code></pre>
  
  <p>When I comment out that code, it launches fine on Ubuntu.
  Strange, because it checks for Mac OS X first before executing Mac OS X specific operations.
  I don't have Windows, but friend of me using Windows also reported my .jar didn't launch and gives a "A Java Exception has occured" message from the Java Virtual Machine Launcher instead. On a Windows PC at school, same problem.</p>
  
  <p>What's causing this?</p>