java -jar  Whist-Online.jar
Exception in thread "main" java.awt.HeadlessException:
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
        at java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:159)
        at java.awt.Window.<init>(Window.java:317)
        at java.awt.Frame.<init>(Frame.java:419)
        at javax.swing.JFrame.<init>(JFrame.java:194)
        at com.truyens.whist.client.gui.StartScreen.<init>(StartScreen.java:53)
        at com.truyens.whist.client.gui.ScreenFactory.makeScreen(ScreenFactory.java:59)