No X11 DISPLAY variable was set, but this program performed an operatio n which requires it.
at java.desktop/java.awt.Graph icsEnvironment.checkHeadless (GraphicsE nvironment.java:166)
at java.desktop/java.awt.Windo w.(Window.java:553)
at java.desktop/java.awt.Frame .(Frame.java:428)
at java.desktop/java.awt.Frame .(Frame.java:393)
at java.desktop/javax.swing.Sw ingUtilities$SharedOwner Frame.(S wingUtilities.java:1919)
at java.desktop/javax.swing.Sw ingUtilities.getSharedOwnerFrame(Swing Utilities.java:1995)
at java.desktop/javax.swing.JO ptionPane.getRoot Frame(JOptionPane.jav a:1695)
at java.desktop/javax.swing.JO ptionPane.showOptionDialog(JOptio .java:874) ne ↓
at java.desktop/javax.swing.JO