( Solved ) Exception in thread "main" java.awt.HeadlessException

:~$ java -jar ubnt-recovery-tool/ubnt-discovery-v2.3.jar
Exception in thread "main" java.awt.HeadlessException
at java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:173)
at java.awt.Window.<init>(Window.java:476)
at java.awt.Frame.<init>(Frame.java:419)
at javax.swing.JFrame.<init>(JFrame.java:218)
at com.oOOO.super.O0oO.<init>(Unknown Source)
at com.ubnt.discovery.Main.main(Unknown Source)

What does this error message mean? And how can I solve it ???

Open your terminal and install openjdk-6-jre

:~# apt-get install openjdk-6-jre

This work fine for my ubuntu 12.04

:~/ubnt-recovery-tool$ java -jar ubnt-discovery-v2.3.jar