Runtime error

[i3130002]

Using JDK21 on PopOS

~/Android/sdk/AndroidGUI$ java id/dhipo/AndroidGUI
[GTK look and feel - com.sun.java.swing.plaf.gtk.GTKLookAndFeel] not supported on this platform
Exception in thread "AWT-EventQueue-0" java.awt.HeadlessException: 
No X11 DISPLAY variable was set,
or no headful library support was found,
but this program performed an operation which requires it,

	at java.desktop/java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:166)
	at java.desktop/java.awt.Window.<init>(Window.java:553)
	at java.desktop/java.awt.Frame.<init>(Frame.java:428)
	at java.desktop/java.awt.Frame.<init>(Frame.java:393)
	at java.desktop/javax.swing.JFrame.<init>(JFrame.java:180)
	at id.dhipo.AndroidGUI.<init>(AndroidGUI.java:129)
	at id.dhipo.AndroidGUI$1.run(AndroidGUI.java:159)
	at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:773)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:720)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:714)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:400)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:87)
	at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)