Plans are afoot to have Java 9 accommodate the GTK 3 GUI toolkit on Linux systems. The move would bring Java current with the latest version of the toolkit and prevent application failure due to mixing of versions.
The intention, according to a Java enhancement proposal on openjdk.net, would be to support GTK (GIMP Toolkit) 2 by default, with GTK 3 used when indicated by a system property. Java graphical applications based on JavaFX, Swing, or AWT (Advanced Window Toolkit) would be accommodated under the plan, and existing applications could run on Linux without modification with either GTK 2 or 3.