The good old Oracle Forms UI does not look really cool. Of course, you can use nice icons and choose the right colors, but the controls are not fancy compared to swing controls.
If you try to to migrate from Oracle Forms to Java, wouldn't it be great to migrate one screen after the other. Or better, create new screens with Java and integrate them in your existing Oracle Forms application. Use both technologies as long as is necessary.
Don't think that you have to migrate the whole Oracle Forms application, migrate step by step. It is absolutely possible to use your new screens in your Oracle Forms aplication or as separate application without Forms. Save time, money and don't replace your existing Oracle Forms developers.
You would like to see how this can look like?
The first screenshot shows a standard Java swing application, with a simple master/detail and some editors:
The next screenshot shows the same screen (without source code changes) used in an Oracle Forms application:
You are right, it is great to embedd the same Java screen, but the Look and Feel is not very cool. Do you know that Java has some nice LaF's? Here is the same screen with Nimbus Look and Feel: