In theory you can use any Java class/library. However, in practice this can be quite painful, given the type conversions you'll have to do everywhere the two to

In theory you can use any Java class/library. However, in practice this can be quite painful, given the type conversions you'll have to do everywhere the two touch. There are 'implicit' conversions for many base types, but when it gets a bit more complex, you'll have to write your own conversions, especially from Scala->Java.