sun.audio is undocumented Like other sun.* packages, it is undocumented and it might disappear. Java Media Framework is old It’s an optional package, not part of the SE and hasn’t been updated in a long time. Oracle has a page on it and it’s still available but, well, who knows what will happen to it. … Read more
As you will find repeated ad infinitum when learning about signal handling in Java, you are encouraged to avoid writing Java code that depends directly on signals. The general best practice is to allow the JVM to exit normally on ctrl+c and other signals by registering a shutdown hook instead. Handling signals directly makes your … Read more
Because they are internal APIs: they are subject to change in a undocumented or unsupported way and they are bound to a specific JRE/JDK (Sun in your case), limiting portability of your programs. Try to avoid uses of such APIs, always prefer a public documented and specified class.