Quick question regarding pattern matching

[Brian Goetz]

On 3/23/2017 10:32 AM, Brian Goetz wrote:
> Without getting into the details -- I'd like to wait until a Patterns 
> JEP is proposed before doing so -- I'll give some quick overview answers.
>
> 1.  Yes, exhaustiveness is important.  The obvious tool there is 
> sealing, and sealed classes at the language level would really also 
> like sealing support at the VM level, which can be considered a 
> generalization of finality.  (Though, even with sealing at both the 
> language and VM level, there is still a possibility of being surprised 
> by separate compilation artifacts, since if the switch is in a 
> different class than the one in which the supposedly-sealed hierarchy 
> is defined, new subtypes can still be added, and if the client is not 
> recompiled, you will get a surprise.)  Stay tuned.

For the record, see this JEP (currently in draft): 
https://bugs.openjdk.java.net/browse/JDK-8046171