Re: JDK 9 RFR of JDK-8068948: Update java.base module to use new try-with-resources statement

[Ivan Gerasimov]

Hi!

A useful change!
Might it also make sense to allow anonymous variables in the 
try-with-resource statement?
So that something like `try (() -> System.out.println("closed")) {}` 
would work...

Would it make sense to also patch 
jdk/src/java.base/windows/classes/java/io/FileDescriptor.java in a 
similar manner, as it appears to contain the exactly same code?

Sincerely yours,
Ivan

On 14.01.2015 5:46, joe darcy wrote:
Hello,

Earlier in JDK 9, a language change was made so that if a resource for 
a try-with-resources statement is already final or effectively final, 
a new resource variable does *not* need to be declared to manage the 
variable.

The java.base module should take advantage of this language feature.

I've run an experimental checker for such locations over the base 
module and found one candidate where the new language feature can be 
used; please review this patch for it:

diff -r d873f6a7d16b 
src/java.base/unix/classes/java/io/FileDescriptor.java
--- a/src/java.base/unix/classes/java/io/FileDescriptor.java Tue Jan 
13 14:33:54 2015 -0800
+++ b/src/java.base/unix/classes/java/io/FileDescriptor.java Tue Jan 
13 18:40:54 2015 -0800
@@ -214,7 +214,7 @@
         if (!closed) {
             closed = true;
             IOException ioe = null;
-            try (Closeable c = releaser) {
+            try (releaser) {
                 if (otherParents != null) {
                     for (Closeable referent : otherParents) {
                         try {

The build succeeds with this change and the java.io.FileDescriptor 
regression tests pass.

Thanks,

-Joe