This is an automated email from the ASF dual-hosted git repository.
sunlan pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/groovy.git
commit 496312a20747fd779eca049aa264fdbb1d40685e
Author: Daniel Sun <sun...@apache.org>
AuthorDate: Wed Jan 15 14:46:20 2020 +0800
Add docs for try-with-resources
---
src/spec/doc/core-semantics.adoc | 57 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)
diff --git a/src/spec/doc/core-semantics.adoc b/src/spec/doc/core-semantics.adoc
index f6ac125..bfcc72c 100644
--- a/src/spec/doc/core-semantics.adoc
+++ b/src/spec/doc/core-semantics.adoc
@@ -288,6 +288,63 @@ try {
}
----
+==== ARM Try with resources
+
+Groovy often provides better alternatives to Java 7's `try`-with-resources
statement for Automatic Resource Management (ARM).
+That syntax is now supported for Java programmers migrating to Groovy and
still wanting to use the old style:
+
+[source,groovy]
+--------------------------------------
+class FromResource extends ByteArrayInputStream {
+ @Override
+ void close() throws IOException {
+ super.close()
+ println "FromResource closing"
+ }
+
+ FromResource(String input) {
+ super(input.toLowerCase().bytes)
+ }
+}
+
+class ToResource extends ByteArrayOutputStream {
+ @Override
+ void close() throws IOException {
+ super.close()
+ println "ToResource closing"
+ }
+}
+
+def wrestle(s) {
+ try (
+ FromResource from = new FromResource(s)
+ ToResource to = new ToResource()
+ ) {
+ to << from
+ return to.toString()
+ }
+}
+
+def wrestle2(s) {
+ FromResource from = new FromResource(s)
+ try (from; ToResource to = new ToResource()) { // Enhanced
try-with-resources in Java 9+
+ to << from
+ return to.toString()
+ }
+}
+
+assert wrestle("ARM was here!").contains('arm')
+assert wrestle2("ARM was here!").contains('arm')
+--------------------------------------
+Which yields the following output:
+--------------------------------------
+ToResource closing
+FromResource closing
+ToResource closing
+FromResource closing
+--------------------------------------
+
+
=== Power assertion
Unlike Java with which Groovy shares the `assert` keyword, the latter in
Groovy behaves very differently. First of all,
