I have read check documentation: https://checkstyle.org/checks/xxxxxx/nameofaffectedcheck.html
I have downloaded the latest checkstyle from: https://checkstyle.org/cmdline.html#Download_and_Run
I have executed the cli and showed it below, as cli describes the problem better than 1,000 words
/var/tmp $ javac YOUR_FILE.java
/var/tmp $ cat config.xml
[Using standard `google_checks.xml`]
/var/tmp $ cat YOUR_FILE.java
package blim;
import java.util.HashMap;
public class Blim {
record Point(int x, int y) {}
void blim() {
var _ = new Thread();
switch ("foo") {
case String _ -> System.out.println("bar");
}
switch (new Point(0, 0)) {
case Point(int _, _) -> System.out.println("point");
}
try {
// something
} catch (Error _) {
// something else
}
for (var _ : new String[] {"foo"}) {}
var map = new HashMap<String, Integer>();
map.computeIfAbsent("foo", _ -> 23);
}
}
/var/tmp $ RUN_LOCALE="-Duser.language=en -Duser.country=US"
/var/tmp $ java $RUN_LOCALE -jar checkstyle-12.2.0-all.jar -c config.xml YOUR_FILE.java
Starting audit...
[WARN] /private/tmp/Blim.java:5:1: Missing a Javadoc comment. [MissingJavadocType]
[WARN] /private/tmp/Blim.java:9:9: Local variable name '_' must match pattern '^[a-z]([a-z0-9][a-zA-Z0-9]*)?$'. [LocalVariableName]
[WARN] /private/tmp/Blim.java:11:19: Pattern variable name '_' must match pattern '^[a-z]([a-z0-9][a-zA-Z0-9]*)?$'. [PatternVariableName]
[WARN] /private/tmp/Blim.java:14:22: Pattern variable name '_' must match pattern '^[a-z]([a-z0-9][a-zA-Z0-9]*)?$'. [PatternVariableName]
[WARN] /private/tmp/Blim.java:18:20: Catch parameter name '_' must match pattern '^[a-z]([a-z0-9][a-zA-Z0-9]*)?$'. [CatchParameterName]
[WARN] /private/tmp/Blim.java:21:14: Local variable name '_' must match pattern '^[a-z]([a-z0-9][a-zA-Z0-9]*)?$'. [LocalVariableName]
[WARN] /private/tmp/Blim.java:23:32: Lambda parameter name '_' must match pattern '^[a-z]([a-z0-9][a-zA-Z0-9]*)?$'. [LambdaParameterName]
Audit done.I would not expect any warnings here (except the javadoc one).
Quoting what I wrote on the related #16768:
Hi, I'm one of the maintainers of Google's Java style guide (cited above). The situation is that this guide is a copy of Google's internal style guide. Internally, we do not yet support a version of Java that allows _ in place of an identifier. We are probably not going to update the guide to mention _ explicitly until we do. However, I would argue that even as written, the guide does not preclude _ lambda parameters. Sections 5.1 and 5.2 are respectively "Rules common to all identifiers" and "Rules by identifier type", but _ is not an identifier, it is a keyword. So the guidelines in 5.1 and 5.2 don't apply to it.
When Google does internally support _, we will update the guide to say that _ is allowed everywhere it is legal. That change will probably be in Section 5.1.
So I think it would make sense to update the rules without waiting for an explicit change to the guide. I believe it would just involve updating all of LambdaParameterName, CatchParameterName, LocalVariableName, and PatternVariableName so that the regex changes from ^[a-z]([a-z0-9][a-zA-Z0-9]*)?$ to ^(_|[a-z]([a-z0-9][a-zA-Z0-9]*)?)$.
I have read check documentation: https://checkstyle.org/checks/xxxxxx/nameofaffectedcheck.html
I have downloaded the latest checkstyle from: https://checkstyle.org/cmdline.html#Download_and_Run
I have executed the cli and showed it below, as cli describes the problem better than 1,000 words
I would not expect any warnings here (except the javadoc one).
Quoting what I wrote on the related #16768: