On Wed, 16 Oct 2024 14:55:34 GMT, Jan Lahoda <jlah...@openjdk.org> wrote:
>> Currently, running `java` without any parameters will lead to an output that
>> is a full `--help`, which is over 100 lines (on my computer at least), and
>> it feels overwhelming. And many people might actually want to run
>> JShell/REPL, not the `java` launcher, but it is difficult find out about
>> JShell.
>>
>> The proposal herein is to print a much shorter help, together with a pointer
>> to JShell, when the launcher does not know what to do. I.e. there is nothing
>> specified to start, and no option like `--help` is specified. In particular,
>> on my machine, it prints:
>>
>> $ java
>> openjdk 24-internal 2025-03-18
>>
>> Usage: java [java options...] <application> [application arguments...]
>>
>> Where <application> is one of:
>> <MainClass> to execute the main method of a compiled class
>> -jar <JarFile>.jar to execute the main class of a JAR archive
>> -m <module>[/<MainClass>] to execute the main class of a module
>> <SourceFile>.java to compile and execute a single-file program
>>
>> Where key java options include:
>> --class-path <class path>
>> a ":"-separated list of directories and JAR archives to search for
>> class files
>> --module-path <module path>
>> a ":"-separated list of directories and JAR archives to search for
>> modules
>>
>> For more details about this launcher: java --help
>> For an interactive Java environment: jshell
>>
>>
>> Hopefully, this may be easier both for people trying to run something, and
>> for people that are really looking for JShell.
>>
>> What do you think?
>>
>> Thanks!
>
> Jan Lahoda has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Adjusting the concise help as suggested: 'using main class of a JAR
> archive' and '<JarFile>.jar'/'<SourceFile>.java'
src/java.base/share/classes/sun/launcher/resources/launcher.properties line 49:
> 47: \ -classpath <class search path of directories and zip/jar files>\n\
> 48: \ --class-path <class search path of directories and zip/jar files>\n\
> 49: \ A "{0}"-separated list of directories, JAR archives,\n\
The usual way to express this is with the word i.e. comma-separated,
semi-colon-separated and colon-separated. Not sure if that is possible given
the way substitution happens here. Though you could do what the manpage does
i.e.
Specifies a list of directories, JAR files, and ZIP archives to search for
class files.
On Windows, semicolons (;) separate entities in this list; on other platforms
it is a colon (:).
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/21411#discussion_r1803929464
