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From: Arne Vajhøj on 25 Mar 2010 20:15
On 25-03-2010 09:47, bugbear wrote:
> Stefan Ram wrote:
>> bugbear <bugbear(a)trim_papermule.co.uk_trim> writes:
>>> Well, one *could* create a script to invoke the compiler
>>> and runtime components sequentially, to give the effect
>>> you request, but I see little benefit.
>>
>> One benefit would be the possibility to use Java package
>> in command lines, such as Perl is used in, say,
>>
>> cat cljp | perl -pe 's/\n\nFrom/\nFrom /mg' | grep ...
>
> Yes - I understand the "idea" but question wether
> Java can (in practice) express anything very useful
> in one line.

The line would be too long to be useful.

Arne
From: SolutionMonkey on 26 Mar 2010 12:40
On Mar 25, 4:36 am, Thomas Pornin <por...(a)bolet.org> wrote:
> According to SolutionMonkey  <valuemon...(a)telus.net>:
>
> > I'm guessing you can't do this in java since there is a separate
> > compilation step, but I thought maybe there's a compile/execute tool
> > or option I'm unaware of.
>
> The Java compiler is itself written in Java, and can be invoked
> programmatically; since Java 6, the API for that is standard
> (javax.tools.JavaCompiler). Also, Java supports dynamic loading
> of classes, so what you look for is conceptually doable. It can
> be done entirely in RAM without using files; see for instance:
>    http://www.java2s.com/Code/Java/JDK-6/CompilingfromMemory.htm
>
> However, Java is not very appropriate for one-liners; the package,
> imports, class declaration, method prototypes... are somewhat huge
> and cumbersome when using a single command-line invocation. You
> may want to add some pre-processing.
>
> Also, note that :
>
> -- This requires a JVM with the Java compiler, i.e. a JDK. A mere JRE
> (what most people have, to run applets and applications) does not
> contain the Java compiler.
>
> -- The kick-start of a JVM and a compilation pass tend to be
> computationally expensive. I have tried; expect some delay (e.g. one
> second). For usual Java tasks this is not a problem, but for a
> command-line interface I expect something much more responsive. Such
> delays quickly become irksome.
>
>         --Thomas Pornin


Thanks for the info Thomas. I can see what you're saying about java
not being appropriate for one-liners. That's why I'm looking for
another tool that would (hopefully) make some assumptions about things
like package imports, etc. It was a long shot.

Thanks again.
From: SolutionMonkey on 26 Mar 2010 12:45
On Mar 25, 4:49 am, bugbear <bugbear(a)trim_papermule.co.uk_trim> wrote:
> SolutionMonkey wrote:
> > Hi:
>
> > Is it possible to compile and execute a bit of java code in one line?
> > I know its possible in dynamic languages like groovy.
>
> > e.g. groovy -e "println 'Hello World!' "
>
> > I'm guessing you can't do this in java since there is a separate
> > compilation step, but I thought maybe there's a compile/execute tool
> > or option I'm unaware of.
>
> Well, one *could* create a script to invoke the compiler
> and runtime components sequentially, to give the effect
> you request, but I see little benefit.
>
>     BugBear

Thanks BugBear. I thought about this possibility, but I'm trying to
avoid building a .java file altogether. So this solution doesn't fit
my need. Sorry, I wasn't specific about this.

Thanks again.
From: SolutionMonkey on 26 Mar 2010 12:50
On Mar 25, 4:52 am, Alessio Stalla <alessiosta...(a)gmail.com> wrote:
> On Mar 25, 5:08 am, SolutionMonkey <valuemon...(a)telus.net> wrote:
>
> > Hi:
>
> > Is it possible to compile and execute a bit of java code in one line?
> > I know its possible in dynamic languages like groovy.
>
> > e.g. groovy -e "println 'Hello World!' "
>
> > I'm guessing you can't do this in java since there is a separate
> > compilation step, but I thought maybe there's a compile/execute tool
> > or option I'm unaware of.
>
> > Thanks for your comments.
>
> BeanShell is a Java interpreter written in Java. I have never used it,
> but it might do what you ask.

Thanks Alessio. I'm aware of BeanShell (as I am with groovy). Although
I've never used BeanShell, I'm pretty sure it would fit my
requirement. The problem is that I'm looking for something that comes
with a standard JDK distribution. Otherwise, I would use groovy since
I'm quite familiar with it. Sorry, I wasn't specific about this.

Thanks again.
From: SolutionMonkey on 26 Mar 2010 12:57
On Mar 25, 5:15 pm, Arne Vajhøj <a...(a)vajhoej.dk> wrote:
> On 25-03-2010 09:47, bugbear wrote:
>
> > Stefan Ram wrote:
> >> bugbear <bugbear(a)trim_papermule.co.uk_trim> writes:
> >>> Well, one *could* create a script to invoke the compiler
> >>> and runtime components sequentially, to give the effect
> >>> you request, but I see little benefit.
>
> >> One benefit would be the possibility to use Java package
> >> in command lines, such as Perl is used in, say,
>
> >> cat cljp | perl -pe 's/\n\nFrom/\nFrom /mg' | grep ...
>
> > Yes - I understand the "idea" but question wether
> > Java can (in practice) express anything very useful
> > in one line.
>
> The line would be too long to be useful.
>
> Arne

Thanks Arne.

Yeah, I think this is the crux of the problem. A one-liner tool is
only valuable if you can write a succinct code snippet.

I was hoping there was a tool in the JDK that helps with this. I know
groovy and beanshell could be of assistance, but I don't think either
of these is packaged with the JDK.

Thanks again.
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