Re: [R] Using Java methods in R

From: Mike Marchywka <marchywka_at_hotmail.com>
Date: Sat, 23 Apr 2011 16:17:25 -0400



> From: marchywka_at_hotmail.com
> To: hill0093_at_umn.edu; r-help_at_r-project.org
> Date: Sat, 23 Apr 2011 15:12:30 -0400
> Subject: Re: [R] Using Java methods in R
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> > Date: Sat, 23 Apr 2011 05:32:59 -0700
> > From: hill0093_at_umn.edu
> > To: r-help_at_r-project.org
> > Subject: Re: [R] Using Java methods in R
> >
> > No answer to my post,
> > so let's try a simpler question. Am I doing this correctly?
> > I have the RGui with R Console on the screen.
> > On rhe top pullDowns, Packages > Install Packages > USA(IA)> rJava
> > > library(rJava)
> > > .jinit()
> > > qsLin <- .jnew("C:/ad/j/CalqsLin")
> > Error in .jnew("C:/ad/j/CalqsLin") :
> > java.lang.NoClassDefFoundError: C:/ad/j/CalqsLin
>
> i haven't used rjava yet, I think I installed it on linux
> for testing but no real usage, but this message
> appears to come from jvm probably because you
> specified an aboslute path. You can try this from
> command line,
>
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> $ ls ../geo/dayte*
> ../geo/dayte.class
>
> mmarchywka_at_phlulap01 /cygdrive/c/d/phluant/duphus
> $ java ../geo/dayte
> Exception in thread "main" java.lang.NoClassDefFoundError: ///geo/dayte
> Caused by: java.lang.ClassNotFoundException: ...geo.dayte
> at java.net.URLClassLoader$1.run(Unknown Source)
> at java.security.AccessController.doPrivileged(Native Method)
> at java.net.URLClassLoader.findClass(Unknown Source)
> at java.lang.ClassLoader.loadClass(Unknown Source)
> at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
> at java.lang.ClassLoader.loadClass(Unknown Source)
> Could not find the main class: ../geo/dayte. Program will exit.
>
>
> you want to search for the classpath and set that up then
> refernce the class name not the path ( the class loader will follow
> the path looking for it ).
> Not sure how you do that in rjava under 'dohs but
> if you search for that term is should be apparent.
> And of course 'dohs and pdf aren't always friendly
> for automated work so get something like cygwin and
> reduce pdf's to text etc.
>
>

It appears that by default the current directory is on the classpath. I must have installed this on 'dohs before and if I copy the class file into R directory it can find it,

> library("rJava")
> .jinit()
> .jnew("foo")
Error in .jnew("foo") : java.lang.NoClassDefFoundError: foo
> .jnew("dayte")

[1] "Java-Object{dayte_at_1de3f2d}"
>

that's unlikely to fix all your problems, you want to set the classpath but if you know the term and can load cygwin you should be able to find the way to set that up.

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> >
> > So I got this error which means I don't understand very much.
> > I go to C:/ad/j and get
> > C:\ad\j>dir CalqsLin.class
> > Volume in drive C has no label.
> > Volume Serial Number is 9A35-67A2
> > Directory of C:\ad\j
> > 04/23/2011 07:11 AM 14,651 CalqsLin.class
> > 1 File(s) 14,651 bytes
> > 0 Dir(s) 104,257,716,224 bytes free
> >
> > Just to show my intentions,
> > I had next wanted to call this java function method:
> > linTimOfCalqsStgIsLev("201104052359599999",-4) using:
> > > dblTim <-
> > > .jcall(qsLin,"D","linTimOfCalqsStgIsLev","201104052359599999","-4")
> > but that will probably also be wrong?
> > Obviously I don't understand.
> >
> >
> > --
> > View this message in context: http://r.789695.n4.nabble.com/Using-Java-methods-in-R-tp3469299p3469848.html
> > Sent from the R help mailing list archive at Nabble.com.
> >
> > ______________________________________________
> > R-help_at_r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help_at_r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
                                               



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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Sat 23 Apr 2011 - 20:21:35 GMT

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