JRuby file not run when executing from jar file (was: System.out.println not working from jar file)

Question

(Crossposted at JRuby Forum, but posted here again because I did not get any answer yet).

Platform: jruby 9.0.4.0 (2.2.2) 2015-11-12 b9fb7aa Java HotSpot(TM) 64-Bit Server VM 24.79-b02 on 1.7.0_79-b15 +jit [Windows 7-amd64]

Main program in Java, calling JRuby code via RedBridge Core. Java classes are in a Jar-File.

This setup works, as long I don't insist that the Ruby code is also executed from within the Jar-File, instead of being searched inside the file system. If I run the code from a Jar-File, the JRuby stdout seems to have disappeared.

First, here is the WORKING case:

// My main program (Jmain.java):
import vp.VP;
public class Jmain {
  public static void main(String[] args){
    System.out.println("Jmain started");
    VP vp = new vp.VP();
    System.out.println("vp instance created");
    vp.run();
    System.out.println("Jmain terminating");
  }
}

// My VP class (VP.java):
package vp;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.RubyObject; 
import org.jruby.embed.ScriptingContainer;
import org.jruby.embed.LocalContextScope;
import java.util.*;
public class VP {
  private ScriptingContainer container;
  public VP() {
    container = new ScriptingContainer(LocalContextScope.SINGLETHREAD);
  }
  public void run() {
    RubyObject asahi =
        (RubyObject)container.runScriptlet( 
            org.jruby.embed.PathType.RELATIVE,"rbsrc/bridge.rb");
    System.out.println("scriptlet executed");
  }
}

# My Ruby program rbsrc/bridge.rb
puts "Entering bridge" # Just to see what's going on
File.write("out.txt","This file was created by bridge.rb\n")
# ... rest of the code not shown

:: I put everything into a jar file, including the Ruby files
:: (although I don't need them there yet).
jar cvfm jars\vp.jar .... rbsrc

:: The program is executed like this:
java -cp c:\jruby-9.0.4.0\lib\jruby.jar;jars\vp.jar Jmain

I see the result of all the println statements, and the file out.txt is created.

Now for the NON-WORKING case:

In the whole setting, I change ONLY ONE line: The invocation of bridge.rb becomes

RubyObject asahi = 
    (RubyObject)container.runScriptlet(
         org.jruby.embed.PathType.CLASSPATH,"bridge.rb");

That is, I replace RELATIVE by CLASSPATH, and drop the "rbsrc/". When I run this, I get no error message, I get the output of all the println statements, BUT I don't see the output of the 'puts' statement, nor is the file out.txt created!

Note that bridge.rb seems to be loaded correctly (if I change bridge.rb to a different name, I get an exception), but it doesn't seem to be executed.

How come?

UPDATE: My problem description was wrong! There is nothing wrong with stdout, but it seems that my JRuby code bridge.rb is not executed! runScriptlet returns null, and when I create a file inside the Ruby program, there is no file afterwards.

What am I doing wrong? I have all my JRuby files in one directory. I put them into my Jar file. I run it using jar -cp JARFILE MAINCLASS. What else is missing?

BTW, the whole example application can be found here. There is a readme.txt included.

Just an idea: Could it have something to do with the user that is executing the JAR file? With that I mean read/write rights in the OS. Or you could take a look at the environment variables. — Leon, Dec 08 '15 at 12:53
Try not to use relative path, because it might not gonna work inside the JAR package. — PatNowak, Dec 08 '15 at 13:07
Can you attempt executing something else in ruby file? Is it executed? — Nick Louloudakis, Dec 09 '15 at 11:57
@NickL. : Oops, you seem to be right. I now check the resulting RubyObj and see that ìt is `null`. Of course this changes the whole picture. BTW, I have uploaded my small example application (together with a `readme.txt` explaining how to run the example) [here](http://files.ronaldf.eml.cc/tmp/jr6.zip). Maybe you could have a look at it? — user1934428, Dec 09 '15 at 14:46
Make an attempt and give an absolute path to your .rb file. Does it work? Just wondering..... — Nick Louloudakis, Dec 09 '15 at 15:02
@NickL. : Since the rb file is located inside the jar file, I don't see how I could write an *absolute* path to it, but I picked up your idea and gave a relative path, i.e. `container.runScriptlet(org.jruby.embed.PathType.CLASSPATH,"rbsrc/bridge.rb");`, and in this case, the Ruby code will be executed! There is now a new problem, but this seems to be unrelated, so I will first research it first and, if necessary, open a new thread on it. — user1934428, Dec 10 '15 at 08:12
OK, this is great. I attempted to update my answer if you want to accept it, otherwise please suggest any changes on this. — Nick Louloudakis, Dec 10 '15 at 13:27

Nick Louloudakis · Accepted Answer · 2015-12-10T13:26:19.760

You said

I replace RELATIVE by CLASSPATH

You probably changed the setting where java should search for classes from a relative path to the CLASSPATH.

You probably have not set the correct CLASSPATH variable value for your jar files - meaning the place where java should check for extra classes (more).

Try

set classpath = .;yourFilename.jar;

Notice that the dot (.) stands for the current directory.

You can then attempt to execute it using the -jar parameter in your command prompt:

java -jar yourFilename.jar

If you don't have a manifest in your jar, attempt executing it using the -cp (or -classpath, which is identical) parameter to specify your class path implicitly.

java -cp foo.jar full.package.name.MyClassName

Now, as a second thought, I would check that the executing directory has the permissions for the jar execution and the file creation (write), just in case.

UPDATE: It seems out by what you describe, that the problem is finally not in the classpath - as you don't have any exceptions, but in the path you have set for the file.

I suggest that you check the relative path you have set for the file inside your application that has a correct reference (just the file name is not enough, as "rbsrc/bridge.rb" is a relative path inside the application folders and this should be kept even when changed the option from RELATIVE to CLASSPATH). The relative path is based on the application folder as root in that case.

Applying blind dislikes to the whole question and all answers is of no use. If you disagree, tell us why. If you just like to downvote others, SO does not seem an appropriate place for you, sorry. — Nick Louloudakis, Dec 08 '15 at 14:01
If the classpath would not have been set correctly, or if the manifest would have been missing, Java would not have found the classes and an error message would have resulted, so this can't be the case. — user1934428, Dec 08 '15 at 16:32
You don't get any errors in console? Does it execute properly? — Nick Louloudakis, Dec 08 '15 at 16:34

JRuby file not run when executing from jar file (was: System.out.println not working from jar file)

1 Answers1