I would highly appreciate your help with a ClassNotFoundError while calling a Java method from RPG. This happens when any other user, except me, tries to run my program.
It literally seems a problem with CLASSPATH or access to jar files but I tried from that aspect too.
Explanation:
I have an RPG program which calls a java method in a jar file. My CLASSPATH has the right jars included (JtOpen jar files). It works perfectly when I run the RPG program from a Green and Black screen (Iseries session manager). Where as it throws the following error message whenever another user tries to run it the same way:
RPG Procedure received Java Exception java.lang.NoClassDefFoundError: com.ibm.as400.access.AS400 when calling method "invokeApiPgm" with signature "([Ljava.lang.String;Ljava.lang.String;I[Ljava.lang.String;)Z" in class "callIceApi.CallIceApiPgm".
The signature above is also the same as that of the method i call. Does the class the Java is complaining seem to be that of AS400 or could it be mine? I can see that the AS400 class is available as public. The class object was created successfully by the constructor of my class. It just fails when calling the main method invokeApiPgm.
What do you think I am missing or messing up with, guys?
Thanks for your help!
Tewelle
How about a CL program that explicitly sets the classpath and then calls your RPG program?
The CLP:
PGM
ADDENVVAR ENVVAR('CLASSPATH') VALUE('.:/dir1:/dirA/dirB:/javaToolkit/jt400.jar') LEVEL(*JOB)
CALL PGM(MYLIB/MYPGM)
ENDPGM
This page may also be helpful.
In the beginning I had all Jars and files in the same outer Jar which I exported from Eclipse and adding the Jar's path to my CLASSPATH couldn't work for me. However, I don't know why though, it worked after taking the JT400.Jar separately out and then including its path in the CLASSPATH, as Benny's answer, with another separate inclusion to the main project jar worked right.
Thanks Benny!
Related
I have spent all last night (until 3am) and this morning researching, testing, refactoring, and attempting to debug this issue. I have a simple Java game in Netbeans and while it runs perfectly perfect within the IDE in either run or debug mode, once exported into a jar file it refuses to load any resources corrrectly. There are many similar questions to this such as this one regarding loading an ImageIcon and despite great effort none of these solutions work for my project. I am not using ImageIcons, only simple BufferedImages and wav sound files. I recently refactored to combine my BufferedImageLoader and Sound classes into one Resource class, which I then moved into the same package as all my resources even though it worked perfectly well in a separate code package before in the IDE, although it works in its new location as well, strictly within the IDE.
I'm rather irritated and flustered from this issue. The truly infuriating thing is that this project used to work with resources after being exported into a jar, and now it seems to have stopped working with no changes. The only real programmatic difference between back when it worked and now is that I didn't have or use sound files back then, but this error isn't related to the sound files, as it catches an exception (and generates an error dialog) just from first trying to load the art assets.
I've tried every possible solution I've found in my research to no avail. Hopefully a fresh set of eyes can reveal the error of my ways.
The offending line of code is
return ImageIO.read(Resource.class.getResource("/res/" + imageFileName));
whereas imageFileName is the parameter with values passed from method calls such as
blockSheet = Resource.loadImage("art_assets/platform.png");
The location of the Resource class seemed to have no bearing on this working within Netbeans. My res folder is inside src, next to the com class package beginning.
It throws an IllegalArgumentException: input == null! exception. After some testing it seems that Resource.class.getResource("/res/" + imageFileName) returns a null value, which makes no sense at all. Again, this works perfectly perfect within the IDE. I can change the jar file into a zip and look inside to see that all the resources are exactly where they should be with the correct names and the correct extensions.
Here is a zip file of my entire project. Any help is immensely appreciated. Thank you.
EDIT:
Some of the things I've already tried:
getResourceAsStream() instead of getResource()
classLoader() between Resource.class and getResource()
this.getClass() instead of Resource.class from a non-static context
I think this should help:
How to get the path of a running JAR file?
CodeSource codeSource = YourMainClass.class.getProtectionDomain().getCodeSource();
File jarFile = new File(codeSource.getLocation().toURI().getPath());
String jarDir = jarFile.getParentFile().getPath();
provided by Benny Neugebauer in the post.
So i have been working on my Project1 and For some reason i cant figure out why It wont run. I get the Error "Could not find the main class". What am i doing wrong?
My code is:
https://gist.github.com/anonymous/6604f427cc9d17391478
I'm not sure how to post all the code properly with out making it super confusing (I tried to figure it out earlier) But let me know if i can help!
Is there something wrong with my code? Or do i need to compile it in a certain way?
if your using eclipse, goto to run configurations, select:
Project: my Project1
Main Class: assignment1.Assignment1_test
this will work for sure :)
Let's say you have a folder/package assignment1 somewhere on your file system inside which you have your Assignment1_test and Fraction class.Refer the screenshot above to compile and run your code. :)
You have it in a package named assignment1. This means it is in a folder named assignment1. After compiling, go up to the folder that contains assignment1 then run java assignment1.Assignment1_test from there.
java expects a fully-qualified class name (the name of the class including the package). It also expects that the class is in your classpath (. is implicitly added). Packages are tied directly to the directory structure.
Combining that all together, since the full-qualified name assignment1.Assigment1_test must be specified to java, and since the package structure is the directory structure, then the class is expected to be in assignment1\ relative to the current directory and therefore you must be in the directory that contains assignment1 to execute it (unless it is somewhere else in your classpath, which, given your situation, I'm guessing is not the case).
I have been searching the web trying to find the answer to my question, but everywhere I look seems to have too complex of a solution for a beginner like me. I have been working on this project, and just now realized that I should've made a package, or something like that. The thing is though, my program was working fine until I started dabbling with it, and now it won't work at all. I am getting this error:
Exception in thread "main" java.lang.NoClassDefFoundError: BubbleSort. class
Caused by: java.lang.ClassNotFoundException: BubbleSort.class
at java.net.URLClassLoader.findClass(URLClassLoader.java:434)
at java.lang.ClassLoader.loadClass(ClassLoader.java:672)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:358)
at ``java.lang.ClassLoader.loadClass(ClassLoader.java:638)
Could not find the main class: BubbleSort.class. Program will exit.
Here's how my "path" looks, if I am not mistaken. I am connected to my school's Z: drive through a remote connection, and from there I have a folder called myFirstname_Lastname_A4,
which then leads me to another folder called sortingzz which I believe is supposed to have only my source files, but it also ended up with my class files in there whenever I compiled. So here's what I am doing to compile.
cd myFirstname_Lastname_A4/sortingzz
javac *.java (Works fine, this is where I end up with my Class files inside of my sortingzz folder)
java * (This is where I get the error)
I am pretty sure I am just trying to run the program wrong. Before I started messing around with stuff I wasn't ready for, I used to just run the file with my main function in it, like this
javac SortingImplementation.java
java SortingImplementation
And that for the most part worked fine, but I started having trouble calling certain classes from other classes, so thats when I found out I was suppose to do the packaging and importing stuff.
In case that is the issue, I have on the top line of every source file:
package sortingzz;
and I am importing like this:
import sortingzz.*;
This is correct, right?
UPDATE:
I decided to give up on class pathing and trying to package everything, because as usual, I am getting responses that are way over my head, and to be honest I don't think it is necessary.
After removing package and importing from everything, and once again compiling using javac *., it actually compiles this time. However whenever I try to run my class with the main in it, SortingImplementation, it tells me that
Could not find the main class: SortingImplementation. Program will exit.
I don't get it, I am looking at the SortingImplementation.class right now, with all the other classes and java files, so I am not sure what it's trying to do.
javac *.java is fine. This will compile your files. However, you only need to run the file with your main method in it: java MainClass
You say that you are using packages to organize the classes. In this case you need to set the class path using the -cp flag.
javac -cp /path/to/parent/of/package classname.java
and
java classname
Also, your main class should be declared public and should have a main()
NoClassDefFoundError occures when a class was recognised in compile time but was not available during runtime.
So the JVM can't find your class in the classpath.
using -cp flag to specify where your package is should work.
the commanc javac *.java compiles all found java files to corresponding .class files. If you all your classfiles are in the same folder, which they should, you just run your regular java SortingImplementation command.
java * would, a bit depending on your OS, yield in an undesired command. For instance, on Linux it would be expanded by the OS to java SortingImplementation.java SortingImplementation.class BubbleSort. The last one is a directory, which ofcourse is not an executable class.
I've found several instructions on how to import user-built .class and .jar files to JPype, but I seem to be having a lot of trouble getting anything working at all.
What works: I can import standard java stuff and print HELLO WORLD and such.
Some of what I've tried:
I've tried adding -Djava.class.path with the path to a jar containing the relevant class files, to a directory structure containing (several folders down) the relevant .class files, as well as '-Djava.ext.dirs'. I've recompiled and re-installed with a different JVM location. The class I am attempting to instantiate is Outer, public, and has a public constructor.
I'm using Python 2.6.1 on OSX 10.6.
My current test file:
from jpype import *
startJVM(getDefaultJVMPath(), '-Djava.class.path=/Users/gestalt/Documents/msmexplorer_git/msmexplorer/MSMExplorer/build/classes')
java.lang.System.out.println("hello world")
msmexplorer = JPackage('org.joofee.meh.msmexplorer')
T = msmexplorer.MSMExplorer()
shutdownJVM()
If I use JClass I always get ClassNotFound exceptions from JPype; if I use JPackage I get Package not callable errors. Basically, JPype can't find my stuff.
Thanks so much!
EDIT (possibly helpful debugging stuff...):
Is there a straightforward way to print which third party java classes are available/imported?
Package not callable errors are referenced in this link) it would seem you need to make sure the java class file is accessible from the working directory. I am not sure how the jvm classpath comes into play, I would have thought how you did it would work.
You could also try loading the org package and then getting to the other packages through that one as the link I shared shows:
msmexplorer = JPackage('org').joofee.meh.msmexplorer
T = msmexplorer.MSMExplorer()
I have read the documentation and several websites on exactly how to do this, however Matlab does not seem to pick up the classes that I have added to the dynamic java class path. Nor do I use the right syntax to correctly construct the object.
I have an class HandDB and which to create an object of this type and invoke it's static methods to connect to a SQL database. The class has an empty constructor and takes no parameters. The class is part of a package 'nuffielddb' which I made in a project within Netbeans. All the files are on my usb stick which is my E:\ drive...
I would like to be able to use all the classes within the package. The package is contained at E:\nuffielddb.
I entered the following commands into Matlab:
javaaddpath('E:\');
javaclasspath; % Output from java class path includes E:\ within dynamic path
str = java.lang.String('Test'); % Works fine
db = nuffieldbd.HandDB(); % Does not work - undefined variable or class error
Interesting I typed 'import nuffielddb.*;' and received no error.
Just where am I going wrong?
Thanks for your help btw!
Ah problem solved! Well not solved in a sense! I found out it's actually a problem with my matlab installation and I have no idea how to fix it :-(
Never mind, it works on the computers at the office :-)
if your classes are in a .jar file, make sure your classpath includes the .jar file name itself (not just the directory it's in).
Also if the MATLAB JRE is Java 1.5 (R2006b is, whereas R2009a is Java 1.6, not sure when they switched), make sure your classes are compiled with 1.5 as a target, not 1.6, otherwise MATLAB will not be able to use them.
Minor note: .* imports will never error, so they're not diagnostic. They simply add a package to the list that Matlab searches through when trying to resolve a class name. Nonexistent packages are ignored.
>> import this.package.does.not.exist.*
>>