I've looked through many of the existing threads about this error, but still no luck. I'm not even trying to package a jar or use any third-party packaging tools. I'm simply running from within Eclipse (works great) and then trying to run the exact same app from the command line, in the same location it's built to (getting this error). My goal is to be able to zip up the bin folder and send it off to be run by someone else via a command line script. Some details:
It's a command-line app and I'm using the commons-lang-2.4.jar for string utilities. That is the file that cannot be located (specificaly "java.lang.NoClassDefFoundError: org/apache/commons/lang/StringEscapeUtils")
I have that jar in my lib folder and have added it to my build path in Eclipse via right-click "Build Path -> Add to Build Path"
The .classpath file looks correct and contains the reference to the jar, but I assume that file is only used by Eclipse (contains this line: <classpathentry kind="lib" path="lib/commons-lang-2.4.jar"/>)
Could this be related to the Eclipse working directory setting? I have some internal template files that I created that are under src/templates, and the only way I can seem to get those to be seen is by setting the project working directory to AppName/src. Maybe I should be putting those somewhere else?
Let me know if any additional info would help. Surely this is something simple, but I've wasted too much time on it at this point. This is reminding me why I originally left Java back in '05 or so...
A NoClassDefFoundError basically means that the class was there in the classpath during compiletime, but it is missing in the classpath during runtime.
In your case, when executing using java.exe from commandline, you need to specify the classpath in the -cp or -classpath argument. Or if it is a JAR file, then you need to specify it in the class-path entry of its MANIFEST.MF file.
The value of the argument/entry can be either absolute or relative file system paths to a folder containing all .class files or to an individual .jar file. You can separate paths using a semicolon ;. When a path contains spaces, you need to wrap the particular path with doublequotes ". Example:
java -cp .;c:/path/to/file.jar;"c:/spacy path/to/classes" mypackage.MyClass
To save the effort of typing and editing the argument in commandline everytime, use a .bat file.
Edit: I should have realized that you're using an Unix based operating system. The above examples are Windows-targeted. In the case of Unix like platforms you can follow the same rules, but you need to separate the paths using a colon : and instead of an eventual batch file, use a .sh file.
java -cp .:/path/to/file.jar:"/spacy path/to/classes" mypackage.MyClass
Are you specifying the classpath to java on the command line?
$ java -cp lib/commons-lang-2.4.jar your.main.Class
The classpath setting you are setting in Eclispe are only for the IDE and do not affect how you application is run outside the IDE. Even if you use the Eclipse Functionality to export your application as an executable jar file there is no out of the box way to package all the jars your application depends on.
If you have packaged you application into a jar file called myapp.jar then running a command like below will run the application with the jar you depend on, if you have more than one just add them separted by ; on Windows or : on Unix:
java -jar myapp.jar -cp .;c:/pathtolibs/commons-lang-2.4.jar
If you are just running the classes directly then either run the folder containing your .class files will also need to be on the path (though I assume it already is since you are able to run the program and get errors).
Consider File -> Export -> Runnable jar to create a jar file which can be invoked directly with
java -jar yourProgram.jar
There are several variants depending on your needs.
Eclipse does not move any of the jars in your classpath into the bin folder of your project. You need to copy the util jar into the bin folder. If you move it to the root of the bin folder, you might be able to get away without any classpath entries but it's not the recommended solution. See #BalusC's answer for good coverage of that.
Eclipse doesn't build executable java classes by default. Don't ask me why, but it probably has something to do with using their own tools.jar (somewhere in plugins/org.eclipse.core ?) so that Eclipse can run without a JDK.
You can usually go to your project bin directory and do:
java -cp . MyClass
But if you have external jars, Eclipse handles those internally in another weird way, so you'll need to add those too.
make sure your jar commons-lang-2.4.jar in classpath and not redudance.
I ever add jar file to my classpath, and have 2 file jar in my classpath. After I delete it, work smooth
Related
I have exported a jar file that I want to run the console. The code compiles and runs correctly in eclipse but I am having an issue running it from the console.
To me it looks like the referenced jar's I added via built path in the Eclipse project file and not being added to the export. If that is the case, how do I ensure that they do? If not, what am I doing wrong?
When you export your source code's class files to a jar using eclipse, only the .class files of your source are exported! Hence your exported jar file doesn't contain the referenced jars you mentioned in eclipse! Due to this, the error occurs while executing from command prompt.
Solution:
Take all the jar files required to execute the program, store it in the same directory as you store the exported jar file. Now while executing the java command, provide all the jar file's names in classpath field as following:
java -classpath .;JAR1.jar;JAR2.jar MainClass
Once you do this, your problem should be resolved!
The dependencies need to be on the classpath, i.e. run like this:
java -cp <path_to_jar1>;<path_to_jar2> -jar ScrumTimeCaptureMaintenence.jar
When running from the command line make sure any dependencies are set on the class path by listing them in the -classpath parameter
I've been wanting to make executable jar files with java lately. When executing my code with Eclipse it works perfectly. But when I use Eclipse to export the same code as a runnable jar, Most of my jars work except the ones that draw from separate source folders.
The jar will be made but when launched it will try and open and then just say to check to console for possible errors. I try and run the jar through the console with the command "java -jar test.jar". and It says it cannot access the jar. Any Ideas? Btw Im on a macbook pro osX. Thank you!!
picture of where my files are within eclipse
If you have a file you want to store in a jar and access from there, you don't really have a Java File any more. Look at Class.getResourceAsStream() and Class.getResource() - the first can give you an InputStream to the (used-to-be) file, the second returns a URL and can be used for things like images. Note that the file being accessed can be accessed relative to the package/folder location of the class or relative to a classpath root (by putting "/" at the front of the resource name ("/resource/funny.jpg")).
When you execute the jar from a command line, be aware that you have a thing called the "default directory"; it is a folder in which your commands execute by default. If your jar is not in the default directory, you have to specify a valid folder path to your jar to execute it.
This is more curiosity than a problem:
I was recently wondering if there was a way to run compiled Java applications without using the cmd or an IDE such as Eclipse. I use Eclipse, but it isn't very useful if you want to run the program independently. Can you save Java files in Windows Explorer so you can create a shortcut for them? If so, how? Is there some sort of special extension to the file? I've heard of .JAR files, but I'm not sure what they are. Can anyone tell me how to do it?
.JAR files are archives containing - amongst other things - your compiled classes and a manifest file. You may set the main entry point of your application in that manifest. See Setting an Application's Entry Point.
Normally if you double click a jar file in windows it will be opened by javaw.exe -jar <yourFile.jar>. javaw.exe will lookup the manifest and try start the main class defined there.
create the jar file for java application using following syntax jar -cvf .jar . then use javaw.exe -jar
I have recently just created Java project using Eclipse that requires 2 JAR files (phiget21.jar and the mysql.jar)
Everything works fine when running the programme in Eclipse, and I have noticed the the jar files are saved in a 'lib' folder.
I soon going to me moving the programme off my computer to be used on other machines, so I decided to create a batch file to compile all of the classes and then run.
However, I am having trouble with the locating of the jar files. In the batch file do I require a command something like: set classpath=.:..;mysql.jar:../phidget21.jar, before the compilation of the Java classes?
I have read that the dots (...) have something to do with directories but not entirely sure how to implement them.
My programme is currently saved in these locations:
Project/src/.java files (I have also put the .jar files in here as well as i thought this may make thing s easier)
Project/lib/ .jar files
Any help would be greatly appreciated!
while setting the classpath a single dot (.) means current directory. As you jar files are in current directory, you just need to go to your current directory using cd command in DOS prompt, then use
set classpath = .;filename.jar;another filename.jar
Here . represents current directory and semicolon separates each classpaths.
You can even set classpath of more than one jar files using wild card character * which can be read as all.
You need something like
java -classpath lib/foo.jar:. com.company.Program
you can also use wildcards since java 6. see here
so the above becomes
java -classpath lib/*:. com.company.Program
I've built a JAR file and it executes fine on my PC (XP) which has Eclipse installed. It also works on another PC, which also has Eclipse.
I've tried running it on another PC(XP) that does not have Eclipse. Though it contains the JDK and multiple JRE. The JAR file just does not execute by clicking or from the command prompt.
I am not entirely sure, but my best guess is the Environment Variables are not set properly. Here is the error I receive from the command prompt:
Exception in thread "main" java.lang.NoClassDefFoundError: ...
Any help would be appreciated.
It must be a CLASSPATH issue.
The stacktrace should also say which class it failed to find. Once you have that, then find which jar has that class. Then add that jar file to your classpath or add it to the classpath env variable.
This is likely a classpath issue as others have said.
One thing to note is how your jar is constructed. You have a number of options in the dialog for exporting a runnable jar;
Extract classes into jar
Zip dependencies into the jar - creates jar-in-jar-loader.jar inside the jar.
Place jars in a subdirectory next to the jar.
Depending on what you have chosen for this depends on how the jar will behave. If the classes are extracted, dependent classes not in the JDK should be on the classpath. I'd recommend this course of action as it is simpler.
Now, the question is - are you using a dependency on your classpath not in the build dependencies of the eclipse project? If so, it won't be packed with / zipped into / put next to the jar because eclipse doesn't know about it (but java will still find it on your system because it's on the classpath). Also, if you've saved an ANT script and updated the build path in eclipse, eclipse won't update that ANT script - that is generated once only.
Environment variables are not considered when invoking a jar file when clicking on it (equivalent to running javaw -jar your.jar).
I'm pretty sure that it doesn't work on your first PC outside of Eclipse either.