I created a JAR file from my java project.
Using Eclipse, I added a JAR as a referenced library in my own project.
However, now when I try to run my program's JAR using java -jar myProgram.jar, I get an exception stating that my referenced jar is not available.
So how can I create a JAR consisting a reference to a different JAR and make it work?
Right, an executable JAR cannot contain its own JAR dependencies.
You have to have the main class and classpath set in the executable JAR manifest, then package all your JAR dependencies along with the executable JAR in a relative directory structure that matches the manifest CLASSPATH. Reading this might help.
You need to use Eclipse's runnable JAR exporter. Since Eclipse 3.5 you've the following options when you rightclick project, choose Export > Runnable JAR file:
Either way, Eclipse should take care that you'll be able to run the JAR the way you want on the exported location.
See jarjar project. It is exactly what you are looking for. http://code.google.com/p/jarjar/
Related
I have been looking around for some time now, but didn't a find way how to export a JAR (not runnable jar) that contains in it's build path the referenced libraries.
Using Eclipse, I have included the lib folder which contains the jars of the referenced libraries in the export process.
Importing that JAR to another project and calling some method results in a ClassNotFoundException.
Looking at the MANIFEST, I didn't see any reference to those jars in the classpath, though the jars are indeed included in the jar.
So my questions are:
1. Is there any way to accomplish the packaging of the non-executable JAR so it will include libraries?
2. Is there any best practice for building and deploying a jar that include other jars libraries?
I tried it too but it doesn't work for me. I added the final .jar file but it doesn't work.
So, I did a workaround.
Extract the .jar file that you want as a dependency.
Copy that content and put it all inside your .jar file.
Add your .jar file as dependency inside an eclipse project.
Run it and see if everything is ok.
I made an executable jar that depends on other jars with the command prompt using the format
jar cvfm MyJarName.jar manifest.txt *.class dependentJar1.jar dependentJar2.jar
The jar was made properly and everything seemed fine... But when run, it gets runtime errors because it can't find the class files that my project refers to. Exploring the created jar, the other 2 jars that it depends on are in there just as they should be and they are listed in the manifest.mf class path, but for some reason java is dumb and doesn't actually look inside those jars.
When those 2 jars are in the same directory as the owner jar, java is able to find them and it works fine. But I don't want this; I want those jars to actually be INSIDE it. What's the deal? How can I make an executable jar with other jars inside it work?
You can use something like OneJar or jarjar (or any of several others) to pack up everything inside of a single jar.
If you're building with Maven you could use the Maven Shade Plugin.
You could use a custom classloader like JarClassLoader that will allow precisely what you want.
I don't think you could. Maybe it's somehow possible with customized classloader, but not from-the-box. Use maven shade plugin.
If you use an Ant Builder in Eclipse and put the referenced jars in a library accessible to your project, Eclipse will extract the necessary classes and include them in your distributable jar file.
I have a Java project in Eclipse with class MainClass having main method in package :
com.nik.mypackage.
The project also references two external libraries, which I copied in the lib folder in Eclipse and then added to build path using ADD JAR function. The libraries being one.jar and two.jar
This library is in lib folder in eclipse and added to the build path.
I want to create a executable JAR of the application using ant script. So that user can access my application using command:
c:>java -jar MyProject-20111126.jar
I know about the Eclipse plugin which directly exports a java application as runnable JAR. But I want to learn ant and the build process so manually want to create the build.xm.
You have two options from your build.xml. You can either unjar the library jars and then bundle their contents with the code compiled for your application. Or, you can put the library jars on the filesystem and supply a ClassPath entry in the manifest file of the MyProject-2011126.jar file.
If you set the classpath in the manifest remember that the path you supply is relative to the MyProject-2011126.jar.
one alternative:
Instead of having only a jar, you build mutiple jars (your jar + libs) +batch file.
So, your built package can be like this structure:
-/package/bin/app.bat
/package/lib/my.jar
/package/lib/one.jar
/package/lib/two.jar
In app.bat you just have the same as your code
java -jar MyProject-20111126.jar
PS: if you want to start learning built tools, ANT may be a bit tool old. I suggest http://maven.apache.org/
Please try one-jar. It helps to redistribute everything packaged as single jar and comes with ant-task . See Easiest way to merge a release into one JAR file.
I have created a program to connect to MySQL. I add Connector/j using eclipse add external jar option. Program works fine in eclipse. But when I created the executable jar using eclipse and when i run it, it always give ClassNotFoundException. Please tell me how to add external jars to my jar. Or is there any other error? Please can anyone help me.
The simplest solution is to export your project as a 'Runnable Jar file' (Right-click on project->Export...->Runnable Jar file) that will place all dependencies in one jar file.
Otherwise you will need to include a classpath to the additional jars either in the manifest.mf file or on the command line with the -cp option.
java -cp .;myjar.jar;mysql.jar my.package.classname
You need to create a jar that includes the files from all the dependent jars. The classloader won't be able to find the classes if you simply include the jar files themselves inside the executable jar. There is an eclipse plugin called FatJar that does this.
http://fjep.sourceforge.net/
You can simply add the class-path element to your jar MANIFEST and list your external jar inside the MANIFEST
like this:
Manifest-version:1.0
Class-Path: class0.jar
class1.jar
class2.jar
class3.jar
class4.jar
...
One jar per line.
I have a Java project that utilizes Jython to interface with a Python module. With my configuration, the program runs fine, however, when I export the project to a JAR file, I get the following error:
Jar export finished with problems. See details for additional information.
Fat Jar Export: Could not find class-path entry for 'C:Projects/this_project/src/com/company/python/'
When browsing through the generated JAR file with an archive manager, the python module is in fact inside of the JAR, but when I check the manifest, only "." is in the classpath. I can overlook this issue by manually dropping the module into the JAR file after creation, but since the main point of this project is automation, I'd rather be able to configure Eclipse to generate properly configured JAR automatically. Any ideas?
*NOTE*I obviously cannot run the program successfully when I do this, but removing the Python source folder from the classpath in "Run Configurations..." makes the error go away.
Figured it out, had to add the source folder with the Python module in it as a class folder in the Build Path project properties. Not sure if this next part is necessary or not, but since the module is not compiled, I added the folder again as "Attached Source" after adding the class folder.
Have a look at the maven-jython-compile-plugin and its demo project at http://mavenjython.sourceforge.net/ . It allows bundling jython with dependencies into a standalone jar.