This is a very common question and there are chances that this might be marked as Duplicate, but even after reviewing a lot of answers and posts from stackoverflow and other communities, the problem just doesn't solve.
I have created a Project in my NetBeans IDE 7.3 and I Build the Project to get the JAR file by pressing SHIFT+F11. The next step, I perform is through WinSCP I copy the JAR file from my Windows Machine to the directory (/home/pi) in Raspberry PI.
Now, I am in the directory in my Raspberry PI where the JAR file is present and in the terminal I run the command
java -jar ProjectFinal.jar
I get the error "Could not find or load main class".
The contents of my JAR are as shown below (in the form of directories):
lib (contains all the libraries)
META-INF (contains a MANIFEST.MF file and the contents looks fine) and the contents are shown below:
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.8.4
Created-By: 1.7.0_17-b02 (Oracle Corporation)
Class-Path: lib/super-csv-2.1.0.jar
X-COMMENT: Main-Class will be added automatically by build
Main-Class: projectfinal.ProjectFinal**
and finally projectfinal (contains all the class files). I tried to change the contents of the MANIFEST.MF file by following this link. But this couldn't help me either.
Please suggest me any ideas that could get me out of this. It could be really helpful. I can share the code if it is needed.
I am using JRE version 7.
Any questions/inputs/ideas is deeply appreciated.
Please help.
Thanks a lot in advance.
I don't know about NetBeans but Eclipse IDE has an option to export into a "Runnable JAR File" instead of a normal JAR file.
I had the same issue and it solved my problem.
If not then follow this:
The text file must end with a new line or carriage return. The last
line will not be parsed properly if it does not end with a new line or
carriage return.
Related
I exported an executable Jar file from Eclipse.
On Windows when I double-click the file, it executes properly. When I run it from command line with java -jar MyJar.jar it also works.
But when I upload that file on my linux VPS and try to run it there, I just get the error
Error: Could not find or load main class mypackage.MyClass
I tried many things like changing CLASSPATH, trying out different Class-Paths and Main-Classes in the MANIFEST.MF file, and even trying to execute the program from .class files without the jar container. But unfortunately nothing works.
Do you have any ideas? Or did you face the same problem?
EDIT:
Manifest:
Manifest-Version: 1.0
Class-Path: .
Main-Class: mypackage.MyClass
Name: about.html
SHA-256-Digest: 1fuYr0bu6NsJZCAmSom5QtnvnV0Cg8DwLn77Dd1Ql24=
Name: jfx8.cssext
SHA-256-Digest: b2p9PXeoxqnTdYgBFeKp3s7J9PajukOS3sGqyM4s36I=
I finally solved my problem!!
The problem was that no JavaFx runtime was installed on the VPS. Don't know why that caused that error. I rewrote the Application without JavaFx and now it works.
Thank you for all your help.
I have written a java application in eclipse and then I have made its runnable JAR file, but the problem is that the application is not opening when I click its JAR file to open it, but the application is opening and running perfectly when I open it in the eclipse, I have made the JAR file number of times again and again but I am facing the same issue every time, no error is shown when I click the JAR but it is not opening.
So please tell what can be the problem with the JAR file.
Any number of things can be wrong with a jar file that prevents you from being able to run it after you create it. Some things to check:
Do you have java associated with your jar file?
Did you specify a main class when you built your manifest?
Are there dependent library jars your application depends on that did not get added to the classpath? The manifest file in your jar file should tell you any additional classpath entries that were generated.
Do you get an exception when you run it from command line?
You can run it two ways:
java -cp [path to your jar] your.package.MainClass
java -jar [path to your jar]
See if any of these are your issue and it should point you to the solution to your problem.
When you generate a JAR file, it doesn't mean something is going to happen, maybe it is just a library you generated, a reusable module of the system, etc.
"JAR (Java ARchive) is a package file format typically used to aggregate many Java class files and associated metadata and resources (text, images, etc.) into one file to distribute application software or libraries on the Java platform." - Wikipedia
So, Make sure you have a main class in your manifest, for example:
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.7.1
Created-By: 16.3-b01 (Sun Microsystems Inc.)
Main-Class: com.example.MainClass
Class-Path: lib/lib1.jar lib/lib2.jar
When I try to open a .jar file by double-clicking it I get this message that "Could not find the Main Class", however it works when opening it with the command line.
I've been looking for a solution for some days, I found a lot of people asking the same questions, some of the answers I found suggest that the main class is not declared in the manifest.mf, however I checked it and it is declared, here is my manifest.mf
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.8.4
Created-By: 1.7.0_13-b20 (Oracle Corporation)
Class-Path:
Main-Class: my_pack.Mainprog
[empty line]
[empty line]
I tried to run the jar that NetBeans builds, also with the fat jar plugin for eclipse and always get the same error.
What I would do is:
Create a dummy project in your Netbeans and export it as a runnable jar. Then take your manifest and the dummy-project manifest and compare it.
Manifests are really a pain in the code. They need to be absolutely correct formatted. Take care on trailing whitespaces, missing/additional empty rows etc...
Maybe check the Java Version, you are using. Make sure, that your command line uses the same one, like setup in your environment variables. Maybe there are doubled declarations...
Which java.exe is associated with *.jar files in windows explorer? Try exactly THIS java.exe to run your jar from the CLI. Same issue then?
Good luck!
Ok, I have this file I use for debugging purposes while I'm writing some code. However, I am looking to speed up the process by packing it in an executable .jar file. I have been creating a jar file via eclipse, and attempting to run it as is.
The contents of the jar (Derivitave Quiz.jar) are as follows:
DerivQuiz.java
DerivQuiz.class
Meta-INF (empty folder)
pass.txt
Also, would I have to re-write it to use a non-command line output, such as Jpane/JOptionPane, instead of System.out.print()?
My current code works fine in Eclipse, but not after porting to a jar.
I think you are making this far too complicated, especially if you're flummoxed by a task as simple as creating a JAR file.
All you need is javac.exe and jar.exe that come with the JDK. Look at this tutorial to show you how to do it properly:
http://docs.oracle.com/javase/1.4.2/docs/tooldocs/windows/jar.html
I did have to change all my print statements to use JOptionPane.showMessageDialog() instead of System.out.print().
Upon further inspection, the jar was being created without a manifest file, not allowing the jar to run.
I fixed this by adding a manifest file under META-INF/manifest.xml, with the following code:
Manifest-Version: 1.0
Created-By: 1.6.0_27 (Sun Microsystems Inc.)
Main-Class: MCExploit
Adding this allows the jar to run flawlessly, in addition to the other adjustments I made.
Duffymo's answer is good. But let me add something: if you're using Eclipse, you simply go to File -> Export then choose 'Executable Jar', and it does it automatically. Here's a nice guide for doing it a few different ways (including with Eclipse):
http://viralpatel.net/blogs/2008/12/create-jar-file-in-java-eclipse.html
Jar available at http://dl.dropbox.com/u/10919879/roller.jar
After writing and testing my program with Eclipse's built-in run Utilities, I decided it was time to export and distribute. So I go to File>Export>Runnable JAR and designate the class whose main method I want to invoke. Everything seems to be going off without a hitch, until I try to actually run the JAR.
Error: Could not find or load main class C:\Users\Matt\Documents\My Dropbox\Publ
ic\roller.jar
Contents of roller.jar
dice/Roller$RollData.class
dice/Roller.class
META-INF/MANIFEST.MF
contents of META-INF\MANIFEST.MF:
Manifest-Version: 1.0
Class-Path: .
Main-Class: dice.Roller
What's going on, and how do I fix it?
It's not a problem with your jar. It's a problem with OS setting that launches jar files incorrectly. I don't know if currently on Windows after installing Java it will be correctly configured automatically and why it isn't on your system. It may require editing registry to set jar files to be launched with java -jar command.
You can use application that converts JARs to EXEs if you're going to distribute it only to users with Windows.