CODEWITHSUNDEEP
javaeclipsejar
user1998511
user1998511

Reputation: 465

java.lang.NoClassDefFoundError for Java Jar File

I'm trying to create a jar file for one of my Java files. However, once I create it and try to run it, I get a java.lang.NoClassDefFoundError.

I did the following to create the jar. The file is Worker.java and it's in src/beatDB.

jar cfm Worker.jar Manifest.txt src/beatDB

My Manifest.txt file is just

Main-Class: Main-Class: beatDB.Worker \n (with a new line afterwords)

When I run java -jar Worker.jar, I get this error.

Exception in thread "main" java.lang.NoClassDefFoundError:
beatDB/Worker
Caused by: java.lang.ClassNotFoundException: beatDB.Worker
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

However if I run java beatDB/Worker, the file runs fine.

Does anyone know how to fix this problem?

Upvotes: 0

Views: 2481

Answers (1)

Tarik
Tarik

Reputation: 11209

You should jar the manifest along with the .class files, not the .java files.

.java files contain the source code.

.class files contain the compiled code. For Java it is called byte code.

You want the package structure of your classes to be reflected in your jar file. If you have an Animal class under com.example, then your jar file should contain com/example/Animal.class

See How to create jar file with package structure? for the proper jar file package structure.

Upvotes: 1

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