Question

I have a jar called GameClient.jar which has a main method. And I have a json.jar which does contain an org/json/JSONException.class

Both of these are in the dist folder.

I run the following
java -classpath dist/json.jar -jar dist/gameclient.jar

Not really sure why I still get

Exception in thread "main" java.lang.NoClassDefFoundError: org/json/JSONException
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
    at java.lang.Class.getMethod0(Unknown Source)
    at java.lang.Class.getMethod(Unknown Source)
    at sun.launcher.LauncherHelper.getMainMethod(Unknown Source)
    at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)

Caused by: java.lang.ClassNotFoundException: org.json.JSONException

I am on Windows XP and Java 1.7. I get the same error with or without the classpath option.

Answer 1

From the java documentation:

-jar

Execute a program encapsulated in a JAR file. The first argument is the name of a JAR file
instead of a startup class name. In order for this option to work, the manifest of the JAR
file must contain a line of the form Main-Class: classname. Here, classname identifies the
class having the public static void main(String[] args) method that serves as your appli-
cation’s starting point. See the jar(1) and the Jar trail of the Java Tutorial @
http://java.sun.com/docs/books/tutorial/jar for information about working with Jar files
and Jar-file manifests.

When you use this option, the JAR file is the source of all user classes, and other user
class path settings are ignored.

So your gameclient.jar must include all of the user classes that you need. The classpath setting is ignored. Just create the gameclient.jar to include the classes in json.jar.