How to solve java.lang.NoClassDefFoundError?

Question

I\'ve tried both the example in Oracle\'s Java Tutorials. They both compile fine, but at run-time, both come up with this error:

Exception in thread \"main\"         


        

Answer 1

if you got one of these error while compiling and running:

* NoClassDefFoundError

* Error: Could not find or load main class hello

* Exception in thread "main" java.lang.NoClassDefFoundError:javaTest/test/hello 
(wrong name: test/hello)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(Unknown Source)
        at java.security.SecureClassLoader.defineClass(Unknown Source)
        at java.net.URLClassLoader.defineClass(Unknown Source)
        at java.net.URLClassLoader.access$100(Unknown Source)
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)

-------------------------- SOLUTIION -----------------------

the problem is mostly in packages organization. You should arrange your classes in folders properly regarding to the package classifications in your source code.

On Compiling process use this command:

javac -d . [FileName.java]

To Run the class please use this command:

java [Package].[ClassName]