Error “main class not found”

问题

All,

My classpath has been set to the following folder:

CLASSPATH = .;C:\Program Files\Java\jdk1.6.0_21\bin;C:\Program Files\Java\jdk1.6.0_21\bin\project

All my java files and class files are under project folder listed in CLASSPATH.

Yet I am getting the following error while running a DriverClass in project folder:

C:\Program Files\Java\jdk1.6.0_21\bin\project>java DriverClass
Exception in thread "main" java.lang.NoClassDefFoundError: DriverClass (wrong name: project/DriverClass)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClassCond(Unknown Source)
        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$000(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)
Could not find the main class: DriverClass.  Program will exit.

Can anyone please help me understand the reason here?

回答1:

You're inside the package. You should be sitting in the package root. Go one folder up.

cd ..

Then reexecute it using java project.DriverClass.

That said, you should prefer not to use the CLASSPATH environment variable. Yours is currently also invalid. There are spaces in unquoted pathnames. Also, the JDK/bin folder isn't supposed to go in the classpath. Just use the -cp argument like java -cp . project.DriverClass (while sitting in the package root folder).

回答2:

Try:

C:\Program Files\Java\jdk1.6.0_21\bin>java project.DriverClass

assuming your package is project

回答3:

After compiling if we get a main class not found error, It is simple try this set classpath=%classpath%;.; type this in cmd and run it..problem will be resolved

来源：https://stackoverflow.com/questions/3796508/error-main-class-not-found

标签

java

classpath