Question

I wrote a simple hello world program to test the JDK installation. I can compile from Vim using:

:!javac Desktop\HelloWorld.java

That works just fine but when I try to run the program using:

:!java Desktop\HelloWorld

it gives me this error:

C:\Windows\system32\cmd.exe /c java “Desktop\HelloWorld”
Exception in thread “main” java.lang.NoClassDefFoundError: Desktop\HelloWorld (w
rong name: HelloWorld)
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$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)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
Could not find the main class: Desktop\HelloWorld. Program will exit.

The program works just fine from the normal command line.

C:\Users\Casey\Desktop>java HelloWorld
Hello world!

How can I execute the program from Vim without having to switch to the standard cmd?

Answer 1

java doesn’t take a file name as its first non-option argument. Instead it should specify the main class name (with .s between package names and class name, if there were any packages other than a default). Use -classpath to specify where to load classes from (with directories separated with your OS’s directory separator character (\)).

:!java -classpath Desktop HelloWorld