class loader error

[Gursewak Singh]

one of my friend has instaled java 7 when we compile a program it compile well but when we run it gives a error
"could not find or load main class Ab.class".
enviromental variable are set

[Jesper de Jong]

This is maybe because you are trying to run it with a command like: java Ab.class
You should instead be running it with: java Ab (without the .class).

The Java launcher expects a class name (Ab), not a filename (Ab.class).

[Ankush Kaundal]

Give the classpath using -cp argument and then try to run it.

Say if your class file is in D:\JavaPrograms folder then run it using java -cp D:\javaPrograms Ab

[Campbell Ritchie]

Disagree. It is most likely Jesper was correct.

[Ankush Kaundal]

Campbell Ritchie wrote:Disagree. It is most likely Jesper was correct.

That what is said by jesper is also right but still the system will not be able to find classpath of the program and then you have to use this argument.