Hi, I'm a brand new newbie following this thread with great interest. I can run the "HelloWorldApp" just fine at the DOS command line; but, I want to learn to use NetBeans IDE. When I plug HelloWorldApp.java into NetBeans it compiles successfully into the same folder; however, when I try to run I get the above error message, followed by the encouragement "BUILD SUCCESSFUL" (no "HelloWorld" output, however). I've tried futzing around with the classpath stuff till I'm blue in the face! It can't be this hard! Any ideas?
Thanks

Guys, I finally got "HelloWorldApp" to work from within NetBeans IDE. It appears my problem was that I had put both HelloWorldApp.java and HelloWorldApp.class (from an earlier DOS prompt compile) directly into the project path. Therefore, when I ran the code within NetBeans I got a new "build" with only the compiled code, and not the source; I was confused because my original source and class file were still together in their original place - so I didn't understand why Java couldn't find the source. Anyway, I obviously have a lot to learn! If anyone can suggest a way I can clear up my considerable confusion about how this all works, I would be eternally gratefull!

hi i am getting this error too but i dont use command line (and dont plan to) im using textPad, and i installed it after i installed the jdk, so even after reading these helpful post i still dont understand where my problem is. the .java file is in the same folder as the .class. im not that new to java, but i've just begun to work at home and am unfamilier with setting up the editor and such to make it work (at school it was already good to go)

Hey all,
i'm kinda having this same problem.. in fact i'm just trying to run in the DOS prompt. Codings written for Applets (appletviewer sach.html ) run perfectly in dos prompt, after i set the Classpath n all.

But, a simple java program, gives me this same error , when i try to run using >>java Sach
after successfully compiling using javac..
Exception in thread "main" java.lang.NoClassDefFoundError: Sach

i set my classpath to the following
path=C:\Program Files\Java\jdk1.5.0_05\bin
(btw, i guess this sounds correct ya? coz ,well the javac command works fine. It doesn't even give any compile errors).

i hope someone can help me out plz. it's really confusing..

Regards,
Sachitha

It looks like you have set the PATH but NOT the CLASSPATH.

For CLASSPATH - just put a period in as the variable. Really. It's weird, but it works.

If you're not sure how to do this, let me know.

Good luck!


PS You might want to try to install JCreator instead - it's free, and you don't have to do all this nonsense - I don't think.

i set the PATH and CLASSPATH using the following link which was posted in this page itself
(http://www.cs.ucsb.edu/~teliot/Path_and_Classpath.htm )
but that's for jdk 1.5.0_02, but i'm having jdk 1.5.0_05...
i gave for the CLASSPATH a . (a fullstop)
Now how do i run programs in the Command prompt???
i just did like this...
javac <program>.java //now this worked without a problem

when i gave
java <program> //it gives the following error

Exception in "main" java.lang.UnsupportedClassVersion error
....etc etc...

plz tell me wut i should do , n why do i get such an error...

hey i kinda figured out a way to run simple java program (like hello world..)
set classpath=.
set path=.......\bin

but this program with packages n all wont work.. it compiles , but cant run
can someone plz tell me why???
i get the following error when i start to run with java command

Exception in thread "main" java.lang.NullPointerException

why is that?

My command prompt doesn't recognize neither CLASSPATH nor JAVA_HOME commands...I've already set the path variable but when i'm goiong to set the classpath and java_home variables it says that they are not recognized as an intern or extern command etc...
Could anyone please help me?

(I'm portuguese; sorry for my english...)

type 'set CLASSPATH' and 'set JAVA_HOME' instead. CLASSPATH and JAVA_HOME are not commands they are system varables.

(You also should have stared your own thread instead of adding onto this one.)