Running java helloworld

Question

I tried to google this, went to oracle.com and read all the questions on this forum related to this. I wrote a simple "Helloworld" program

package helloworld;

public class Helloworld {
    public static void main(String[] args) {

        System.out.println("Hello World!");
    }
}

NetBeans compiles the source code into a .class file. I move that file to C:\MyJava

I try to run it by C:\MyJava> java -cp . Helloworld and all possible variations of such. I keep getting the NoClassDefFoundError: Helloworld (wrong name: helloworld/Helloworld).

To make sure. There's a question almost exactly like this (difference in "wrong name"). The solution to that question does not work in my case.

`package hello world` is an invalid package declaration, I assume you want `package hello.world;` instead. — Thomas, Jul 24 '12 at 08:50
C:\MyJava>cd helloworld then C:\MyJava\helloworld>java Helloworld .run it like this it will work where helloworld is your packagename.Copy the .class with package(folder). — Dangling Piyush, Jul 24 '12 at 08:51

score 7 · Accepted Answer · answered Jul 24 '12 at 08:51

7

You get the "wrong name" error because your class is in the package helloworld. Java expects you to provide the fully-qualified class name on the command line:

C:\MyJava> java -cp . helloworld.Helloworld

The directory structure must match the package structure. This means that you should have a directory C:\MyJava\helloworld that contains the class file Helloworld.class.

answered Jul 24 '12 at 08:51

Jesper

195,030
44
313
345

Jesper, thanks so much. I don't know if this was supposed to be obvious, but it sure wasn't to me. Thank you. – PBD10017 Jul 24 '12 at 09:13

score 6 · Answer 2 · answered Jul 24 '12 at 08:50

6

You need to tell it the package name (which is helloworld):

C:\MyJava> java -cp . helloworld.Helloworld

answered Jul 24 '12 at 08:50

Jon Lin

139,544
27
213
216

Thanks Jon Lin. Your answer is right as well. Jesper added the package/folder structure that needs to be present to run java. Thanks. – PBD10017 Jul 24 '12 at 09:14
you do not need to specify a classpath pointing to ".". This is default behaviour ;) – zip Jul 24 '12 at 09:47

score 0 · Answer 3 · edited May 23 '17 at 12:17

0

Below post is similar to your problem. I hope it guides you;

How do I run .class files on windows from command line?

edited May 23 '17 at 12:17

Community

1
1

answered Jul 24 '12 at 08:52

Ufuk Şengül

11
1

This is not an answer. Use comments..oh you dont have enough rep for comments – Undisputed007 May 01 '14 at 10:29

Running java helloworld

3 Answers3