Application to Run in Terminal? (Eclipse)

Question

Hi guys,
I am new to Eclipse and would like to create a java project which I can run from the linux (kubuntu) bash terminal.
I've used Netbeans before and building it simply creates a jar file in the dist folder then I can run java -jar HelloWorld.jar and voila it runs.
This doesn't seem to be as straightforward with Eclipse however! (or am I missing something?) Not to dwell too much on why I am choosing to use eclipse over netbeans,
I would really like to (need to, for more memory-intensive project later) get a simple HelloWorld app to run from the linux terminal.
The steps I have followed so far are to create a HelloWorld app in eclipse as follows:
1. Create a new Java application and in Project Layout selected "Use project folder as root for resources and classes"
2. Create a package 'org'.
3. Create a class HelloWorld.java inside org with the following code:
package org;
public class HelloWorld {
      * @param args
     public static void main(String[] args) {
          System.out.println("Hello World!");
}When I build and run the above project in Eclipse, it works fine.
But when running it in the bash terminal, I get the following error:
ltsmm@gertlx:~/eclipse/HelloWorld/org$ java HelloWorld
Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorld (wrong name: org/HelloWorld)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)I suspect it has something to do with package names and specified output directories during project
creation?
Having a .jar file to run in the end would be nice but not essential.
If anyone could provide a procedure / some advice for getting this relatively simple thing to work it would be much much appreciated!
Gert
eclipse/packages newbie

Answer 1

Thank you, Pkwooster!
Interestingly, the following works quite well:
ltsmm@gertlx:~/eclipse/HelloWorld$ java org.HelloWorld
Hello World!
ltsmm@gertlx:~/eclipse/HelloWorld$Can I ask why you think the classpath needs to be set when I am running 'java HelloWorld' in the same directory containing the class?
OK this works too, think I see how the classpath works(kind of!):
ltsmm@gertlx:~/eclipse$ java -cp HelloWorld/ org.HelloWorld
Hello World!
ltsmm@gertlx:~/eclipse$Ok the above is ok for a single project now. My (main) problem is referencing another project from within this HelloWorld project.
I have created another project called MyLib (intended as a common library) and created a package 'mycom' and within it a class called MyClass like this:
package mycom;
import java.lang.String;
public class MyClass {
     private String m_name = "";
     public MyClass(String name) { m_name = name; }
     public void showName() {
          System.out.println(m_name);
}Can I reference this project in eclipse from within HelloWorld in such a way that I can run it from the command line? (or even just in eclipse)
I tried the following:
1. Right click HelloWorld project and in Properties->Project references added the "MyLib" project.
2. Modified the HelloWorld class as follows:
package org;
import mycom.*;
public class HelloWorld {
      * @param args
     public static void main(String[] args) {
          System.out.println("Hello World!");
          MyClass obj = new MyClass("blue_obj");
          obj.showName();
}But it doesn't work - not even in eclipse:
"the import mycom cannot be resolved"
do I need to add some jar or something manually?
What I would like to happen when I click 'build' on HelloWorld project is the following (if possible - is this what Ant is for?)
- MyLib to be built into a jar file MyLib.jar
- the MyLib.jar automatically copied to the 'org' folder in HelloWorld (where those classes exist)
- then it should have access to the MyLib code, right? (and should be runnable in the terminal too?)
If this can be done with eclipse and/or an ant file this would be so great!
Help very much appreciated,
Gerry