Question

This is follow-up on my question:

error in java basic test program

This is still confusing me.
So specific problem is:

I already have a package and directory done.
say com.learn.java.mypackage

$ pwd
.../com/learn/java/mypackage

and here I want to create a test program in the same package and execute it.

$cat TestPackage.java

package com.learn.java.mypackage;

public class TestPackage
{

public static void main(String args[])
{
System.out.println("Hello World\n");
}
}

$ javac TestPackage.java
// runs file

$ Java TestPackage


Exception in thread "main" java.lang.NoClassDefFoundError: TestPackage (wrong name: com/learn/java/TestPackage)

if java runtime wants to make sure that a file belonging to a package lives in the same named directory, it is true here. Then why does it still crib?

Answer 1

You should do java com.learn.java.mypackage.TestPackage from within the parent folder of com.

So if com‘s full path is /my/project/folder/com/... you should call java com.learn.java.mypackage.TestPackage from /my/project/folder

Pasted in from the chat:

You can use from anywhere java -cp /my/project/folder a.b.c.ClassName, which tells java to look for class ClassName found in the packages a.b.c, and the packages should be searched at the path: /my/project/folder