Hello,

Perhaps I don't completely understand what is required here, but I have tried to place all my classes inside a package named com.mycompany.lesson5

I understand that this particular lesson/example was supposed to have all its classes placed in 'default'. When placed in 'default', the program runs and behaves as expected.

Out of curiousity, I tried rewriting the whole thing and placing the classes into the package mentioned above. It compiles and Runs just fine from within the IDE, giving the error message "Sample usage of the program... etc" since understandably, args[] is empty.

However, running from the command line (and this time, having to browse deeper in than bin... actually bin/com/mycompany/lesson5) gives some error message. I have since deleted the project, but I will redo it shortly just so I can update this post with the error message presented.

This is obviously related to the classes being in a package... is anyone able to explain this?

A little update:

It seems that this isn’t specific to lesson 5.
I wrote Hello World again, this time placing it within a package.
It runs fine from the IDE, but when I use the console/command prompt and navigate into the specific folder with the .class file… typing in “java HelloWorld” will give the following error:

Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorld (wrong nam
e: com/mycompany /lesson1/HelloWorld)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(Unknown Source)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknow n Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$000(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
Could not find the main class: HelloWorld. Program will exit.

Again, if I didn’t place the class within a package and simply left it at default, the program will run from the console/command prompt. Why is this so?

Hi,

I'm new to Java, and I've been following the video tutorials and reading the book to get a grasp on the language. However, while trying to do the Lesson 5 try it, I keep running into an error that's preventing me from running the program in the command prompt. I can run it using the Java Application, and I get the print line "Sample usage..." but in the command prompt it keeps saying that it could not find the main class (I would attach a picture of the error if I knew how). I double checked the TestTax.class pathway and see nothing wrong. I'm I missing something or simply doing something wrong? Please help, I'd greatly appreciate it. Thank you.

I'm having the noclassdeffounderror also.

Google searches haven't helped at all. Lots of suggestions, but nothing that seems to work.

Java programs work fine from within Eclipse, but if I try to run them from cmd, error.

Hello, everybody.

I downloaded the solution for lesson 5, Lesson5Solution.zip, from here:
http://code.google.com/p/practicaljava/downloads/list

It uses I successfully ran the program from the command line using:

java -classpath C:\Eclipse\Cristina\workspace\Lesson5\bin com.practicaljava.lesson5.tryit.TestTax

TestTax.class and Tax.class are located in C:\Eclipse\Cristina\workspace\Lesson5\bin\com\prac ticaljava\lesson5\tryit.
If I issue the command from C:\Eclipse\Cristina\workspace\Lesson5\bin, I need not include the -classpath option anymore, as follows:

C:\Eclipse\Cristina\workspace\Lesson5\bin>java com.practicaljava.lesson5.tryit.TestTax

Hope this helps.