Program won't run

Question

I am currently reading "Sam's teach yourself Java 2 in 21 days", and I followed the instructions for programming the "VolcanoApplication" (the files can be found here http://www.cadenhead.org/book/java-21-days/chapter.php/1 and are called VolcanoRobot and VolcanoApplication). I compiled the two programs, but VolcanoApplication won't run. I get an error message saying "Exception in thread "main" java.lang.NoClassDefFoundError: volcanoapplication/class"

Answer 1

I copied the two files, compiled them and had no problem running VolcanoApplication. To try to narrow down your problem, do the following:
1. Check the names of both files to make sure that they are called VolcanoApplication.java and VolcanoRobot.java. 
Make sure there are no typos because the file name must exactly match the class name.  This includes case.
2. Before trying to recompile, first erase the old .class files.  Go to the directory that contains the files
and issue the command: "javac VolcanoApplication.java".  This should compile both files. 
The javac command should complete with no errors.  Now check your directory, you should see
VolcanoApplication.class and VolcanoRobot.class in your directory.
3. From the same directory, issue the command "java VolcanoApplication".  Again, make sure there are no typos. 
It should execute the program and print out some stuff.