javac classpath; where to compile from?

I would like to compile and execute (run) without changing directories.  
Currently, however, I get the following error:

thufir@[EMAIL PROTECTED]
 
thufir@[EMAIL PROTECTED]
 javac -cp src -d /home/thufir/java/build/ src/com/
web_tomorrow/CPTest2.java 
thufir@[EMAIL PROTECTED]
 
thufir@[EMAIL PROTECTED]
 java build.com.web_tomorrow.CPTest
Exception in thread "main" java.lang.NoClassDefFoundError: build/com/
web_tomorrow/CPTest
thufir@[EMAIL PROTECTED]
 
thufir@[EMAIL PROTECTED]
 



To get good output, only this seems to work:


thufir@[EMAIL PROTECTED]
 
thufir@[EMAIL PROTECTED]
 javac -cp . -d /home/thufir/java/build/ com/
web_tomorrow/CPTest2.java 
thufir@[EMAIL PROTECTED]
 
thufir@[EMAIL PROTECTED]
 cd ..
thufir@[EMAIL PROTECTED]
 
thufir@[EMAIL PROTECTED]
 cd build/
thufir@[EMAIL PROTECTED]
 
thufir@[EMAIL PROTECTED]
 java com.web_tomorrow.CPTest2 
Run CPTest2.main()
thufir@[EMAIL PROTECTED]
 
thufir@[EMAIL PROTECTED]
 



how can I do this without changing directories?


thanks,

Thufir