— Scott McNealy, Sun Microsystems Chairman, President and ceo

590
 
chapter 17
%cd MyProject/classes
%java com.headfi rstjava.PackageExercise
%cd MyProject/source
%javac -d ../classes com/headfi rstjava/PackageExercise.java
Compiling with the 
-d
(directory) fl ag
tells the compiler to put the 
compiled code (class files) 
into the classes directory, 
within the right package 
structure!!
Yes, it knows.
Now you have to specify 
the PATH to get to the 
actual source file. 
To compile all the .java fi les in the com.headfi rstjava 
package, use:
Running your code
run your program from 
the ‘classes’ directory. 
%javac -d ../classes com/headfi rstjava/*.java
Compiling and running with packages
When your class is in a package, it’s a little trickier to compile and 
run. The main issue is that both the compiler and JVM have to be 
capable of fi nding your class and all of the other classes it uses. 
For the classes in the core API, that’s never a problem. Java always 
knows where its own stuff is. But for your classes, the solution 
of compiling from the same directory where the source fi les are 
simply won’t work (or at least not reliably). We guarantee, though, 
that if you follow the structure we describe on this page, you’ll be 
successful. There are other ways to do it, but this is the one we’ve 
found the most reliable and the easiest to stick to.
MyProject
source
classes
101101 
10 110 1 
0 11 0 
001 10 
001 01 
PackageExercise.class
com
headfirstjava
com
headfirstjava
 
Lorper 
iure 
eugue 
tat vero