5.5 How to build a collection of class files or an entire package

When your class X uses another class Y in a different file then you need to add to the build target of your Makefile which is initially like so:

to what follows:

If your class Y is in another package such as the class ~/jtw-tutorials/path/to/dir/Y.class i.e. in the package path.to.dir then you need to add to the build target of your Makefile like so:

This process should be repeated for every class that is called, directly or indirectly from your main class X. By applying this process to every file in your package, you can build an entire package, simply by invoking the Makefile command make build. To actually compile and run the X class, let ~/jtw-tutorials/path2/to/dir/X.class be the location of the X class. Then you need to invoke the following Makefile target:

The build target calls the "clean" target which deletes all *.java and *.class files directly or indirectly in the folder ~/jtw-tutorials. If you don’t do this then java might run an old version of *.class files despite earlier errors in the build process. This is because the use of pipes in building and executing *.class files hides the return values of the programs javac and java.