#
# The following Makefile example includes instructions for how to compile three Java byte code class files, including:
#
# - definitions - some variables that contain useful definitions of commands and options to be run
# - rules - instructions for how to perform the builds of each target
# - cleanup - removing artifacts of the build so the next build starts from a clean slate
#

# a variable that defines the java compiler command to use
JCC = javac

# a variable that refers to compilation flags to be sent to the compiler
# the -g flag compiles with debugging information
JFLAGS = -g

# typing 'make' with no options from the command-line will, by default, invoke the first rule in the Makefile, here called 'default'.
# this rule defines the target, 'default', and the other targets upon which it depends
# this rule does not include any commands necessary to build the default target, only the other targets upon which this target depends in order to be complete
default: Average.class Convert.class Volume.class

# this rules defines the target named 'Average.class', which you'll notice is one of the dependencies of the 'default' target
# the Average.class target is dependent on the Average.java source code file
# this rule includes indendented commands below it, which outline the command-line operations to be performed to build this target
# by substituting the variables with their values, this command would look like 'javac -g Average.java'
Average.class: Average.java
        $(JCC) $(JFLAGS) Average.java

# this rule follows the same pattern as the previous rule
Convert.class: Convert.java
        $(JCC) $(JFLAGS) Convert.java

# this rule follows the same pattern as the previous rule
Volume.class: Volume.java
        $(JCC) $(JFLAGS) Volume.java

# the following rule is not invoked in a default build, since it is not required by the default rule
# in order to invoke the following rule, the command 'make clean' must be run from the command-line.
# this rule removes all .class files, so that the next make rebuilds them from scratch
# note that our code has not defined the RM variable, since Make already includes it in its pre-defined variable set, although you could define the variable manually if desired
clean:
        $(RM) *.class