compile and run trivial Java with Rake

instant.rake

# instant.rake
# Rake rules for compiling and running trivial Java programs
# 
# Usage:  rake com.example.MonkeyShines
#  Source goes under ./src
#  Classes end up under ./target

require 'rake/clean'

libs = FileList["lib/*"]
libs << "target"
JavaClassPaths = libs.join(":")

# regex should weed out anything containing "/", i.e. paths
rule(/^[^\/]+\.\w/ => lambda {|tn| "src/#{tn.gsub(".", "/")}.class"} ) do |t|
  puts command = "java -classpath #{JavaClassPaths} #{t.name}"
  system(command)
end

rule ".class" => [".java", "target"] do |t|
  puts command = "javac -classpath #{JavaClassPaths} #{t.source} -d target"
  system(command)
end

desc "make directories, or whatever"
task :setup => ["src", "lib"]

directory "target"
directory "src"
directory "lib"

CLEAN.include("target")