From: "Hans Jörg Hessmann" <hessmann@...>
Date: 2003-10-19T20:35:25+09:00
Subject: ANN: rjava

RJava enables you to use Java classes from ruby using ruby-like syntax. For 
example:

	require "java"
	include JAVA
	JVM.start_tcp().import("java.lang.System").out.println("Hello World!")

lets the Java Virutal Machine print “Hello World!” on its console. A little 
more complex example shows most abilities of the current implementation:

	require "java"
	include JAVA
	def create_pane
		pane = @jvm.new("javax.swing.JPanel", @jvm.new("java.awt.GridBagLayout"))
		gbc = @jvm.new("java.awt.GridBagConstraints")
		label = @jvm.new("javax.swing.JLabel", "Some Text")
		gbc.fill = gbc.jclass.BOTH
		pane.add(label, gbc)
		pane
	end

	@jvm = JVM.start_tcp
	jframe_class = @jvm.import("javax.swing.JFrame")
	jframe = jframe_class.new("Ruby-Swing-Sample")
	jframe.setSize(300, 200)
	jframe.setDefaultCloseOperation(jframe_class.DISPOSE_ON_CLOSE)
	jframe.setContentPane(create_pane)
	jframe.setVisible(true)

It opens a Swing frame with a label on it.

The current implementation is an early preview with several limitations:
- The only supported communication channel between Java and Ruby is TCP/IP. 
Other channels using a pipe or JNI are planned for future releases.
- The communication is one-way from Ruby to Java. The next major release will 
allow call-backs from Java to Ruby by implementing Java interfaces with ruby 
classes.
- The Java objects that were referenced by ruby are never collected by the 
Java garbage collector. This will be fixed in the next major release.
- Tests, samples and documentation have to be added.
- Performance has to be optimized

If you are interested, get it from:

http://www.spricom.com/rjava/

Hans Jörg Hessmann