Ruby from Java Programmer's perspective!

One liners:

-Created by Yukihiro “matz” Matsumoto [Japan] around late 90s.
-Scripting language ; hence interpreted
-Memory is managed for you via a garbage collector.
-Objects are strongly typed.
-There are public, private, and protected methods.
-There are embedded doc tools (Ruby’s is called RDoc).
The docs generated by rdoc look very similar to those generated by javadoc.
-You don’t need to compile your code. You just run it directly.
-There are different GUI toolkits. Ruby users can try WxRuby, FXRuby,Ruby-GNOME2, or the bundled-in Ruby Tk for example.
-You use the end keyword after defining things like classes, instead of having to put braces around blocks of code.
-You have require instead of import.
-All member variables are private. From the outside, you access everything via methods.
-Parentheses in method calls are usually optional and often omitted.
-Everything is an object, including numbers like 2 and 3.14159.
-There’s no static type checking.
-Variable names are just labels. They don’t have a type associated with them.
-There are no type declarations. You just assign to new variable names as-needed and they just “spring up” (i.e. a = [1,2,3] rather than int[] a = {1,2,3};).
-There’s no casting. Just call the methods. Your unit tests should tell you before you even run the code if you’re going to see an exception.
-It’s foo = Foo.new( "hi") instead of Foo foo = new Foo( "hi" ).
-The constructor is always named “initialize” instead of the name of the class.
-You have “mixin’s” instead of interfaces.
-YAML tends to be favored over XML.
-It’s nil instead of null. == and equals() are handled differently in Ruby. Use == when you want to test equivalence in Ruby (equals() is Java). Use equal?() when you want to know if two objects are the same (== in Java).

JRuby:
- Java implementation of Ruby
- Runs on JVM
http://jruby.codehaus.org/Getting+Started

Eclipse Plugin
- Ruby Development Tool - RDT
http://rubyeclipse.sourceforge.net/download.rdt.html
http://www.ibm.com/developerworks/opensource/library/os-rubyeclipse/


Web Development:
- Ruby on Rails is a framework facilitates web applications development using Ruby.

Who uses Ruby?
- Not for generic enterprise applications- so no bigges use this now!
- Startups/companies with specific system powerful requirements[search etc] can use this
-

Job Market/Opportunities
- Competes with php,python,perl market
- Currently certainly not a replacement for Java/.Net for web development

Refer:
http://www.ruby-lang.org