Clipboard test snippet to get/set text data in JRuby and SWT.

clipboard.rb

require 'java'
require 'swt'

module Swt
  include_package 'org.eclipse.swt'
  include_package 'org.eclipse.swt.widgets'
  include_package 'org.eclipse.swt.dnd'
  import java.awt.datatransfer.StringSelection
  import java.awt.Toolkit
end

class Object
  include Swt
end

display = Swt::Display.new
shell = Swt::Shell.new display
shell.setSize 300+16, 300+38
cs = Swt::Composite.new shell, Swt::SWT::NONE
cs.setSize 300, 300

cb_get = Swt::Clipboard.new display
cb_set = Swt::Toolkit.getDefaultToolkit.getSystemClipboard
tt = Swt::TextTransfer.getInstance

b = Swt::Button.new cs, Swt::SWT::NULL
b.setText 'get'
b.setLocation 50, 50
b.pack
b.addSelectionListener do
  p cb_get.getContents(tt) # Works well!
end

b = Swt::Button.new cs, Swt::SWT::NULL
b.setText 'set'
b.setLocation 200, 50
b.pack
b.addSelectionListener do
  # cb.setContents(['hello hello hello'], tt) # NameError... why?
  cb_set.setContents Swt::StringSelection.new('hello hello hello'), self # Works well! Thanks, Roger!!
end

shell.open

while !shell.isDisposed do
  display.sleep unless display.readAndDispatch
end
display.dispose

Got a solution! Thanks to Roger!