------- PresentationModel.groovy ------------------
          
          import groovy.beans.Bindable
          
          public class PresentationModel{
          	@Bindable String name
          	@Bindable String firstName
          	@Bindable Date birthday
          }
          
          ---------- FormsTester.groovy ---------------
          
          import java.text.SimpleDateFormat
          import javax.swing.*
          import java.awt.Color
          import groovy.swing.SwingBuilder
          
          
          public class FormsTester {
          
          	public static void main(args) {
          
          		def dateConverter = { dateString ->
          			println "date converter: input=${dateString}"
          			new SimpleDateFormat("dd.MM.yyyy").parse(dateString)
          		}
          
          		def dateValidator = { dateString ->
          			println "date validator: input=${dateString}"
          			try {
          				def parser = new SimpleDateFormat("dd.MM.yyyy")
          				parser.lenient = false
          				parser.parse(dateString)
          			}
          			catch (Exception e) {
          				return false
          			}
          			return true
          		}
          
          		def model = new PresentationModel()
          
          		def swing = new SwingBuilder()
          		def frame = swing.frame(title: 'Forms Test', defaultCloseOperation:
          JFrame.DISPOSE_ON_CLOSE,
          				size: [800, 600], show: false, locationRelativeTo: null) {
          					panel {
          						tableLayout(cellpadding:10) {
          							tr {
          								td { label('Name:', id:'nameLabel') }
          								td {
          									textField(id:'nameText', columns:40,
          									text: bind(target:model, targetProperty:'name'))
          								}
          							}
          							tr {
          								td { label('First name:', id:'firstNameLabel') }
          								td {
          									textField(id:'firstNameText', columns:40,
          									text: bind(target:model, targetProperty:'firstName'))
          								}
          							}
          							tr {
          								td { label('born on:', id:'birthdayLabel') }
          								td {
          									/********* this code runs fine *****
          									def tf
          									def binding = bind (
          										validator: {  dateValidator(tf?.text)  },
          										converter: dateConverter,
          										target:model, targetProperty:'birthday'
          										)
          									tf = textField('01.01.1970', id:'birthdayText', columns:20, text:
          binding)
          									***********/
          
          									// this code crashes with an exception
          									def tf = textField('01.01.1970', id:'birthdayText', columns:20)
          									def binding = bind (
          										source: tf,
          										sourceProperty: 'text',
          										validator: {  dateValidator(tf?.text)  },
          										converter: dateConverter,
          										target:model,
          										targetProperty:'birthday'
          										)
          								}
          							}
          							tr {
          								td { label('reformatted:', id:'formattedBirthdayLabel') }
          								td {
          									def binding = bind (
          										converter: { it as String },
          										source:model, sourceProperty:'birthday'
          									)
          									label(id:'formattedBirthdayText', text: binding)
          								}
          							}
          						}
          					}
          				}
          		frame.show()
          	}
          }