The Griffon Trove: checking EDT violations

Executing code in the proper thread is a must for every Swing application, problem is that it's so easy to break the rules. Griffon is aware of this and tries its best to help you deal with the complexity of running code in and out of the EDT.

Since version 1.0.0 of the Swing plugin you can instruct the running application to warn you when an EDT violation occurs. Take the following code for example

griffon-app/models/sample/SampleModel.groovy
package sample class SampleModel { @Bindable String text = 'Click me!' }griffon-app/views/sample/SampleView.groovy
package sample application(title: 'Sample', preferredSize: [200, 100], pack: true) { button(id: 'mybutton', text: bind{ model.text }, actionPerformed: controller.clickMe) }griffon-app/controllers/sample/SampleController.groovy
package sample class SampleController { def model def view def clickMe = { assert !isUIThread() model.text = 'Changed by Model' view.mybutton.text = 'Changed by View' } }Running this application with the EDT violation checker enabled throws some interesting results when the button is clicked.$ griffon -Dgriffon.swing.edt.violations.check=true run-app Welcome to Griffon 1.0.0 - http://griffon-framework.org/ Licensed under Apache Standard License 2.0 Griffon home is set to: /usr/local/griffon // snip snip Launching application ... 2012-06-18 11:22:45,036 [main] INFO griffon.addon.SwingGriffonAddon - EDT violations check enabled. 2012-06-18 11:22:45,039 [main] INFO griffon.swing.SwingApplication - Initializing all startup groups: [sample] 2012-06-18 11:22:48,138 [pool-2-thread-1] WARN org.jdesktop.swinghelper.debug.CheckThreadViolationRepaintManager - EDT violation detected javax.swing.JButton[mybutton,0,0,200x78,alignmentX=0.0,alignmentY=0.5,border=com.apple.laf.AquaButtonBorder$Dynamic@22c393a1,flags=288,maximumSize=,minimumSize=,preferredSize=,defaultIcon=,disabledIcon=,disabledSelectedIcon=,margin=javax.swing.plaf.InsetsUIResource[top=0,left=2,bottom=0,right=2],paintBorder=true,paintFocus=true,pressedIcon=,rolloverEnabled=false,rolloverIcon=,rolloverSelectedIcon=,selectedIcon=,text=Changed by View,defaultCapable=true] at sample.SampleController$_closure1_closure2.doCall(SampleController.groovy:10) at sample.SampleController$_closure1_closure2.doCall(SampleController.groovy) at org.codehaus.griffon.runtime.util.AbstractUIThreadHandler$1.run(AbstractUIThreadHandler.java:41)The controller performs 3 tasks

1. Check if the current thread is the EDT or not. By default all controller actions are executed outside the EDT so this check should succeed.
2. Change the value model.text which should trigger a change in the UI. Groovy bindings are aware that the change will be propagated to an UI component, sending the value in the correct thread.
3. Change the button's text directly. This change breaks the Swing rule which is why we get a logged exception.

Keep on Groovying!