[WICKET-1483] Unusual ClassCastException (SimpleAttributeModifier to IBehaviorListener) processing onError.

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.3.0-final, 1.3.1, 1.3.2
• Fix Version/s: 1.3.6, 1.4-RC2
• Component/s: wicket
• Environment: Microsoft Windows XP [Version 5.1.2600] (Server & Client)
• Assignee: Igor Vaynberg
• Reporter: Miguel Munoz
• Created: 05/Apr/08 01:14
• Updated: 01/Feb/09 00:22
• Resolved: 01/Feb/09 00:22

Description

Build the application from the four class files and one html file below. Run class Start as an application. Go to your browser, to this URL:

http://localhost:4280/behaviorbug/

Type some text into the text field. After six characters, it will throw a ClassCastException.

Source:

package com.bugs.behaviorBug;

import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.ajax.form.AjaxFormComponentUpdatingBehavior;
import org.apache.wicket.behavior.SimpleAttributeModifier;
import org.apache.wicket.markup.html.form.TextField;
import org.apache.wicket.model.IModel;

public class BehaviorBug extends TextField {

public BehaviorBug(String id, IModel model)

{ super( id, model ); init(); }

private int kc = 0;
private int cc = 0;
private final SimpleAttributeModifier blackBorder = new SimpleAttributeModifier(
"border-color", "black" );
private final SimpleAttributeModifier redBorder = new SimpleAttributeModifier(
"border-color", "red" );
private SimpleAttributeModifier currentBorder = null;

private void init() {
setBorder( this.blackBorder );
AjaxFormComponentUpdatingBehavior changeWarningBehavior = new AjaxFormComponentUpdatingBehavior(
"onchange" ) {

@Override
protected void onUpdate(AjaxRequestTarget target)

{ System.err.println( "WarningTextField onUpdate onChange " + BehaviorBug.this.cc++ ); reColor(); }

};

// I'm trying to do something tricky here. I want it to validate after every
// keystroke, so the user can get instant feedback on when the data is good.
AjaxFormComponentUpdatingBehavior keyUpWarningBehavior = new AjaxFormComponentUpdatingBehavior(
"onkeyup" ) {

@Override
protected void onUpdate(AjaxRequestTarget target)

{ System.err.println( "WarningTextField onUpdate onKeyUp " + BehaviorBug.this.kc++ ); reColor(); // Thread.dumpStack(); }

// The implementation of AjaxFormComponentUpdatingBehavior only calls
// onUpdate
// when the field is valid. Since it won't update when the field is
// invalid, I
// can't get my instant feedback unless I call onUpdate() when there's an
// error.
// Since I can't override onEvent() (It's final), I override onError to
// force
// an update even when the field is invalid. This should be safe, since
// onError()
// is only called on invalid data with a null exception, in which case it
// does
// nothing.
// This, however, seems to be what causes the bug. I have no idea why this
// would cause the bug.
@Override
protected void onError(AjaxRequestTarget target, RuntimeException e)

{ // Called on validation error with a null e. super.onError( target, e ); // Throws e, if it's not null. Does nothing // otherwise. onUpdate( target ); }

};
add( changeWarningBehavior );
add( keyUpWarningBehavior );
}

private void reColor() {
if ( isValid() )

{ setBorder( BehaviorBug.this.blackBorder ); }

else

{ setBorder( BehaviorBug.this.redBorder ); }

}

private void setBorder(SimpleAttributeModifier border) {
if ( this.currentBorder != null && this.currentBorder != border )

{ remove( this.currentBorder ); }

this.currentBorder = border;
add( this.currentBorder );
}
}

package com.bugs.behaviorBug;

import org.apache.wicket.Application;
import org.apache.wicket.Page;
import org.apache.wicket.Request;
import org.apache.wicket.Response;
import org.apache.wicket.Session;
import org.apache.wicket.protocol.http.WebApplication;
import org.apache.wicket.protocol.http.WebSession;

/**

• @author Miguel Muñoz
• @version $Id$

• */
  public class BehaviorBugApplication extends WebApplication {

/**

• Constructor
  */
  public BehaviorBugApplication() { // empty }
  
  @Override
  protected void init() { // empty }

@Override
public Class<? extends Page> getHomePage()

{ return Index.class; }

/*

• (non-Javadoc)
• @see org.apache.wicket.protocol.http.WebApplication#newSession(org.apache.wicket.Request,
• org.apache.wicket.Response)
  */
  @Override
  public Session newSession(Request request, Response response) { return new BugSession( this, request ); }

public class BugSession extends WebSession {
public BugSession(Application application, Request request)

{ super(request); setApplication( application ); }

}
}

package com.bugs.behaviorBug;

import org.apache.wicket.markup.html.WebPage;
import org.apache.wicket.markup.html.form.Form;
import org.apache.wicket.markup.html.form.TextField;
import org.apache.wicket.model.Model;
import org.apache.wicket.validation.IValidator;
import org.apache.wicket.validation.validator.StringValidator;

/**

• @author Miguel Muñoz
• @version $Id$

• */
  public class Index extends WebPage {

/**

• */
  public Index()

  { Form form = new Form("form"); TextField textField = new BehaviorBug("testfield", new Model()); IValidator lengthValidator = new StringValidator.MaximumLengthValidator(4); textField.add( lengthValidator ); form.add( textField ); add(form); }

}

package com.bugs.behaviorBug;

import org.mortbay.jetty.Connector;
import org.mortbay.jetty.Server;
import org.mortbay.jetty.nio.SelectChannelConnector;
import org.mortbay.jetty.webapp.WebAppContext;

/**

• @author Miguel Muñoz
• @version $Id$

• */
  public class Start {
  private static final int defaultPort = 4280;
  /**

• @param args
  */
  public static void main(String[] args) {
  int port = defaultPort;
  if (args.length != 0)
  Unknown macro: { try { port = Integer.valueOf( args[0] ); } catch ( NumberFormatException e ) { System.err.println("Unable to parse port parameter \"" + args[0] + "\" as an integer."); System.err.println("Using default value of x " + defaultPort); } }

  Server server = new Server();
  SelectChannelConnector connector = new SelectChannelConnector();
  connector.setPort( port );
  server.setConnectors( new Connector[]

  { connector }

  );

WebAppContext web = new WebAppContext();
// web.setContextPath( "/workspace/WicketTutorial" );
web.setContextPath( "/behaviorbug" );
System.out.println( "CP: " + web.getContextPath() );
web.setWar( "src/main/webapp" + port );
server.addHandler( web );

try

{ server.start(); // Who was the bozo who declared this to throw Exception? server.join(); }

catch ( Exception e )

{ e.printStackTrace(); System.exit( 1 ); }

}
}

<html>
<head>
<title>Behavior Bug</title>
<link href="style.css" rel="stylesheet" />
</head>
<body>
<div id="container">
<div id="header">Behavior Bug</div>
<div id="content">
Type some text into the field below. After six characters, you'll get a stack trace.
<form wicket:id="form">
<input type="text" wicket:id="testfield" name="txt" width="35" size="25" /><p>
submit: <input type="submit" value="That's all, Folks!"/></p>
</form>
End of form.
</div>
</div>
Test of Build Process.
</body>
</html>

Issue Links

• is duplicated by: WICKET-1872 Url for behaviour and isTemporary flag of behaviour.