The quick fix:
Going through the iBatis docs can sometimes be tedious.  Fortunately, the solution is simple.  If you open your xml file dealing with the object in question, and go to your resultMap element for the class, you’ll typically have a result element for each column you’re dealing with.  Add an attribute called nullValue with a value to give the object in question in case a NULL is present.  It’s that simple. 

Here’s an example…
You have a table called Employee with several columns and create a POJO like below to hold that data:

public class Employee {
    private int id;
    private String login;
    private String password;
    private int authorityType;
    private boolean passwordExpired;
 
    // ... constructors and setter/getter methods here...
}

Let’s say that authorityType and passwordExpired were NULL values in the database.  Adding the nullValue attribute to the xml file like so would solve your issue:

<resultMap id="EmployeeResult" class="Employee">
  <result property="id"              column="id"                               />
  <result property="login"           column="login"                            />
  <result property="password"        column="password"                         />
  <result property="authorityType"   column="authorityType"   nullValue="1"    />
  <result property="passwordExpired" column="passwordExpired" nullValue="false"/>
</resultMap>

Here’s the basic code used:

long startTime = System.currentTimeMillis();
for (int i = 0; i < names.length; i++) {
    NameData nd = names[i];
    grid.setText(i, 0, nd.getName());
    grid.setText(i, 1, Double.toString(nd.getD1()));
    grid.setText(i, 2, Double.toString(nd.getD2()));
    grid.setText(i, 3, Integer.toString(nd.getRank()));
}
gridLabel.setText("Grid: "+(System.currentTimeMillis()-startTime)+"ms");
 
startTime = System.currentTimeMillis();
for (int i = 0; i < names.length; i++) {
    NameData nd = names[i];
    flex.setText(i, 0, nd.getName());
    flex.setText(i, 1, Double.toString(nd.getD1()));
    flex.setText(i, 2, Double.toString(nd.getD2()));
    flex.setText(i, 3, Integer.toString(nd.getRank()));
}
flexLabel.setText("FlexTable: "+(System.currentTimeMillis()-startTime)+"ms");

I’m pulling from an array of 100 which holds some data that’s used to populate the cells.  The creation of the tables is done before hand, I’m not sure if this gives an unfair advantage to the Grid, but that’s the way I’m doing it.

Try the test app yourself here .

Results
What I’m finding is that the Grid does beat the FlexTable, but not by much with a small data set.  Larger sets seem to widen the gap.  My guess for this is that since FlexTable has the ability to add rows (Grid is sized from the start) that it works much like how other resizable constructs work such as Java’s ArrayList. My reasoning for this is that the first time the test is run the speed is very slow on the FlexTable (especially in IE).  Repeated test runs after the initial are faster and I think this is because the table was being sized the first time as rows were added, and didn’t need to be resized during the following tests.

The other thing I’m finding is that performace varies based on browser.  I’m seeing FF run reasonably well.  With IE the Grid runs about the same as FF but the FlexTable runs considerably slower.  I also tested Opera and was stunned as it blew both others out of the water. 

Here’s some of the tests run with two different machines (one linux and one Windows):

MS Windows Machine

Linux Machine

Anyway, enough with the blabbing.  I’ve put together a simple example to add a right click context menu and override the default browser context menu using GWT. 

In the box below you can try it out, right-click in there and you can demo it.

In case the iframe doesn’t show up in your browser you can see and try the example here.
Now here’s how it’s done.

I used a DeckPanel to switch between several panels. The popup context menu is used to choose.  To allow the DeckPanel to catch the right-click event (and you can also listen for double-clicks and several other things) I extended the DeckPanel.   For simplicity I added “Adv” (Advanced) in front of the several classes I’ve extended so this one will be AdvDeckPanel.  The first thing to do in the constructor is add sinkEvents(). Then we’ll override onBrowserEvent() in the class.  Here’s the code:

public AdvDeckPanel() {
  super();
  sinkEvents(Event.ONMOUSEUP | Event.ONDBLCLICK | Event.ONCONTEXTMENU);
}
 
public void onBrowserEvent(Event event) {
  GWT.log("onBrowserEvent", null);
  event.cancelBubble(true);//This will stop the event from being propagated
  event.preventDefault();
  switch (DOM.eventGetType(event)) {
    case Event.ONMOUSEUP:
      if (DOM.eventGetButton(event) == Event.BUTTON_LEFT) {
        GWT.log("Event.BUTTON_LEFT", null);
        listener.onClick(this, event);
      }
 
      if (DOM.eventGetButton(event) == Event.BUTTON_RIGHT) {
        GWT.log("Event.BUTTON_RIGHT", null);
        listener.onRightClick(this, event);
      }
      break;
    case Event.ONDBLCLICK:
      break;
 
    case Event.ONCONTEXTMENU:
      GWT.log("Event.ONCONTEXTMENU", null);
      break;
 
    default:
      break; // Do nothing
  }//end switch
}

Notice the two lines in onBrowserEvent():
event.cancelBubble(true);
event.preventDefault();

These are the two lines that tell the browser not to show it’s default context popup menu. Also note that overriding the default context menu doesn’t work in all browsers, I’m not sure if this is a bug in GWT. If you’re using firefox then you’ll have no problems, with IE you may need to add the following to your html:

<body oncontextmenu="return false;">

Other than that there’s just a switch statement that checks the event type, in this case we’re interested with ONMOUSEUP, and we’ll call the listener’s onClick() or onRightClick() based on the Event’s fields.

AdvDeckPanel also has a reference to AdvClickListener which looks like:

public interface AdvClickListener extends ClickListener {
  void onClick(Widget sender, Event event);
  void onRightClick(Widget sender, Event event);
}

This reference is basically the same as ClickListener, but has a separate method to handle the right-click.  I also pass the Event object so I can get the x and y from the click so the context menu shows up at that location instead of the top-left of the screen.

AdvDeckPanel implements AdvClickNotifier which does the same thing as GWT’s SourcesClickEvents interface, but handles the AdvClickListener instead.

public interface AdvClickNotifier {
  public void addClickListener(AdvClickListener listener);
  public void removeClickListener(AdvClickListener listener);
}

So, once you have your widget (in this case the AdvDeckPanel) and the listeners set up to handle the right-click, then we add in the code to build the popup menu and commands that go with it.  I put all of this in the EntryPoint.  I have three widgets (panels) and a Command for each like this:

private AdvDeckPanel deckPanel = new AdvDeckPanel();
final private PopupPanel popupPanel = new PopupPanel(true);
private VerticalPanel defaultPanel = new VerticalPanel();
private SimplePanel imagePanel = new SimplePanel();
private SimplePanel sponserPanel = new SimplePanel();
 
Command showAlertCommand = new Command() {
  public void execute() {
    deckPanel.showWidget(0);
    popupPanel.hide();
    Window.alert("Hope this example helps.");
  }
};
 
Command showImageCommand = new Command() {
  public void execute() {
    deckPanel.showWidget(1);
    popupPanel.hide();
  }
};
 
Command showSponserCommand = new Command() {
  public void execute() {
    deckPanel.showWidget(2);
    popupPanel.hide();
  }
};

A Command is called when the MenuItem is clicked.

Now the code to build the menu, link the commands, and handle the right-click:

private void createPopupMenu() {
  MenuBar popupMenuBar = new MenuBar(true);
  MenuItem alertItem = new MenuItem("Show alert", true, showAlertCommand);
  MenuItem imageItem = new MenuItem("Show Oliver ", true, showImageCommand);
  MenuItem sponserItem = new MenuItem("Show sponser ", true, showSponserCommand);
 
  popupPanel.setStyleName("popup");
  alertItem.addStyleName("popup-item");
  imageItem.addStyleName("popup-item");
  sponserItem.addStyleName("popup-item");
 
  popupMenuBar.addItem(alertItem);
  popupMenuBar.addItem(imageItem);
  popupMenuBar.addItem(sponserItem);
 
  popupMenuBar.setVisible(true);
  popupPanel.add(popupMenuBar);
}
 
public void onRightClick(Widget sender, Event event) {
  int x = DOM.eventGetClientX(event);
  int y = DOM.eventGetClientY(event);
  popupPanel.setPopupPosition(x, y);
  popupPanel.show();
}

Lastly, to make the menu actually look like a popup menu I modified the CSS like so:

.popup {
  background-color: gray;
  border-color: gray gray gray gray;
  border-width: 1px 3px 3px 1px;
  border-style: solid solid solid solid;
}
 
.popup-item {
  font-weight: normal;
  font-size: 80%;
}

What this does is makes it so the border isn’t the thick default GWT blue, and uses a thin border with the right and bottom borders a bit thicker.  This gives the popup that shadowed look.

A couple of books worth checking out are: GWT in Actionand GWT in Practice
Here’s the source and more links.

In case the iframe doesn’t show up in your browser you can see and try the example here.

First, let me explain how it’s all done.  Using a list of colors, in this case different shades of yellow, you add and remove styles (a color) of a widget.  The colors are stored in the CSS file.  The change is triggered by a timer.  The YellowFadeHandler class has an inner class called FadeObject which holds a color and a com.google.gwt.user.client.ui.UIObject. This UIObject is the super class of all major GWT widgets and has the methods:

addStyleName(java.lang.String style)
and
removeStyleName(java.lang.String style)

The FadeObject class

private class FadeObject {
	private UIObject uiObj = null;
	private int color = 0;
 
	public FadeObject(UIObject uiObj) {
		this.uiObj = uiObj;
		this.uiObj.addStyleName(yftStyles[color]);
	}
 
	public void nextColor() {
		if (color == transparent_color) return;
		uiObj.removeStyleName(yftStyles[color]);
		color++;
		uiObj.addStyleName(yftStyles[color]);
	}
	public int getColor() {
		return color;
	}
	public boolean isTransparent() {
		if (color == transparent_color) return true;
		return false;
	}
}// end class FadeObject

The YellowFadeHandler class

  private List<FadeObject> fadeObjectList = new LinkedList<FadeObject>();
 
  public YellowFadeHandler() {
    Timer t = new Timer() {
      public void run() {
        if (fadeObjectList.isEmpty()) return;
        for (Iterator<FadeObject> iter = fadeObjectList.iterator(); iter.hasNext(); ) {
          FadeObject fObj = iter.next();
          fObj.nextColor();
          if (fObj.isTransparent()) {
            //if it hits the transparent color then fading is done so remove it.
            iter.remove();
            GWT.log("fade object removed", null);
            continue;
          }
        }
      }
    };
    t.scheduleRepeating(120);
  }
 
  public void add(UIObject obj) {
    if (obj == null) return;
    FadeObject fo = new FadeObject(obj);
    fadeObjectList.add(0, fo);
    GWT.log("fade object added", null);
  }

My YellowFadeHandler class holds a List of these FadeObjects.  When the timer fires, it iterates through the list and changes (removes the old and adds the new) styles of the widgets.  When the style is changed to the last color in the chain (transparent), the widget is then removed from the list.  So to have a widget go through the yellow fade, all that needs to be done is call handler.add(widget);
Super simple. Here’s the source.
A couple of books worth checking out are: GWT in Actionand GWT in Practice

Assuming you already have Eclipse CDT, the first thing you need to do is create a new project.  After starting Eclipse, click on File->New->C Project and you’ll get a dialog box to choose the type of project (executable, static library, shared library, etc).  For this example, I’m choosing Executable and Hello World ANSI C Project.  Put in a name and click Finish.

Next you’ll see you have a new project in the left-side panel with a .c file containing a simple hello world program.

Now in my example I’ll add the line #include <avcodec.h> to set up my include.  If you need to add an include directory (where your header files are located) then in the Eclipse menu go to Project->Properties then open the C/C++ Build branch and click on Settings.  On the right side click on the Directories branch of GCC C Compiler.  You can then add directories to your include path.

In this same dialog you can click on Libraries in the GCC C Linker branch to add any libraries to the project for linking.  The library I’m adding is the libavcodec.so shared library.  To add this (notice in the screenshot) I only need to add avcodec, without the prefix lib and .so extension.  This might be new to Windows programmers.  Since you’re adding a library it’s assumed to have the lib and .so in the name.

Now let’s just add a couple of lines to the main() so we can test a compile with the libavcodec library.

#include <stdio.h>
#include <stdlib.h>
#include <avcodec.h>
int main(void) {
   avcodec_init();
   avcodec_register_all();
   return 1;
}

And then to run it, in the menu toolbar click on the run arrow and choose Run As->C/C++ Local Application.

Getting no errors means success.

I needed to use JSNI recently.  Since GWT doesn’t provide a way to bring the browser to the front or top like javascript does with it’s self.focus(); I was able to use JSNI to call that line of javascript.  Here’s a quick example:

public static native void bringToFront() /*-{
  self.focus();
}-*/;

Then all you need to do is call the bringToFront() method like you normally would.  Along with noticing in the native keyword, you’ll immediate see that the block looks commented out.  JSNI has two tokens to mark the beginning and end of your javascript the /*-{ marks the begin and }-*/ marks the end.  Everything in between those tokens are assumed to be javascript.

There are more examples on GWT JSNI site.

• gchart is 100% GWT (meaning it’s not a javascript wrapper)
• It runs on the client-side. Some other charting APIs actually build the chart on the server-side as an image and return the link for the image.  This can be an advantage for some situations, so you may need to think about if you want a client-side or server-side render.
• Open source under Apache License, Version 2.0
• Very simple to use.

I put together a very simple example, and it shows how quickly you can build a chart.  The example is a compound interest financial calculator shown below (go ahead and try it out).  It has a few fields to enter your initial amount, annual contributions, interest rate, number of compounds per year and the number of years.  After clicking on the calculate button it will show your future amount and chart it.

In case the iframe doesn’t show up in your browser you can see and try the charting example here.

The simplicity of this charting API is the fact that the charts are GWT widgets.  Here’s the code for my compounding interest chart:

public class AmountChart extends GChart {
	public AmountChart() {
		setChartSize(240, 200);
		setPadding("4px");
		getXAxis().setAxisLabel("Years");
		getYAxis().setAxisLabel("$");
	}
 
	public void addPoint(double x, double y) {
		GWT.log("point added ("+x+", "+y+")", null );
		getCurve().addPoint(x, y);
	}
}

Then all I did was add it to the DecoratedTabPanel, put in the event listeners, the formula (which I got from wiki) and done.
You can download the full source here, and the entire application is client side.

Updated 2008-01-28: I updated the iframe that the form is in to be more friendly with IE. Also made a change recommended by John Gunther to remedy a problem with IE. Compiled using gchart 2.4 and I updated the downloadable source.

There are four things we’ll need to accomplish:
1. Place the log4j.properties file
2. Write a servlet that will initialize the logger.
3. Modify the web.xml file.
4. Modify the GWT -shell and -compile scripts.

1. Place the log4j.properties file

Under <gwt-project>/tomcat/webapps/ROOT/WEB-INF/ create a “classes” dir.  The “classes” dir is where you put the log4j.properties file.  Here’s the log4j.properties file I’m using:
log4j.rootCategory=DEBUG, dest1, dest3

! Log to the console
log4j.appender.dest1=org.apache.log4j.ConsoleAppender
log4j.appender.dest1.layout=org.apache.log4j.PatternLayout
log4j.appender.dest1.layout.ConversionPattern=%-5p %d{HH:mm:ss.SSS} [%-15.15t] [%-25.25c{1}] %m%n

! LOG TO A FILE
log4j.appender.dest3=org.apache.log4j.RollingFileAppender
log4j.appender.dest3.layout=org.apache.log4j.PatternLayout
log4j.appender.dest3.layout.ConversionPattern=%-5p %d{EEE MMM dd HH:mm:ss.SSS zzz yyyy} [%-15.15t] [%-25.25c{1}] %m%n

! Specify the file name
log4j.appender.dest3.File=./logs/hosted-log4j.log

! Control the maximum log file size
log4j.appender.dest3.MaxFileSize=3000KB
log4j.appender.dest3.MaxBackupIndex=3

2. Write a servlet that will initialize the logger.

Next you’ll want to have a servlet that will load the properties file and init the logger. This file (Log4JInitServlet.java) will go in the <gwt-project>/src/ dir.

package com.nick.example.server;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;
/**
* Log4JInitServlet
*
* This class should get loaded first (based on the web.xml),
* so it can init the logger.
*
* @author Nick
*/
public class Log4JInitServlet extends HttpServlet {
  static final Logger logger = Logger.getLogger(Log4JInitServlet.class);
 
  public void init() throws ServletException {
    System.out.println("Log4JInitServlet init() starting.");
    String log4jfile = getInitParameter("log4j-properties");
    System.out.println("log4jfile: "+log4jfile);
    if (log4jfile != null) {
      String propertiesFilename = getServletContext().getRealPath(log4jfile);
      PropertyConfigurator.configure(propertiesFilename);
      logger.info("logger configured.");
    }else{
      System.out.println("Error setting up logger.");
    }
      System.out.println("Log4JInitServlet init() done.");
  }
}

This servlet should be loaded first, which can be accomplished by modifying the web.xml file.

3. Modify the web.xml file.

This file is located in <gwt-project>/tomcat/webapps/ROOT/WEB-INF/
My web.xml file looks like:

<?xml version="1.0" encoding="UTF-8"?>
<web-app>
  <servlet>
    <servlet-name>Log4JInitServlet</servlet-name>
    <servlet-class>com.nick.example.server.Log4JInitServlet</servlet-class>
    <init-param>
      <param-name>log4j-properties</param-name>
      <param-value>/WEB-INF/classes/log4j.properties</param-value>
     </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet>
    <servlet-name>shell</servlet-name>
    <servlet-class>com.google.gwt.dev.shell.GWTShellServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>shell</servlet-name>
    <url-pattern>/*</url-pattern>
  </servlet-mapping>
</web-app>

Notice the line <load-on-startup>1</load-on-startup>, which tells tomcat to load the Log4JInitServlet first.

4. Modify the GWT -shell and -compile scripts.

Modify your gwt –shell and –compile files to add the log4j jar into the class path. Here’s my <project>-shell.cmd file. Take note of the log4j jar that I added.

[Windows]
@java -Xmx256M -cp “%~dp0\src;%~dp0\bin;C:/lib/gwt-windows-1.5.3/gwt-user.jar;C:/lib/gwt-windows-1.5.3/gwt-dev-windows.jar;C:/lib/gwt-windows-1.5.3/log4j-1.2.12.jar” com.google.gwt.dev.GWTShell -out “%~dp0\www” %* com.nick.example.HostedLog4j/HostedLog4j.html

[linux]
#!/bin/sh
APPDIR=`dirname $0`;
java -Xmx256M -cp “$APPDIR/src:$APPDIR/bin:$HOME/projects/gwt-linux-1.5.3/gwt-user.jar:$HOME/projects/gwt-linux-1.5.3/gwt-dev-linux.jar:$HOME/projects/lib/log4j-1.2.15.jar” com.google.gwt.dev.GWTShell -out “$APPDIR/www” “$@” com.nick.example.HostedLog4j/HostedLog4j.html;

Make sure to change the <project>-compile.cmd in the same way.
You can then run your <gwt-project>-shell.cmd and the logger should work. It will create a log directory in under <gwt-project> and place your log file inside there.

The EchoServer will open a listen socket on port 4444.  Compile it, run it and then to test it you can open a command prompt and type telnet localhost 4444

import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
 
/**
 * @author NickC
 */
public class EchoServer {
   private static final int BUFFER_SIZE = 256; 
   private static int listenPort = 4444;
 
   public static void main(String[] args) throws Exception{
      ServerSocket serverSock = new ServerSocket(listenPort);
      System.out.println("listening on port "+listenPort);
      Socket sock = serverSock.accept();
      System.out.println("new connection " + sock);
 
      InputStream sockIn = sock.getInputStream();
      OutputStream sockOut = sock.getOutputStream();
      byte[] buffer = new byte[BUFFER_SIZE];
      while(true) {
         Thread.sleep(50);
         int count = 0;
         if ((count = sockIn.available()) > 0) {
            if (count >= buffer.length) {
               count = buffer.length;
            }
            count =  sockIn.read(buffer, 0, count);
            System.out.println("echoing "+count+" bytes");
            sockOut.write(buffer, 0, count);
            sockOut.flush();
         }
      }
   }
}

Source in a file: EchoServer.java