Apache’s Maven is a great tool for managing a build environment: it keeps track of all project dependencies and provides a number of configurable build phases which can add depth to the build process. Building a project from the ground-up with Maven is a sure-fire way to keep it well organized and easy to maintain – but what about adding Maven on to an existing project, or worse, merging a non-Maven project into a project that already relies on Maven?

What follows is a look at some of the lessons I’ve learned from tweaking compiler plug-ins and digging through search results to debug various Maven-related issues. Hopefully it will be useful to the next developer who happens to hit similar issues, and if you have tips of your own be sure to leave a comment.

The maven-compiler-plugin <include> property

When overriding the default maven-compiler-plugin, the <include> tag may be used to force the compiler to include extra files into the build. There are a couple of interesting points to note here:

It is a filter. Many things in Maven expect a path to a directory, but not the <include> tag. If you have some extra java classes in src/main/java and you pass that to <include> it will fail silently – what you actually want is src/main/java/**/*.java.

It is for the compile-phase only. By default, in addition to using the maven-compiler-plugin during the compile phase, Maven will also use it during the test-compile phase. Most properties will apply to both, but <include> is not one of them; the test-compile phase requires a separate property, <testIncludes>, for any includables it requires[1].

The generate-sources and generate-resources phases

These phases are great for adding source (.java) and resource (.class) files to the compiler before the compile phase occurs. The snippet below shows how to use mojo's build-helper-plugin to add some obscure .class files to the classpath:

<plugin>
  <groupId>org.codehaus.mojo</groupId>
  <artifactId>build-helper-maven-plugin</artifactId>
  <executions>
      <execution>
          <phase>generate-resources</phase>
          <goals>
              <goal>add-resource</goal>
          </goals>
          <configuration>
              <resources>
                  <resource>
                      <directory>../obscure/classes</directory>
                  </resource>
          </configuration>
      </execution>
  </executions>
</plugin>

Now any .class files in ../obscure/classes (or any subdirectories) will be added to the classpath.

The same plug-in is used for adding .java files, simply tweak the generate-resources and add-resource values to generate-sources and add-source, and the <resources> and <resource> properties to <sources> and <source>.

The maven-compiler-plugin <compilerArgument> property

The <complierArgument> tag may be used to pass command-line arguments directly to the java compiler. Two examples:

<classpath> seems like it would let you add resources to the classpath, but near as I can tell, these aren’t actually used. Maven seems to prefer managing its own classpath, though we can still add/remove entries by overriding the default generate-resources phase (as explained above).

<sourcepath> is a great way to specify multiple source directories for compilation. It takes a semicolon-delimited list of top-level directories containing java files to compile. Alternately, an override of the generate-sources phase may be used here as well.

One gotcha with regards to sourcepath: to get this to work, I had to manually set <fork> to true on the maven-compiler-plugin. In fact, this gets even worse: when <fork> is true, Maven will use the %PATH% environment variable to determine which JRE to use, and this will fail with a totally non-descript error if the path to your JRE contains any spaces – very annoying to track down. This is actually a bug in Maven, logged here (http://jira.codehaus.org/browse/MCOMPILER-30).

The <sourceDirectory> property

A minor but important tag when playing around with various sources and resources, the <sourceDirectory> tag may be used to set the base directory for including java source files. It defaults to src/main/java, but I found when playing around with a lot of sources spread around various directories, it was easiest to set it to the current directory as follows:

<build>
  <sourceDirectory>.</sourceDirectory>
  {...}
</build>

Other useful debugging hints

When running into problems, it’s always good to have a few debug flags around to get a little more information out of Maven, which is generally not great at telling you what might be wrong.

Specifying the -e flag while running Maven will print out any exceptions Maven encounters, with the corresponding stack trace.

The <verbose> tag may be added inside any plug-in’s <configuration> property and when toggled to true (default is false) it will print some extra information, including the sourcepath and classpath being used by Maven’s compiler.

Specifying the -X flag while running Maven will document all kinds of intermediate steps Maven takes during the build – much more than -e and <verbose>.

Labels: compiler, Java, Maven

# posted by Dan M @ 10:44 AM 0 comments

LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 0, 
                new LocationListener() {
                    public void onLocationChanged(Location location) 
                    {
                        double lat = location.getLatitude();
                        double lng = location.getLongitude();                        

                        latitude.setText( Double.toString( lat ) );
                        longitude.setText( Double.toString( lng ) );
                    }

                    public void onProviderDisabled(String provider){}
                    public void onProviderEnabled(String provider){}
                    public void onStatusChanged(String provider, int status,Bundle extras){}
        });

Location location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);

final SmsManager sm = SmsManager.getDefault();
String phoneNumber = number.getText().toString();
String URL = "http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=";
URL += latitude.getText() + "," + longitude.getText(); 
sm.sendTextMessage(phoneNumber, null, URL, null, null);

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.SEND_SMS"/> 

Labels: Android, GPS, SMS

# posted by Sargsyan Tigran @ 9:08 AM 0 comments

public class TestClass
{
    public function generateEvent():void
    {
        var event:TestEvent= new TestEvent();
        event.type = TestEvent.TYPE;
        
        var dispatcher:Dispatcher = new Dispatcher();
        dispatcher.generator = TestEvent;
        dispatcher.dispatchEvent( event );
    }
}

public class TestClass
{
    public function generateEvent():void
    {
        var event:TestEvent= new TestEvent();
        event.type = TestEvent.TYPE;
        
        var handler:ResponseHandler = new ResponseHandler();
        handler.type = ResponseEvent.RESULT;
        handler.method = myCallback;
        
        var dispatcher:Dispatcher = new Dispatcher();
        dispatcher.generator = TestEvent;
        dispatcher.responseHandlers = [handler];
        dispatcher.dispatchEvent( event );
    }
    
    private function myCallback(event:ResponseEvent):void
    {
        trace( "callback reached!" );
    }
}

# posted by Dan M @ 10:14 AM 0 comments

How many people have experienced the modal pop up in desktop applications? They are commonly used across a wide variety of applications, one could say, too commonly used. While not appropriate for all situations, sometimes you need to use a pop up.

In XBAP applications the ability to open a pop-up is very limited; in many cases you will use navigation and multiple pages instead of separate windows. In most cases this is sufficient, but sometimes you really need to use a pop-up, and when you do a simple work around is to use the Popup control offered by WPF.

First, you define the Popup in the markup, making sure to set its StaysOpen property to true so it will remain open until you close it. (There’s no point in using the PopupAnimation or AllowsTransparency properties, because they won’t have any effect in a web page.) Include suitable buttons, such as OK and Cancel, and set the Placement property to Center so the popup will appear in the middle of the browser window.

Code sample:

<Popup Name="dialogPopUp" StaysOpen="True" Placement="Center" MaxWidth="200">

    <Border>

        <Border.Background>

            <LinearGradientBrush>

                <GradientStop Color="AliceBlue" Offset="1"></GradientStop>

                <GradientStop Color="LightBlue" Offset="0"></GradientStop>

            </LinearGradientBrush>

        </Border.Background>

        <StackPanel Margin="5" Background="White">

            <TextBlock Margin="10" TextWrapping="Wrap">Please enter your name.

            </TextBlock>

            <TextBox Name="txtName" Margin="10"></TextBox>

            <StackPanel Orientation="Horizontal" Margin="10">

                <Button Click="dialog_boxOK_Click" Padding="3" Margin="0,0,5,0">OK</Button>

                <Button Click="dialog_boxCancel_Click" Padding="3">Cancel</Button>

            </StackPanel>

        </StackPanel>

    </Border>

</Popup>

At the appropriate time (for example, when a button is clicked), disable the rest of your user interface and show the Popup. To disable your user interface, you can set the IsEnabled property of some top-level container, such as a StackPanel or a Grid, to false. (You can also set the Background property of the page to gray, which will draw the user’s attention to Popup.) To show the Popup, simply set its IsVisible property to true.

Here’s an event handler that shows the previously defined Popup:

private void popupTriggerButton_Click(object sender, RoutedEventArgs e)

{

    DisableMainPage();

}

private void DisableMainPage()

{

    mainPage.IsEnabled = false;

    this.Background = Brushes.LightGray;

    dialogPopUp.IsOpen = true;

}

When the user clicks the OK or Cancel button, close the Popup by setting its IsVisible property to false, and re-enable the rest of the user interface:

private void dialog_boxOK_Click(object sender, RoutedEventArgs e)

{

    // Copy name from the Popup into the main page.

    lblName.Content = "You entered: " + txtName.Text;

    EnableMainPage();

} 

private void dialog_boxCancel_Click(object sender, RoutedEventArgs e)

{

    EnableMainPage();

}

private void EnableMainPage()

{

    mainPage.IsEnabled = true;

    this.Background = null;

    dialogPopUp.IsOpen = false;

}

Using the Popup control to create this workaround has one significant limitation. To ensure that the Popup control can’t be used to spoof legitimate system dialog boxes, the Popup window is constrained to the size of the browser window. If you have a large Popup window and a small browser window, this could chop off some of your content. One solution is to wrap the full content of the Popup control in a ScrollViewer with the VerticalScrollBarVisibility property set to Auto.

If a Popup isn’t suitable for you, you can try another more “interesting” approach for showing a dialog box. Using the Windows Form library from .NET 2.0 you can safely create and host any WinForm control in your WPF application. In this case, you can create and show an instance of the System.Windows.Forms.Form class (or any custom form that derives from Form), because it doesn’t require unmanaged code permission. In fact, you can even show the form modelessly, so the page remains responsive. The only drawback is that a security balloon automatically appears superimposed over the form and remains until the user clicks the warning message. You’re also limited in what you can show in the form. Windows Forms controls are acceptable, but WPF content isn’t allowed.

Labels: .NET, c#, code sample, popup, WPF, XBAP

# posted by Romeo Dumitrescu @ 10:36 PM 0 comments

private var _rollOverTween:Object = {width:200, height:200, time:0.45, transition:"easeOutBack", onComplete:onRollOver};
private var _rollOutTween:Object = {width:90, height:90, time:0.2, transition:"linear", onComplete:onRollOut};

// An array which stores the UI components
// of our content
[ArrayElementType("CanvasBox")]
private var _content:Array;

private function closeOthers(event:MouseEvent):void
{
   for each(var component:CanvasBox in _content)
   {
      if(component != event.currentTarget)
      {
         component.roolOut();
      }
   }
}

# posted by Sargsyan Tigran @ 4:26 PM 1 comments

Labels: specification

# posted by Sylvain St-Germain @ 3:16 PM 0 comments

In some design scenarios launching multiple copies of the same WPF application is a problem, especially for document-based applications or server applications.

WPF does not provide a native solution for single instance applications; however there are several workarounds for this issue.

The most commonly used solution is to check whether another instance of the application is already running when the Application.Startup event fires. This is easily done using a system wide mutex (provided by the operating system to allow interprocess communication). While this is easily done, it limits the developer’s options by not providing a way for the new instance to communicate with the already running instance. Mainly this will provide only a simple way of limiting the number of running instances to one, while a separate system will be required to handle the new calls (usually through remoting or Windows Communication Foundation).

The recommended and more useful approach is to use the built-in support that’s provided in Windows Forms and originally intended for Visual Basic applications. This approach handles the messy plumbing behind the scenes. This means using an old style application class as wrapper for the WPF application. The wrapper will handle the instance management and will communicate the request to the already running instance of the WPF application.

Solution steps:

1) Add a reference to the Microsoft.VisualBasic.dll assembly.

2) Add a new custom class derived from the Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase class.

3) The IsSingleInstance must be set to true in the constructor. This enables a single instance application.

4) Override the OnStartup() method to create the WPF application object. (Note: The OnStartup() method is triggered when the application starts)

5) Overide the OnStartupNextInstance() method to handle future instances. (Note: The OnStartupNextInstance() method is triggered in when another instance of the application starts up)

6) Define a Main entry point for the application and create the wrapper object

7) Create the WPF application class

Sample of the application wrapper: 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using Microsoft.VisualBasic.ApplicationServices;

using System.Windows;

namespace SingleInstanceApplication

{

    //The Main entry point class

    public class Startup

    {

        [STAThread]

        public static void Main(string[] args)

        {

            SingleInstanceAppWrapper wrapper = new SingleInstanceAppWrapper();

            wrapper.Run(args);

        }

    }

    //The old-style application wrapper

    public class SingleInstanceAppWrapper : WindowsFormsApplicationBase

    {

        public SingleInstanceAppWrapper()

        {

            // Enable single-instance mode.

            this.IsSingleInstance = true;

        }

        // Create the WPF application class.

        private WPFApplication _app;

        //Override OnStartup() method to create the WPF application object

        protected override bool OnStartup(

             Microsoft.VisualBasic.ApplicationServices.StartupEventArgs e)

        {

            _app = new WPFApplication();

            _app.Run();

            return false;

        }

        // Override OnStartupNextInstance() to handle multiple application instances.

        protected override void OnStartupNextInstance(

             Microsoft.VisualBasic.ApplicationServices.StartupNextInstanceEventArgs e)

        {

            //In case of command line arguments, send them to the WPF application object    

            if (e.CommandLine.Count > 0)

            {

                _app.HandleCommandLine(e.CommandLine);

            }

        }

    }

}

As you can see, the sample above contains the Main entry point for the application. This is required because the wrapper must be created first.
If Visual Studio is used, by default the App.xaml application definition style is used. This will not work with the wrapper because the App.xaml approach already has a Main entry point.
Remove App.xaml and App.xaml.cs from the project and create a new class for the entry point.

The only thing left to do is to create the WPF application definition:

public class WPFApplication : System.Windows.Application

{

    //Override the OnStartup() method

    protected override void OnStartup(System.Windows.StartupEventArgs e)

    {

        base.OnStartup(e);

        //Load the main window

        Window _MainWindow = new Window();

        _MainWindow.Show();

        //Set the MainWindow property for the WPF application object

        this.MainWindow = _MainWindow;

    }

    //Method used to handle command line arguments

    public void HandleCommandLine (System.Collections.ObjectModel.ReadOnlyCollection<string> e)

    {

        //Code to handle command line arguments from other instances goes here

    }

}

Because the wrapper approach does not contain a XAML application definition (App.xaml), if you need to load application level resources, the following code can be placed the OnStartup() of the WPF application definition to load the resources from a resource dictionary:

        Application.Current.Resources.MergedDictionaries.Add(

            Application.LoadComponent(

                new Uri("AssemblyName;component/ApplicationResourceDictionary.xaml",

                UriKind.Relative)) as ResourceDictionary);

The above code will work for dynamic resource definitions. The static resource lookup process will fail because the source for the application resources dictionary need to be specified. In that case the code to load the resources will be replaced with the following:

Application.Current.Resources.Source = 

    new Uri("/AssemblyName;component/ApplicationResourceDictionary.xaml", UriKind.Relative);

Note: AssemblyName is a placeholder for the actual assembly name. The Uri for the resource dictionary location can be changed as required.

Labels: .NET, c#, embedded, Visual Basic, Win32, WPF

# posted by Romeo Dumitrescu @ 11:49 AM 0 comments