Elias on Eclipse

EclipseCon Excercise update

Wed, 23 Mar 2011 18:20:41 +0000

Big thanks to all runners who keep showing up for the EclipseCon run each morning. Particularly the brave bunch running in the rain today!

Join us tomorrow at 7am in the Hyatt Lobby (rain or shine) for the last run of the conference.

We will also having a little contest with the chance to win Eclipse.org goodies: (thank you!)

two black Eclipse.org long-sleeve shirts
two women’s Eclipse.org polo shirts
Eclipse.org insulating coffee mugs — battle-tested in arctic Ottawa

Let’s run together at EclipseCon 2011

Sat, 12 Feb 2011 00:18:45 +0000

38 days left until EclipseCon — Sure, you’ve registered, booked the flight and hotel, checked your passport. Next: pack your running shoes!

Continuing the annual tradition started by Darin, we are organizing another edition of the EclipseCon Exercise: an easy 3-mile run, starting in the Hyatt Lobby at 7:00 am each morning, Monday to Thursday. The trail is flat and paved and follows the stream / bike path behind the Hyatt.

Some reasons to run with us:

have fun and enjoy the fabulous Californian weather
burn off last night’s food and beverages
network in an informal setting
get an EclipseCon 2011 runner’s shirt courtesy of EclipseSource

If you plan to join us, please RSVP on wiki.

Here’s a picture from last year’s group. I hope to have as many join in this year.

See you in Santa Clara,
Elias.

Portland DemoCamp 11/2010 – Photos and Slides

Sat, 13 Nov 2010 01:58:39 +0000

Thanks to everybody who attended or presented at the Portland Eclipse DemoCamp last Monday. This time the theme was “Eclipse for mobile developers”. We had about 50 attending, which is a strong uptick from past events.

Below some pictures and slides from the event:

1. Michael Galpin (@michaelg) from eBay opened the night with a presentation on ‘Android Development with Eclipse’. He introduced the Android platform and demoed the Eclipse-based Android Development Tools (ADT). Interesting fact: eBay’s mobile applications on Android are enjoyed by more than 3 million users. If you want to learn more about Android, Michael’s upcoming Android book should be a good place to start.

2. John Thomas from RIM continued with ‘BlackBerry Application Development Options‘. BlackBerry developers have a variety of language choices for developing apps, such as Java, HTML5/Javascript and Adobe AIR. All development tools are integrated nicely in Eclipse and Adobe’s FlashBuilder (also Eclipse based). Visit this page for details on BlackBerry app development.

3. Elias Volanakis (@evolanakis) talked about ‘iPad Development with Eclipse RAP‘. After introducing the project I demoed how to write a calculator web-app for the iPad using Java. We are optimizing RAP for mobile devices for the 1.4 release next summer. You can download the slides here.

Thanks for joining us,
Elias.

Portland DemoCamp: Mobile Development with Eclipse – 11/8, 6pm

Fri, 05 Nov 2010 21:39:37 +0000

If you want to learn more about Android / Blackberry / iPad development while enjoying some free pizza and beer, I would be glad to see you next Monday. Will have three presentations:

Android Development with Eclipse
BlackBerry Application Development Options
iPad development with Eclipse

The event is scheduled for this Monday, Nov 8th at 6pm at the Lucky Labrador Beer Hall, 1945 NW Quimby (map).

Please RSVP on the wiki (or sent me an email). Space is limited, so sign up now.

http://wiki.eclipse.org/Eclipse_DemoCamps_November_2010/Portland

Looking forward to see you there,
Elias.

Last week in Riena: 3.0 announced, Web support, ESE talks

Wed, 18 Aug 2010 23:02:07 +0000

Here are three recent developments from Eclipse Riena, that you may otherwise have missed:

• Version 3.0 announced – we have updated the development plan, skipping the 2.1 release and shooting straight for a 3.0 release next June (Eclipse Indigo). While we strive to keep the bulk of the APIs unchanged, this move will grant us the flexibility to carefully introduce changes needed to support Eclipse RAP.

You can read the full announcement here.

• Riena goes to the Web – We are excited about having all of Riena run on Eclipse RAP and are stepping up the effort.

In the last two weeks we have ported and committed the Riena Navigation to RAP. Thanks to recent improvements in RAP this was a breeze! We also have an automated build for this second platform. Lastly, we have worked to eliminate all compile errors when building against RAP. This should make further development more straightforward.

If you want to follow the effort add yourself on Bug 302893 and read the ‘Riena on RAP‘ page on the wiki.

• Riena at Eclipse Summit Europe - Riena committers are participating at the ESE, November 2 – 4 in Ludwigsburg. We have proposed following talks:

Riena on RAP (Running Riena in the Web)
Riena on e4 aka “RCP 2.0″
SWT on Qt
Tutorial: dynamic UI – from domain model to RCP app (Riena+Modelling+RedView)

If you are interested in any of these topics: please follow the link and leave a short comment. This will help the organizers decide which talks to approve. Thanks!

Eclipse RAP – What’s new in Helios? (Slides)

Wed, 18 Aug 2010 22:25:14 +0000

Here are the slides from my “Eclipse RAP – What’s new in Helios?“ talk, which I gave at the Bay Area Demo Camp in June. They capture the most interesting novelties of the RAP 1.3 release. You can find even more details in the full release notes.

I want to thank Oracle and AvantSoft for hosting and organizing the event.

If you are interested in future Eclipse events in the Bay Area, please take a moment to join the Bay Area Eclipse User Group on Meetup.com

Tip: How to detect that a View was Detached

Wed, 23 Jun 2010 20:15:49 +0000

Here is a question that I got on a post about detached views:

“How can I detect that a View has been detached from the main window? I would like to adjust the view’s behavior in that case.”

There is no API to obtain that information directly. However it is possible to do this with a few tricks:

detached views have an empty window title (i.e. shell.getText().length() == 0)
when a view is detached resize events are fired

Armed with that knowledge we can detect that a view is detached / reattached. The snippet below shows how (tested on windows).

PS: Our eclipse support helps developers use their time efficiently by providing prompt answers to questions like this one.

Ribbon IDE - EclipseCon Slides

Elias Volanakis — Mon, 22 Mar 2010 17:50:00 +0000

I've just uploaded the slides (pdf) from today's talk at EclipseCon. Thanks everybody who attended!

If you don't mind trying an alpha, you can download Eclipse 3.6 M6 with the ribbon here.

Error marker for SWT table rows – easy as pie

Thu, 04 Mar 2010 19:19:44 +0000

Here’s a nice addition to Riena’s TableRidget: you can now mark a table-row as incorrect.

This is done with an RowErrorMessageMarker. When hovering over the marked row, the corresponding error message will be shown in a tooltip.

IMarker marker = new RowErrorMessageMarker("An error message...", zorro);
tableRidget.addMarker(marker);
// to remove:
tableRidget.removeMarker(marker);

Full snippet here. This is shipping with the upcoming Riena 2.0 M6.

Shared libraries with Eclipse CDT and cygwin on Windows

Tue, 02 Mar 2010 23:55:07 +0000

“Can you help me use shared libraries with Eclipse CDT, managed make and cygwin?“, I was asked yesterday. Read on for a list of common pitfalls and detailed instructions.

The instructions are based on the latest CDT release (Galileo) and cygwin (make 3.81, gcc 3.4.4). They are applicable to CDT’s managed make projects (that means CDT generates a makefile to build project).

The Pitfalls

It turns out that using a shared library on Windows is not as straight forward as you think. There are several pitfalls waiting for the unaware to fall into:

1. Recent versions of cygwin’s make insist on cygwin-style paths instead of windows paths (/cygdrive/c/foo instead of c:\foo). CDT is not picky about this and will generate an incorrect makefile, if you use workspace relative paths:

make all
example.d:1: *** multiple target patterns.  Stop.

The solution is to use absolute cygwin paths, such as: /cygdrive/c/workspace/mymath

2. The compiler and linker will not find the header files / library unless you set the appropriate parameters. The compiler needs an include path (-I). The linker needs the library name (-l) and library search path (-L). These settings are scattered in two places in the project properties. Their location is not obvious for a first-time user (details below).

3. When launching, Windows will not find the shared library (.dll) and greet you with the error pictured below. Unix users might try to set the LD_LIBRARY_PATH, which has no effect on Windows. The solution is to append the directory containing the .dll to the PATH (MSDN Article). Restart Eclipse for the changed PATH to take effect.

The remainder of the post walks you through the process of creating and using a simple shared library with cygwin and CDT.

Creating a Shared Library with CDT

Follow these instructions to create a shared library project with CDT.

1. File > New > Project > C Project > Next. Project name: mymath. Ensure “use default location” is checked. Note the location: c:\workspace\mymath — we’ll need it later. Project type: Shared Library; Empty Project. Hit Finish.

2. Create a header file (mymath.h) and the corresponding implementation (mymath.c). The example below provides a trivial function that multiplies two integers:

3. Afterwards save and hit Ctrl+B (or Project > Build All) to build the library. If cygwin is on your path, you should see a “Release” folder in your project containing the file “mymath.dll”.

4. For windows to find the shared library, you need to add the directory containing the .dll to your path. On Vista this can be done via: Control Panel > User Accounts > User Accounts > Change my environment variables.

5. Exit and restart Eclipse after changing the PATH. Otherwise the changes will not be picked up.

Using a Shared Library with CDT

Follow these instructions to use a shared library in a “managed make” CDT project.

1. File > New > Project > C Project > Next. Project name: example. Project type: Executable; Empty Project. Hit Finish.

2. In that project create a file named example.c with the following content:

3. Save and hit Ctrl+B to build the project. The second line will have an error: “mymath.h: No such file or directory”. We now have to adjust the compiler and linker settings so that the mymath.h / mymath.dll files are found during the build.

4. Select the “example” folder in the Project Explorer. Select “Project > Properties” from the menu. A dialog comes up. In the tree on the left open: “C/C++ General > Paths and Symbols”. In the “Languages” list, pick “GNU C”. Then hit “Add”. Enter the cygwin-style path to the “mymath” project: /cygdrive/c/workspace/mymath

Caution: When entering the path, don’t use the “Workspace” or “File system” buttons because the resulting path will not be compatible with cygwin’s make.

5. In the same dialog select: C/C++ Build > Settings in the tree on the left. In the “Tool Settings” tab find: “Cygwin C Linker > Libraries”. Hit the “+” icon in the “Libraries” section and add the name of the library: mymath

Caution: if your shared library starts with lib, omit the ‘lib’ prefix (i.e. libfoo becomes foo)

Hit the “+” icon in the “Library search path” section and add the path to the folder containing the shared library: /cygdrive/c/workspace/mymath/Debug

Hit OK.

6. You will be asked to rebuild the project. Answer “Yes”, but for some reason this will not rebuild your project. Hit Ctrl+B to rebuild. The error will go away.

Note: ignore the “unresolved inclusion” warning. It seems that CDT has trouble resolving cygwin-style paths. The generated make-file however will work as expected.

7. Select “example” in the Project Explorer. Right-click > Run As > Local C/C++ Application. At this point you see the result of the multiplication on the console. That means that the shared library was found and used successfully:

Kind regards,
Elias.

Riena meets Eclipse RAP, goes to Browser

Sat, 20 Feb 2010 00:27:32 +0000

I’ve spend the last few days adjusting the Ridget layer in Riena, to make it work with Eclipse RAP and Eclipse RCP. We call this process “single-sourcing” (EclipseCon tutorial).

Ridgets wrap around standard SWT / RWT controls to provide additional functionality and a better API. One example that you can see below: Ridgets have “markers”, which tag a control as mandatory, wrong or read-only and change the control’s behavior accordingly.

It’s worth mentioning that all three screenshots run from the same code. The only difference is the target environment used (RAP or RCP).

Ridgets styled with RAP's "business" theme

Ridgets styled with RAP's "classic" theme

Ridgets in a regular RCP application

Once this work is completed the Ridget API will be usable for RAP applications as well.

To stay informed about this effort:

CC yourself to Bug 302893, and
come to our EclipseCon talk “Riena 2.0 - New & Noteworthy“

The Ribbon IDE - a leaner, modern UI for Eclipse

Elias Volanakis — Sat, 19 Dec 2009 07:00:00 +0000

Here's a short video about integrating the Hexapixel Ribbon widget into Eclipse. I'm working on this over the holidays. It will be available for free under EPL.

If you like this, please vote for my EclipseCon submission.

Don't see the video? Click here.

Eclipse Bug Patterns -- The selfish VerifyListener

Elias Volanakis — Fri, 17 Oct 2008 16:17:00 +0000

Here's a bug pattern I ran into the other day.

Let say we want to create a text field that accepts only digits:


 final Text text = new Text(shell, SWT.SINGLE | SWT.BORDER);

 VerifyListener onlyNumbers = new VerifyListener() {
   public void verifyText(VerifyEvent e) {
     e.doit = Character.isDigit(e.character);
   }
 };
 text.addVerifyListener(onlyNumbers);

A few weeks later the requirements change. We agree that the text field now accepts up to 10 digits. We add another VerifyListener as shown below.

Can you spot what's wrong with this code?


 final Text text = new Text(shell, SWT.SINGLE | SWT.BORDER);

 VerifyListener onlyNumbers = new VerifyListener() {
   public void verifyText(VerifyEvent e) {
     e.doit = Character.isDigit(e.character);
   }
 };
 text.addVerifyListener(onlyNumbers);

 VerifyListener maxLengthTen = new VerifyListener() {
   public void verifyText(VerifyEvent e) {
     String newText = getText(e);
     e.doit = newText.length() <= 10;
   }
};
text.addVerifyListener(maxLengthTen);

The problem

Both VerifyListeners are 'selfish'. They assume that each listener is the only one manipulating the e.doit flag (which has a true value by default). When e.doit is set to false, it blocks the modification of the text widget.

However, when there is more than one VerifyListener, e.doit might already be false. By ignoring this -- and setting e.doit back to true -- the listeners unintentionally permit operations which would otherwise have been blocked.

The solution

The solution is simple: always add a 'guard clause' to the top of the verifyText() method. It may seem unnecessary now, but you newer know if more VerifyListeners are going to be added to the widget at some point.


 final Text text = new Text(shell, SWT.SINGLE | SWT.BORDER);

 VerifyListener onlyNumbers = new VerifyListener() {
   public void verifyText(VerifyEvent e) {
     if (e.doit == false) {
       return;
     }
     e.doit = Character.isDigit(e.character);
   }
 };
 text.addVerifyListener(onlyNumbers);

 VerifyListener maxLengthTen = new VerifyListener() {
   public void verifyText(VerifyEvent e) {
     if (e.doit == false) {
       return;
     }
     String newText = getText(e);
     e.doit = newText.length() <= 10;
   }
};
text.addVerifyListener(maxLengthTen);

Happy hacking,

Elias

Showing different images for expanded / collapsed nodes of a JFace TreeViewer

Elias Volanakis — Tue, 22 Jul 2008 18:30:00 +0000

Did you ever want a JFace TreeViewer that shows different icons depending on the expanded / collapsed state of a node? The animation below shows what I mean:

Different images are shown in the tree, depending on the state of each node:

     — collapsed node
     — expanded node
     — leaf node

So here is what you need to do:

Create a LabelProvider that returns different images based on the expanded state of an element:

class NodeLabelProvider extends LabelProvider {   
  // ...
  public Image getImage(Object element) {
    Image result = LEAF;
    Node node = (Node) element;
    if (node.hasChildren()) {
      result = viewer.getExpandedState(node) ? NODE_EXPANDED : NODE_COLLAPSED;
    }
    return result;
  }
}

Create a TreeListener to update the image when the users clicks on the plus or minus icon in the tree:

class UpdateIconTreeListener implements TreeListener {

  public void treeCollapsed(TreeEvent e) {
    updateImage((TreeItem) e.item, true);
  }

  public void treeExpanded(TreeEvent e) {
    updateImage((TreeItem) e.item, false);
  }

  private void updateImage(TreeItem item, boolean isCollapsed) {
    Image image = isCollapsed ? NODE_COLLAPSED : NODE_EXPANDED;
    item.setImage(image);
  }

}

Tree elements can be expanded/collapsed via Java code by calling methods such as viewer.expandToLevel(Object, int) and viewer.collapseToLevel(Object, int). Remember to manually trigger an update of the element's label (i.e. the image and text) in those cases:
```
  viewer.expandToLevel(node, 1);
  viewer.update(node, null);
```

Download the example project.

Happy hacking,
Elias.

Riena Milestone 3 ships new UI for RCP applications

Elias Volanakis — Mon, 14 Jul 2008 20:01:00 +0000

The Eclipse Riena team quietly shipped M3 last week. This is a notable milestone for us because it is the first to include the "business-process oriented UI and navigation" that Riena is advocating as an alternative to the default workbench layout.

So what is Riena?

For a full description read the Riena proposal.

Some aspects of Riena that I find interesting: It tries to provide a simple UI-metaphor that caters more to the needs of business users. It tries to pave the road for UI-developers by providing high-level APIs for common UI programming tasks like using the data binding, rule-based validation and UI-markers (see screenshot).

To try it out, go to the Riena Getting Started page to grab Milestone 3. Note that M3 is still based on Eclipse 3.3. The screenshot above is from the "SWT Example Application" in org.eclipse.riena.example.client.

Progress is being made rapidly, so expect more interesting stuff to come in the next milestones.

Regards,
Elias.

Web-based IDEs? Less far-fetched than you think.

Elias Volanakis — Thu, 10 Apr 2008 20:42:00 +0000

Do you remember the Eclipse 4.0 "prototype" shown at the EclipseCon? Yes, the web-based Eclipse workbench? I must admit that I've not been very convinced that a web-based IDE would have much practical appeal. However seeing the demo videos for Heroku - a web-based IDE and hosting environment for Ruby on Rails applications - has changed my mind.

After all if the app has to be on the web and source == binary (Ruby is interpreted), why not put the IDE on the web too? Having the tools, the code and the runtime environment on-line makes several things easier:

Start working in a snap: Instant access to the source code from anywhere. No need to set-up an IDE. No need to set-up a local Ruby on Rails environment. No need to check out any code. Your data is there.
Instant collaboration: create a developer account. Send link to log-in page to developer. Start collaborating. (I hope it will support collaborative editing).
Deployment of the app is trivial. No need to find and configure a suitable server.
The "hosted-everything" aspect could make a great "source-forge-with-hosting" combo. Imagine finding a good web-application and just having to click on "deploy and run this on my account" for giving it a test drive.

This seems to be an excellent fit for Ruby and I'm looking forward to giving it a test-drive.

Now, how does it apply to Java web-apps?

Food-for-thought,
Elias.

Image Source: Heruko Demo Videos - (c) Copyright 2008 Heroku.com.

Getting Auto-Resizing TableColumns the Easy Way

Elias Volanakis — Mon, 05 Nov 2007 20:50:00 +0000

One of the less prominent novelties in Eclipse 3.3 is the new and shining TableColumnLayout, which re-adjusts the column widths in a table automatically when that table is resized. Previously this was only possible by installing a ControlListener and doing the required work yourself (*ouch*). Read on to learn how you can use it to save yourself some work.

Using the TableColumnLayout

// 1
Composite comp = new Composite(shell, SWT.NONE);
Table table = new Table(comp, SWT.BORDER SWT.V_SCROLL);
table.setHeaderVisible(true);
table.setLinesVisible(true);
// 2
TableColumn column1 = new TableColumn(table, SWT.NONE);
column1.setText("Column 1");
TableColumn column2 = new TableColumn(table, SWT.NONE);
column2.setText("Column 2");
// 3
TableColumnLayout layout = new TableColumnLayout();
comp.setLayout( layout );
// 4
layout.setColumnData( column1, new ColumnWeightData( 30 ) );
layout.setColumnData( column2, new ColumnWeightData( 60 ) );

One peculiar thing about the TableColumnLayout is that you do not apply it to the Table directly. Instead the Table has to be inside a composite that contains only the Table and nothing but the Table. See also Step 3.
We then proceed and create the TableColumns normally.
We create a TableColumnLayout and set it onto the containing Composite.
Using layout.setColumnData(...) we associate ColumnWeightData instances with each column in the Table. Those objects specify how the width is distributed amongst the columns in the table. The most common constructor is new ColumnWeightData( weight ), where weight is an integer that controls the relative width of the column (i.e. relativeWidth = weight / sum( weights of all columns ) ). By the way, you could also use ColumnPixelData to associate a fixed width with a column but since we want auto-resizing columns we'll skip that.

To see how much work we saved compare our snippet with an SWT-Snippet using a Control Listener to do the same job.

Known Limitations

Before you start using the TableColumnLayout you should also be aware of the following limitations:

the minimumWidth and (non)resizable settings of the ColumnWeightData are not supported properly
the layout stops resizing columns that have been resized manually by the user (this could be considered a feature though)

Snippets

Full TableColumnLayout Example (from above)
TableColumnLayout JFace Snippet
TreeColumnLayout JFace Snippet (this is the equivalent layout but for Trees)

Does your Eclipse 3.3.1 crash frequently? Here is help.

Elias Volanakis — Mon, 15 Oct 2007 11:14:00 +0000

Are you running Eclipse 3.3.1 on Windows using a Sun JVM? Does it crash frequently? Then you are probably affected by a combination of a low PermGen size on Sun VMs (64mb by default) and Bug #203325. Read on for instructions on how to mitigate this.

Update 7/19/2010: Eclipse (any version) and Java 6u21 has a similar problem causing frequent crashes. Be sure to change the eclipse.ini to use -XX:MaxPermSize=256m

Wait what is PermGen anyway?

PermGen stands for permanent generation and is the memory used to hold "data needed by the virtual machine to describe objects that do not have an equivalence at the Java language level. For example objects describing classes and methods are stored in the permanent generation" (related article). As it turns out the default size of 64m on Sun VMs is rather low for large apps like Eclipse. I tend to hit that barrier within 30 minutes. Normally the Eclipse command line arguments set the size to 256m, but Bug #203325 in Eclipse 3.3.1 prevents this. I was hit by this right after I upgraded to 3.3.1 this week. Fortunately, I was aware of the issue thanks to a discussion about OutOfMemory Errors at EclipseZone.

Here is what you can do:

Edit your eclipse.ini to replace the --launcher.XXMaxPermSize 256m entries with the a working equivalent. Remember: on Windows with Sun VMs only. If you are using larger software stacks (i.e. Webtools) you may even want to increase the size beyond 256m. The FAQ entry "How do I increase the PermGen size available to Eclipse" has the background information.

Modified eclipse.ini

Original eclipse.ini

-showsplash org.eclipse.platform
-vmargs
-XX:MaxPermSize=256m
-Xms40m
-Xmx256m

-showsplash org.eclipse.platform --launcher.XXMaxPermSize
256m
-vmargs
-Xms40m
-Xmx256m

Visit Bug #203325 to keep up with current developments. The issue has been fixed for the 3.3.2 service release, but there is a discussion going on about ways to make this fix available earlier.

Related Articles

Safety belt: How to save the Eclipse UI (workbench state) when YOU like

RAP Talk at the Portland Java User Group (Oct 16th)

Elias Volanakis — Mon, 08 Oct 2007 15:56:00 +0000

Are you curious about the Eclipse Rich Ajax Platform and based in Oregon / Washington? Then consider attending my talk "Java-based web-apps with the Eclipse Rich Ajax Platform" at the Portland Java User Group (free of charge, sponsored pizza).

During the talk I will:

introduce RAP to an audience of Java Developers (no Eclipse knowledge assumed)
explain key concepts
point-out noteworthy features
demonstrate the complete cycle of creating a small RAP application

The talk is scheduled for Tue, Oct 16th, at 6:30 PM at the Oracle Downtown Campus. Directions and more info...

See you there,
Elias.

How to save the Eclipse UI (workbench state) when YOU like

Elias Volanakis — Fri, 28 Sep 2007 03:09:00 +0000

At yesterday's Portland BarCamp Meetup, I was confronted with an interesting problem: David's Eclipse hangs / crashes frequently (probably that pesky PermGen issue) and when that happens the state of the Workbench is lost (i.e. which editors, views, windows are open) as it is only saved on shutdown. So we wrote a plug-in that periodically saves the UI state.

Download the plug-in here (source code here). Eclipse 3.3 only!

Here is what we did:

Since the UI state is saved when Eclipse shutdowns cleanly, we started by looking at the QuitAction. From here we went on to PlatformUI.getWorkbench().close(). A bit of exploration revealed that we need the methods in the snippet below.
```
// org.eclipse.ui.internal.Workbench
XMLMemento memento
  = XMLMemento.createWriteRoot( IWorkbenchConstants.TAG_WORKBENCH );
saveState( memento );
saveMementoToFile( memento )
```
As this code is internal, we copied it into an action which we added to the coolbar. Clicking on the "lock" icon will save the state of the workbench. BTW copying internal code can come back and bite you, but we ignored that in this case.
Then we made the plug-in save the UI state automatically. We added an IResourceChangeListener that is notified on POST_BUILD events. BTW this does not depend on the "auto-build" setting. Our listener will save the workbench state every 5 minutes. The help topic "Tracking Resource Changes" has more details. The listener is installed / removed in the plug-in activator:
```
public void start( BundleContext context ) throws Exception {
  super.start( context );
  // ...
  rcListener = new ResourceChangeListener();
  IWorkspace workspace = ResourcesPlugin.getWorkspace();
  workspace.addResourceChangeListener(
    rcListener,
    IResourceChangeEvent.POST_BUILD );
}
```
To make sure the plug-in is activated on start-up, we added a dummy contribution to the org.eclipse.ui.startup extension point.
If you want to monitor the plug-in's activities on the console, you can do that through a tracing option. Copy the following lines into a file called .options, place it in your eclipse directory and launch eclipse -debug
```
# file .options in eclipse directory
example.saveuistate/debug = true
```
After doing a build you should see some output like this:

Fri Sep 28 08:54:17 PDT 2007 Starting example.saveuistate
Fri Sep 28 08:54:30 PDT 2007 POST_BUILD resource change
Fri Sep 28 08:54:30 PDT 2007 Saving state.

6 Great Links for Eclipse Build Automation with PDE Build

Elias Volanakis — Mon, 24 Sep 2007 16:12:00 +0000

I was recently asked about some pointers for automated building of plug-ins and RCP applications with PDE Build. For most people the obvious starting point is the "Build and Test Automation" article on the Eclipse Corner, which was written in the Eclipse 3.0 time-frame and is now dated. Read on for pointers to more recent information.

By the way, PDE Build is a collection of ant scripts and plug-in code that helps people do automated headless builds from the command line. It is also used behind the scenes when exporting plug-ins and is part of the Eclipse SDK (org.eclipse.pde.build plug-in).

Great PDE Build Resources

For those that have a copy of the RCP book laying around, Chapter 24 - Building Hyperbola offers a good introduction and overview of PDE Build.
The Eclipse Help has a number of entries regarding automated building. These can be found under "Plug-in Development Environment Guide > Tasks". Building an RCP application from a product configuration file, Building Features and Advanced PDE Build topics are good starting points.
The slides from "PDE Build and build clinic" from EclipseCon 2007 have comprehensive coverage of most aspects of the PDE Build. After downloading the tutorial slides, unzip them and start with "PDE Build.ppt". Kudos to Andrew Niefer for making the slides available.

(As a side note, I would love to have the EclipseCon sessions available on DVD - like the DVDs from the JavaPolis conference. Every year I run across a few EclipseCon sessions I missed, which seem to be very useful for my current problem.)
The PDE Build Screencast by J Aaron Faar is based on Eclipse 3.2. It runs 18 minutes and has a good overview of the various files involved in the build. Skip the low-resolution Google Video version and download pdebuild.zip from the SourceForge project page instead. This archive contains a high-resolution quick-time screencast (pdebuild_screencast.mov) as well as the sample code.
The pluginbuilder is an Eclipse plug-in by Markus Barchfeld which comes with a form-based editor that makes dealing with the PDE Build configuration files really easy. The update site http://self.pluginbuilder.org/updateSite/ has an Eclipse 3.3 compatible version. You can also find a version for Eclipse 3.2 on the project's homepage.
After automating the build, the next step often is automating existing jUnit tests with the Eclipse Test Framework. The Eclipse Testing Instructions will help you get started. At the end of that document you will find an Ant template which you can use as a starting point. The Automated Testing Framework can be downloaded from the platform download page.

Know other good PDE-Build links? Then post a comment.

Hard hat image: (c) 2007, topfer/stock.xchng

See how you can make an RCP Application run in your browser

Elias Volanakis — Tue, 11 Sep 2007 15:29:00 +0000

Spurred by Chris Aniszczyk's recent blog post ("Web Development Revisited") I decided to post a RAP screencast showing how to convert the RCP Mail Template into a RAP application. The whole process takes just a few minutes. View screencast in new window.

Wait, what is RAP anyway?

RAP stands for Rich Ajax Platform. It is an Eclipse Project that enables Java developers to build browser-based AJAX applications using the full Java libraries, Eclipse APIs and a plug-in architecture. It does so by providing a web-enabled implementation of SWT, JFace and the Workbench.

Don't read about OSGi Best Practices, and you'll hate yourself later

Elias Volanakis — Thu, 19 Jul 2007 02:36:00 +0000

This presentation on OSGi Best Practices (pdf) was mentioned in the equinox newsgroup. It is a worthwhile read. Be sure to check it out.

I'm sure you'll be familiar with some of the pitfalls mentioned in the slides. Here are a few of those that I've come across:

Hide Implementation Details - Export internal implementation packages and somebody is bound to use them. Bad things will happen to them later, when this code is changed. As a result bad things may happen to you ;-).

With Eclipse: if you must export implementation packages (usually for tests) use the x-friends directive in your bundle manifest (as in: Export-Package: example.internal.impl;x-friends:="example.tests"). This will at least cause PDE to flag uses of that package in other bundles (but cannot prevent that usage).

Minimize Dependencies - Neglect this and you'll lose a lot of the modularity that comes from organizing your code into bundles.

Design your bundles thoughtfully. Manage their dependencies carefully. Know the differences between expressing dependencies through Import-Package or Require-Bundle statements and choose whatever is best for your case (read discussion).
Return Quickly from Framework Callbacks - This is especially important during bundle activation. Lazy initialization and threads help.

What has happened to me is, that start-up code which was initially quick became sluggish over time, as the initial assumptions changed. Having performance benchmarks in place can safeguard you from that. If you are willing to invest the effort to set-up and maintain such benchmarks, look at the org.eclipse.test.performance plug-in (overview, how-to).
Thread Safety - Framework methods of your bundle need to be thread-safe.

This bit me while I was trying to use a background thread to speed-up the start-up time of a bundle. That asynchronous code actually required another bundle to be active in order to run successfully, thus introducing a race condition. Installing an appropriate BundleListener solved this. I'll try to cover it in a future post.

Which of the problems from the slides did you run into?

Here is a Quick Way to Eliminate Dead Code

Elias Volanakis — Sat, 19 May 2007 08:04:00 +0000

If plug-ins were tools the Eclipse Core Tools plug-in would be a Swiss army knife. One of it's most useful tools is finding unused methods and fields in your code. I used it recently to remove obsolete code from my plug-ins.

To start removing unused code, follow these steps:

Download version 1.4.0 (for Eclipse 3.2) of the Eclipse Core Tools from this update site:
http://www.eclipse.org/eclipse/platform-core/updates/
In a workspace that contains all related code, select the project / package / file you want to work on.

(When I did this, I actually closed my unit-test projects because I didn't want to keep code around that is used nowhere but in tests. I refactored or removed the broken tests afterwards.)
In the context menu select Find Unreferenced Members. The results will be shown in the Search view.
Remove unreferenced code, but use your judgment!

Some code may appear unreferenced, that in fact isn't. Common examples:
- code that is contributed through extension-points
- code that is invoked through reflection
Some code may be unreferenced, but there might be good reasons for keeping it:
- unreferenced code that is API
- unreferenced fields in Serializable classes
- private constructors (if you use them to enforce non-instantiability or the singleton property - Effective Java, Items 2 and 3)
Repeat steps 2 - 4 as often as necessary.

What are your favorite tools for cleaning-up code?

Knife Image: (c) 2004, brokenarts/stock.xchng

Quick Access (Ctrl+3) is bliss!

Elias Volanakis — Sun, 06 May 2007 15:41:00 +0000

Are you one of those developers who try to get as much done as possible without lifting your fingers from the keyboard?

If you are, then you will love the new Quick Access (Ctrl+3) command introduced in Eclipse 3.3 M7. It allows you to access UI-elements - like Views, Perspectives, Commands, etc. - by just typing their name. And it supports Camel Case too.

Some usage examples:

Open the Navigator View? Ctrl+3, Navi, return
Debug Last Launched? Ctrl+3, DLL, return
Open the Debug Perspective? Ctrl+3, Perspectives D (Perspectives Debug), return
Return to the class WorkbenchAdvisor in an open editor? Ctrl+3, WorkbenchA, return (*)

The possibilities are endless...

Another subtle nicety is that Quick Access remembers the previously used choices, so the next time you press Ctrl+3 these are shown first.

(*) In the last example the file name is not matched when entering "WA". It seems that capital characters must be preceded by a whitespace in order to be picked up by the camel case matcher. E.g. "CC" would match Camel Case but not CamelCase.

Starting Eclipse 3.3 without the native launcher

Elias Volanakis — Mon, 30 Apr 2007 16:03:00 +0000

If you are working with Eclipse 3.3 M5 or newer you may have noticed that the file startup.jar is gone. In previous versions of Eclipse this file could be used to fire-up Eclipse directly and thus bypassing the native launcher (eclipse.exe):

java -jar startup.jar

In Eclipse 3.3 this functionality has been moved into the Equinox Launcher plug-in. As explained on the Equinox Launcher wiki page, it is still possible to start Eclipse using java by invoking:

java -jar plugins/org.eclipse.equinox.launcher_1.0.0.v20070319.jar

Note that the name of the jar-file is now version dependent causing naive scripts, that invoke the jar using the exact filename, to break once the jar-file gets updated. Instead you may want to look for a file matching org.eclipse.equinox_*.jar. Thankfully the Eclipse-wiki contains appropriate scripting templates that should give you a head start. If you want to avoid modifying existing scripts, you can also search for the Equinox Launcher plug-in, copy it into the Eclipse main directory and rename the copy into startup.jar.

How to validate plug-in dependencies in launch configurations with Eclipse 3.3

Elias Volanakis — Sun, 15 Apr 2007 13:49:00 +0000

I like to manage the list of plug-ins in any launch configuration manually so that new dependencies do not sneak-in unnoticed.

When doing this it is important to ensure that the dependencies of all selected plug-ins are satisfied. Otherwise some of those plug-ins will not work. To avoid this, you can click on the “Validate Plug-in Set” button to perform a dependency check. In Eclipse 3.2 this button is available on the “Plug-ins" tab of a launch configuration and is easy to spot.

In Eclipse 3.3 the "Validate Plug-in Set" button is harder to find, because it has been replaced by a toolbar item. To validate the plug-in dependencies you have to click on the check-mark icon as shown in the screenshot below.

Also, clicking on the black arrow next to the icon opens the pop-up menus shown below. It allows you to enable / disable the automatic dependency validation.

What Everybody Ought to Know About the Eclipse Help System

Elias Volanakis — Sun, 01 Apr 2007 16:14:00 +0000

The Eclipse Help System contains a wealth of useful information on both using Eclipse and developing Eclipse plug-ins. However making the most out it takes some time and experience. The tips below will get you up to speed by showing you how you can improve your searches, filter out unrelated information, discover related help topics and use on-line resources.

How to make the most of the Eclipse Help System

Are you a plug-in developer? Install the SDK download to get all the developer and ISV documentation.

The main Eclipse download page contains a number of different download archives. However only the Eclipse SDK archive will add the "Platform Plug-in Developer Guide" to the help contents. This guide contains a ton of information about developing plug-ins, using all kinds of APIs and the Extension Point and API reference. If you are a plug-in developer open the Help System (Help > Help Contents) and check that this guide is available.

If you are using additional Eclipse projects in your software - like GEF, EMF or Webtools - make sure you have installed their corresponding SDK features too.
Know the basic query syntax. By knowing a bit about the query syntax and the supported search operators you can make your searches more precise and effective.
- icon description - returns results containing both words (e.g. icon AND description)
- JDT OR icons - returns results containing any of those words
- "JDT icons" - returns results containing the exact phrase
- plugin NOT plugin.xml - returns results containing the word plugin and do NOT contain the word plugin.xml
- IDialog* - returns results containing any word starting with that term as in IDialog, IDialogSettings, IDialogConstants, etc.
You should also know that:
- search terms are case insensitive - searching for idialogsettings is as good as searching for IDialogSettings
- the search results will contain matches from the same word-root - searching for observing will return results containing observe, observer, observing, etc. This is done using a technique known as word stemming. Surround your term in quotes to perform an exact search (as in "observing").
- Read more about the query syntax.

Know how to configure the "Search Scope". This will let you specify which help guides are being searched. I often create a custom search scope named "devguides" that contains only the Developer Guides and the PDE Guide, effectively limiting the search results to information relevant to plug-in developers.

How to create a custom search scope

Click on the "Search Scope" link at the top of the help page.
Choose "New" in the Select Search Scope dialog.
Enter a name for your search scope (example: devguides) and check which the topics to search (example: Platform Plug-in Developer Guide, JDT Plug-in Developer Guide, Plug-in Development Environment Guide). Press "OK".
"devguides" should now be selected in the Select Search Scope dialog. Press "OK" close the dialog.

Congratulations! You created a custom search scope that contains all developer-related help topics. The active search scope is indicated at the top of the page.

To re-enable all topics choose "Search Scope > Search all topics".

Expose related information with the "Show in Table of Contents" action (). This will show you related information by expanding the path to the currently shown page in table of contents.
Bookmark interesting search results with the "Bookmark Document" action () to store them for later reading. You can list and manage your bookmarks in the "Bookmarks View" (). Bookmarks are persisted in your workspace and will be available any time your return to the Bookmarks View.
Access the Eclipse Help System on-line at http://help.eclipse.org/help32/index.jsp.

This has three benefits:
- All of the above tips apply to the on-line Help System too. Bookmarking (tip #5) is not possible, but you can use your browser's bookmarks instead. To bookmark a help page with Firefox click on the right frame and choose "This Frame > Bookmark This Frame..."
- The on-line Help System contains documentation for many Eclipse projects thus providing you with help for plug-ins that may not be available on your local installation.
- You can access the Help System anytime from anywhere in the world, even if you don't have an Eclipse installed (great when answering Eclipse-related questions from a random internet cafe).
Access older versions of the Help System online at http://www.eclipse.org/documentation/.

This is very handy when you want to find out if X was available in an older version of Eclipse. Currently you can access the help for these Eclipse versions: 3.2, 3.1.2, 2.1.3

What are your favorite help-related tips & techniques? Leave a comment below.

Get Custom-Colored Forms in 4 Easy Steps

Elias Volanakis — Sat, 24 Mar 2007 22:51:00 +0000

Find out how to use the Forms API to obtain custom colored form headings, as shown in the screenshot below. This might be especially interesting for RCP Applications that wish to distinguish themselves from the default Eclipse look and feel.

While reading about UI Forms enhancements in Eclipse 3.3 this paragraph captured my interest:

"We have elected to provide one combination of colors for title background rendering that will work well everywhere. The colors used to render the title are stored in the FormColors class under the following keys H_GRADIENT_START, H_GRADIENT_END, H_BOTTOM_KEYLINE1, H_BOTTOM_KEYLINE2"

Here is what those keys do:

H_GRADIENT_START - color to be used for the upper part of the heading
H_GRADIENT_END - color to be used for the lower part of the heading. A color gradient will be drawn if the two H_GRADIENT_... keys differ.
H_BOTTOM_KEYLINE1 - color to be used for the upper part of the separator line (which appears to be two pixel thick on my system)
H_BOTTOM_KEYLINE2 - color to be used for the lower part of the separator line

Here is how you can create a custom-colored form heading:

Create and configure a FormColors instance

FormColors result = new FormColors( display );
result.createColor( IFormColors.H_GRADIENT_START, red.getRGB() );
result.createColor( IFormColors.H_GRADIENT_END, darkred.getRGB() );
result.createColor( IFormColors.H_BOTTOM_KEYLINE1, darkred.getRGB() );
result.createColor( IFormColors.H_BOTTOM_KEYLINE2, black.getRGB() );
result.createColor( IFormColors.TITLE, white.getRGB() );
Create a FormToolkit with your form colors

FormToolkit toolkit = new FormToolkit( formColors );
Use the toolkit to create a Form

Form form = toolkit.createForm( parent );
Apply the colors to your Form heading

toolkit.decorateFormHeading( form );

Of course the above steps can also be used for ScrolledForm instances.

If you need more information, the example below contains the full source code. It contributes the view shown at the top of the post. After launching a run-time workbench with the example choose "Window > Show View > Other > Eclipse Nuggets > Form Colors Example".

Download Full Example (for Eclipse 3.3)

Have fun experimenting and be sure to avoid the two pitfalls mentioned below.

Pitfalls

Due to an implementation constraint you must always specify a value for the H_BOTTOM_KEYLINE_2 when using custom colors. If you don't your colors will be replaced by the default colors.
You must call toolkit.decorateFormHeading( form ) to apply your custom colors.

How to create GridData instances easily

Elias Volanakis — Fri, 16 Mar 2007 21:10:00 +0000

This post explains how to use the GridDataFactory (available since Eclipse 3.2) to avoid repetitive coding of similar GridData instances.

One of my favorite SWT layouts is the GridLayout. This layout will arrange widgets in a grid of rows and columns, as shown in the example above (three columns and four rows). When using the GridLayout three things tend to happen:

I need many GridData instances (one per widget).
A number of them will be configured in exactly the same way, since a group of widgets will have a similar placement. The first three Text widgets in the screenshot are such a case. This leads to code repetition or a number of similar helper methods.
A GridData instance is configured by setting the values of it's public fields. Configuring a single GridData instance will take a few lines of code. In my opinion, the resulting code bloat will make it harder harder to keep a "mental picture" of the UI in my head.

Here is how the GridDataFactory can help:

Method calls on the GridDataFactory can be chained, leading to more compact code

GridDataFactory.fillDefaults().grab( true, false ).span( 2, 1 );
A single GridDataFactory can create similar GridData instances

GridDataFactory gdf = GridDataFactory.fillDefaults().grab( true, false );
gdf.applyTo( txtName );
gdf.applyTo( txtOffice );
Two factory methods provide meaningful defaults: swtDefaults() and fillDefaults(). The second one is especially useful, since it creates a GridData instance that will cause the control to fill its cell

The snippets below illustrate the difference.

Before:

    Text txtName= createLabelAndText( group, "Name:" );
    GridData gridData = new GridData( SWT.FILL, SWT.DEFAULT, true, false );
    gridData.horizontalSpan = 2;
    gridData.widthHint = 200;
    txtName.setLayoutData( gridData );
    
    Text txtOffice= createLabelAndText( group, "Office Phone:" );
    gridData = new GridData( SWT.FILL, SWT.DEFAULT, true, false );
    gridData.horizontalSpan = 2;
    gridData.widthHint = 200;
    txtOffice.setLayoutData( gridData );

After:

    Text txtName= createLabelAndText( group, "Name:" );
    GridDataFactory txtGDF = GridDataFactory.fillDefaults().grab( true, false )
                                                           .span( 2, 1 ).hint( 200, SWT.DEFAULT );
    txtGDF.applyTo( txtName );
    
    Text txtOffice= createLabelAndText( group, "Office Phone:" );
    txtGDF.applyTo( txtOffice );

Download Full Example