Updates von Andreas Höhmann Kommentarverlauf ein-/ausschalten | Tastaturkürzel

  • Andreas Höhmann 10:38 am Thursday, 19. January 2012 Permalink |
    Tags: ,   

    Good to know this Hibernate Envers API changes 

    Today I tried to update the hibernate version for an internal customer project from 3.6.0.Final to 3.6.9.Final. In the project we are using Envers to track entity revisions. I already posted about that here.

    I noticed that some tests broken with the new version. These tests doing something like this: „create a bean, do changes X times, check available revisions and changed properties from rev A to B“.  In the new version I missed some changed properties.  I’m so happy that we have some tests for that aspect because without them I guess I had found these effects.

    I found  this entries in the Envers user forum:

    – Envers not auditing properties in super class
    – Envers modification in Hibernate 3.6.8 is causing problems

    Then I use the „try and fail“ principle to find the latest working version: ONLY 3.6.0.Final works 😀

    So there was an API change from 3.6.0.Final to 3.6.1.Final. Since 3.6.1.Final Envers doesn’t inspect parent class (es) per default to find out the audit able properties. But it’s easy to fix that:

    • put a @Audited to all the base classes
    • or use org.hibernate.envers.Audited.auditParents() (if you can’t change the base class)


  • Andreas Höhmann 9:43 am Thursday, 15. December 2011 Permalink |
    Tags: ,   

    Use maven profile to recompile vaadin widgetset 

    Today I will show you my maven profile to configure Vaadin widgetset recompilation.

    The Vaadin wiki shows the basics … but I want widgetset update only if its necessary … so I moved the gwt/vaadin plugins in a profile and add a activation per file for this profile:

         Updates Vaadin widgetset definitions based on project dependencies
         Remove widgetset directory to trigger recompile:
           rm -Rf src/main/webapp/VAADIN/widgetsets/
               <!-- if you don't specify any modules, the plugin will find them -->
               <!-- if you don't specify any modules, the plugin will find them -->
               -Xmx512M -Xss1024k


  • Andreas Höhmann 12:15 am Thursday, 17. November 2011 Permalink |
    Tags: guava, hierarchical, iterator   

    Hierarchical Iterator 

    import static com.google.common.collect.ImmutableList.of;
    import java.util.Iterator;
    import java.util.LinkedList;
    import com.google.common.collect.AbstractIterator;
    import com.google.common.collect.Lists;
     * This Iterator could be used for hierarchical data structure (e.g. Trees).
     * @author Andreas Höhmann
     * @param <T>
    public abstract class AbstractHierarchialIterator<T> extends AbstractIterator<T> {
       private final LinkedList<Iterable<T>> stack = Lists.newLinkedList();
       private Iterator<T> current;
       public AbstractHierarchialIterator(final T start) {
       private AbstractHierarchialIterator(final Iterable<T> start) {
          current = start.iterator();
        * An concrete hierarchical iterator has to implement a method to 
        * visit the children of an element.
        * @param currentElement
        * @return never <code>null</code>
       protected abstract Iterable<T> childrenOf(T currentElement);
       protected T computeNext() {
          while (true) {
             if (current.hasNext()) {
                final T next = current.next();
                return next;
             if (stack.isEmpty()) {
             current = stack.removeFirst().iterator();
          return endOfData();


    AbstractHierarchialIterator<Foobar> i = 
        new AbstractHierarchialIterator<Foobar>(foobarStart) {
        protected Iterable<Foobar> childrenOf(final Foobar currentElement) {
            // <--- here you have to implement something
            return currentElement.getFoobarChildren(); 
    // example 1 - show all foobars
    while (i.hasNext()) {
    // example 2 - search the first "foo"
    Foobar foo = com.google.common.collect.Iterators.find(i, new Predicate<Foobar>() {
          public boolean apply(final Foobar input) {
            return "foo".equals(input.getName());
        }, null);


    • bkiew 17:11 am Samstag, 19. November 2011 Permalink | Zum Antworten anmelden

      Some questions.
      a) The variable „stack“ is a LinkedList, why not a real „Stack“?
      b) In which order will the children be processed? In-, pre- or post-order? It is not configurable nor documented 😛

      Greetings, Ben

    • Andreas Höhmann 1:24 am Dienstag, 22. November 2011 Permalink | Zum Antworten anmelden

      Hi Ben,

      a) what class do you mean? Vector?
      b) this iterator will do it with http://en.wikipedia.org/wiki/Breadth-first_search, this simple code doesn’t need any documentation 😉 … you are right … a next step could be the usage of the strategy pattern, in combination with the builder pattern it would be quite easy to support all aspects of traversing a hierarchical data-structure.


      • xaerxess 20:23 am Montag, 20. August 2012 Permalink | Zum Antworten anmelden

        ad. a) ArrayDeque is superior to LinkedList (and Stack of course) if you use Java 6 and don’t need List interface goodies (positional get mainly). It even outperforms ArrayList; see this benchmark.

  • Andreas Höhmann 0:29 am Friday, 7. October 2011 Permalink |  

    RIP Steve Jobs 

    Steve Jobs 1955 – 2011

  • Andreas Höhmann 19:16 am Sunday, 18. September 2011 Permalink |  

    Gregor Gysi macht die Merkel zur Schnecke 


  • Andreas Höhmann 16:00 am Friday, 19. August 2011 Permalink |
    Tags: ffmpeg, gource, svn, visualization   

    Yet another gource svn video example 

    # makesvnvideo.sh
    svn log $1 --xml --verbose --quiet > svn-log.xml && \
    python $GOURCE_HOME/svn-gource.py --filter-dirs svn-log.xml > svn-gource-log.xml && \
    $GOURCE_HOME/gource.exe --log-format custom svn-gource-log.xml -c 2 -s 0.1 --max-files 500 --hide dirnames,filenames,files,mouse,progress --stop-at-end -i 60 --multi-sampling --user-image-dir ~/.avatars --camera-mode overview --font-size 18 --font-colour FFFFFF  --background 000000 --date-format "%d.%m.%Y" -r 25 -640x480 --highlight-users --user-friction .2 -o svn.ppm && \
    $FFMPEG_HOME/bin/ffmpeg.exe -y -b 10000K -r 25 -f image2pipe -vcodec ppm -i svn.ppm -vcodec libx264 -threads 4 -bf 0 svn.x264.mp4
    1. download/install gource, put a $GOURCE_HOME in your .bashrc
    2. download/install svn-gource.py into $GOURCE_HOME
    3. download/install ffmepg, put a $FFMPEG in your .bashrc
    4. put avatar images in your ~/.avatar directory
    5. put makesvnvideo.sh in your PATH

    makesvnvideo https://bloxel.googlecode.com/svn/trunk/

  • Andreas Höhmann 15:10 am Friday, 19. August 2011 Permalink |
    Tags: , label,   

    VAADIN Reverse Label with CSS 

    Here is a simple example how to use CSS to change the visual representation of Vaadin components.

    The com.vaadin.ui.Label component have a caption and a icon, i.e.  „[I] Caption“.

    But I need a label like this „Caption [I]“. This could be done with the following CSS:

    .v-caption-reverseLabel {
    float: left;
    .v-caption-reverseLabel .v-icon {
    float: right;
    margin: 0px 2px 0px 2px;
    .v-caption-reverseLabel .v-captiontext {
    float: right;
    final Label label = new Label();
    label.setIcon(new ThemeResource("img/info.gif"));
  • Andreas Höhmann 1:24 am Saturday, 13. August 2011 Permalink |
    Tags: , , perlin noise, tessellation   

    Bloxel Perlin Volume Renderer 

    We are making progress 😀

    I implemented a tessellation algorithm for volume -> mesh creation … here are some pictures from the bloxel labs …

  • Andreas Höhmann 10:04 am Saturday, 9. July 2011 Permalink |  

    Vaadin my first steps 

    A new customer project started this month. My team and I are creating a new web application. I’m the lead designer of the project and I think about new technologies for that application.

    After many projects with JSF and Richfaces I want to go new ways. First of all Richfaces is a great framework and you can do (almost) everything you want. But some requirements are very tricky to implement, i.e. confirmation dialog with user input, multiple windows …

    Currently I’m evaluating  Vaadin and I love it. It is so easy to use (at first sight). The java geek blog inspired me to try Vaadin.

    In the near future I will post more about my experiences. Stay tuned 🙂

  • Andreas Höhmann 10:41 am Friday, 8. April 2011 Permalink |
    Tags: Android, Megaminxer   

    Android Megaminxer 

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