How to catch unhandled exceptions
2011-02-24
When you've got uncaught exceptions that terminate your application
you've got a bug. And a bug has to be fixed. Things change a little bit
when you have to maintain a five year old application and the
developers reveal more bugs than the tester. Especially when the bugs
terminate the application without a notice. Then you would like to have
a second line of defense that warns the user that something nasty has
happened.
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How to connect to an embedded derby via DataSource
2011-02-12
Here are some code samples on how to connect to an embedded derby
instance via DataSource.
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@Override and Interfaces in Java 6
2011-02-11
Today I've checked out a colleagues modules and got right away a
compile error. It was complaining that a method was not overriding a
method in any superclass. First I thought this error was caused due to
some changes in the library the class was based on. But the colleague
told me that he had checked in the latest version of the code and the
used libraries. While I was at his workplace to ask him some details
about his module he showed me the code in the IDE and there were no
error markers but it was the absolutely same code that I had.
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Refactor anonymous inner class to toplevel class in Eclipse
2011-01-14
When I need to provide Interface implementations or specialized classes
I often create anonymous inner classes. When the class stays small and
the isn't need at several places I keep the class where it is but when
not I want to move it to a top level class that has its own file. Of
course I can do copy&paste but with all the refactoring
possibilities that Eclipse offers this seems to be a little bit lame.
So I've searched a little bit and found a solution with Eclipse 3.6.1.
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Replace connection properties in persistence.xml with ant
2010-11-29
When developing a JPA based application you may want to have different
database settings for unit testing and production. The easy way is to
have two persistence.xml files and let the ant task select which one to
copy to your build artifacts. This approach gets very painful in the
long run. You always have to remember to make changes in both files.
And when you require a third connection you need to maintain three
files. Wouldn't it be better when there is one persistence.xml and the
different parts are in templates? Well I think so and the good news is
that you can do this completely with ant.
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Schemaexport with JPA 2.0
2010-11-12
Hibernates Schemaexport class is a great way to programmatically
populate a database with the current schema of your application. Of
course the class can't guess the database and other relevant options.
So a configuration is needed. With
org.hibernate.cfg.AnnotationConfiguration there is a class that
reads
in a hibernate.cfg.xml
and takes all needed properties from there. But
what to do when using JPA and there is only a persistence.xml?
AnnotationConfiguration won't take this xml file. Luckily
org.hibernate.ejb.Ejb3Configuration
will. See the following code:
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Run code without libs
2010-09-25
Run code without libs? What? Why? I had a utility class with references
to hibernate jars. This class should also be executed at the client who
doesn't have hibernate jars in its classpath. Why should it work? Well,
the utility class is determining the runtime environment. For that it
asks for the presence of "META-INF/persistence.xml". When there is
none, it assumes that it runs in the client. When there is one, it
checks the transaction type. Is it RESOURCE_LOCAL then it is executing
the local unit tests and when it is JTA it is executed on the
ApplicationServer. For checking the transaction type hibernate classes
are used.
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Exception when running wlappc from eclipse
2010-09-18
Recently I wanted to reorganize the jars imported from the weblogic to
our Java EE project. For this I've changed the path and the kind of
included jars. When I had found the minimal set of jars where the
compiler was running without errors I wanted to create a ear file.
Starting the build from eclipse I didn't get an ear file but the
following exception:
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Google App Innovator (beta)
2010-09-14
There are two magazines that I'm reading regularly: Javamagazin and c't. The first one focuses on
professional developers and project manager that are working on java
based projects while the second one targets advanced computer users.
Both have this month an article about Google App Innovator. A
tool were you should be able to create programs for the Android
platform via drag&drop of building blogs. These building blogs
remind of colored pieces of a puzzle. If you want to know more about it
you can read Googles
homepage. The interesting part about the articles is their
conclusion.
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Custom primary key generator and JPA
2010-09-10
As you may know from other posts I'm currently at the beginning of a
migration project from EJB 2.1 to EJB 3.0. So until recently we hadn't
much code to deploy. But as we had made some progress I wanted to
create a test deployment. Javac had compiled the code and some first
unit tests were all green. Everything OK? Wlappc didn't thought so.
Weblogics ejb compiler throw the following exception:
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