Ant versus Maven

There are many ways to organise build systems for Java projects. The two most predominant are probably still Ant and Maven.  Debates between the two tend to go around in circles with the balance now swinging towards maven - since IDE support has got better (particularly Eclipse).  My own view is if you do not have a good architecture which is modular in nature and which separates concerns that should be separated you'll run into trouble no matter what you use.  The emphasis should always be on good architecture first and foremost.   

That said, I made this short video which illustrates some of the arguments you hear from Maven-ites and Ant-ists.  It is a debate between Maeve and Anthony.  Maeve is arguing for Maven; Anthony is arguing for Ant. Obviously, it's impossible to cover every single argument but the video includes some of the principle ones. Get some popcorn and enjoy.

Problems debugging Java after ANT compile

ANT    

Ok, this one is pretty easy but worth posting. I lost a few hours because of it and I don't want the same to happen to you! Suppose you want to be able to pass a switch into an ANT target which performs a javac to tell it to include debug information or not.

Your properties file will contain properties such as:
The ANT compile target then uses these properties:

However, the debug information is not there when you are debugging.  You run
ant -v compile to get more information. You see:

Now, as we can see the properties are echo'd as expected.  But, the "-g:none" indicates the compile won't include debug information.  Before you tear your hair out, relax! You have just made a very silly mistake we all make at sometime. When ANT reads property files it reads all property values literally. This means there is a difference between "true" and "true ", i.e. boolean properties should not have trailing spaces otherwise they will not be read as boolean properties. This is what happened here.  Ouch!

Ouch - trailing space!

As it states in http://ant.apache.org/manual/Tasks/property.html, regarding property files: "Trailing spaces are not stripped. It may have been what you wanted."

So rip that trailing space and re-run the ant compile target.

You should see:


which means the compiler is going to add lines, vars and source debug information.  Happy debugging!


References:
1. http://ant.apache.org/manual/Tasks/property.html

Are you still fond of your ANT?

Ok you haven't caught the Maven bug and you're still using ANT. Here's two very simple Ant tips for you...

Tip 1: echoproperties

You're trying to debug things, you'd like to know details of the Ant and the JVM you're using. You'd also like to know details of the properties you have defined. You want this all quickly. Well look no further than Ant's built in target: echoproperties.

Wrap this around your own target so you can call it from the command line and that's it. I usually wrap it around a target called debug.

So I'd have something like this:


A sample output would be:




Tip 2: Those friggin' classpaths.

You're not a java developer unless you've spent some hours in your life banging your head of the wall because your classpath was incorrect. This isn't just a beginner's problem; it can even catch season pro's out. Especially when a class or set of classes is available from multiple jars. For example, you can easily use whatever
StAX implementation you want but if you forget to put the one you want on your classpath, your runtime will use the reference implementation from the JDK. So double check your classpath before you go around boasting of the performance improvements you're getting with Woodstox!

Right, so you want a target that will echo your classpaths so you can see them how ANT sees them. Well, in ANT you can't just echo paths. But, you can make property representations of paths and then just echo them.

So let's say you set up your properties, directories and classpaths as something like


All you do is create a target, which defines properties that represent these paths and
then you echo these properties.


Sample output:


Notice the way I have defined the properties locally to the target. This is because they are only relevant to the target echo.classpath. There is no need to make the global. Always try to encapsulate - even in Ant.

References:

1. http://ant.apache.org/manual/Tasks/echoproperties.html