Creating a project builder Ant buildfile
To see how project builders work, we will create a simple project
with a single source file and an Ant buildfile that jars up the single class file.
Though this example uses Java, it should be noted that project builders are
available for all projects, Java or otherwise.
- Create a Java project named 'HW'.
- Create a Java source file named 'HelloWorld' with a main method.
- Put a single 'System.out.println()' statement in the main method, and make
it print a greeting of your choice.
- Save changes.
- Create a file named 'projectBuilder.xml', open the Ant editor on it, enter
the following content, and save changes.
- In the Navigator, select the HW project and choose Properties from its
context menu.
- In the project properties dialog, select External Tools Builders, then
click New....
- In the 'Choose configuration type' dialog, make sure 'Ant build' is selected,
and click OK.
- The External Tools dialog appears.Set the name to 'Makejar'. In the Main
tab, use the first Browse Workspace... button to set the Location to be
the projectBuilder.xml buildfile created above. Then use the second Browse Workspace...
button to set the Base Directory to be the HW project.
- In the Refresh tab, we want to be sure that when our HelloWorld.jar is created,
we see it in Eclipse. By default, no refreshing is done when a project builder
finishes running, so check Refresh resource after running tool, then select
${project} in the list of scope variables. Because refreshing can be expensive,
you should in general refresh the smallest entity that contains all resources
that will be affected by your buildfile.
- In the Targets tab, the default target should be selected.
- In the Build Options tab, you can specify when this project builder is executed.
By default, this is set to full builds and incremental builds. Running your
project builder during auto builds is possible, though not recommended because
of performance concerns.
- Apply the changes and click OK.
- Back in the project properties dialog, you will now see a project builder
named 'Makejar' that is set to run after the default Java Builder. Note that
you can change the order so that your Ant buildfile runs before the Java builder,
though that wouldn't make sense in this example. Click OK to save the project
builder and close the dialog.
For a Java project, the default Java Builder will always be run and cannot
be removed. The Java Builder runs the internal Eclipse Java compiler which in
turn is responsible for indexing your source so that searching, refactoring and
many other features are available. Thus it is not possible to replace the internal
Eclipse Java compiler by using a project builder. Your only option with the
Java Builder is when it runs with respect to the project builders that you define.