Can I work on just one or two modules from the NetBeans source base by themselves?

Apache NetBeans Wiki Index

Note: These pages are being reviewed.


Normally to work on modules versioned in the NetBeans main Mercurial repository you need to clone the entire repository. (For modules in contrib, you need contrib cloned as a subdirectory of main.) For people interested in just playing with patches to one or two modules this can be onerous, however. As an alternative, you can work on "orphan" modules from the source base ( has details). There are two issues to consider:

  1. Mercurial currently does not let you clone or check out just a subdirectory of a repository, so you will need to get module sources some other way (we are still considering some possibilities).

  2. Since "upstream" modules (that the module of interest depends on) are not available in source form, you need to have a recent development build of NetBeans available to compile against.

Quick usage guide

  1. Create an nb_all dir wherever you like. It must have at least the nbbuild dir from the source tree.

  2. Create nbbuild/ and in it set the property netbeans.dest.dir to the full path to a NetBeans IDE installation you would like to both compile against and build into (you should not use your real development IDE, rather a copy).

  3. Run: ant -f nbbuild/build.xml bootstrap

  4. Add subdirs for any module projects you would like to work on. (The modules may be already present in the target platform. If they are not, you need to check out sources for any transitive dependencies not in the target platform too.)

  5. Using the IDE, open the desired projects and work normally.

What works

Source projects should open without error and without displaying error badges, assuming all dependencies are available in either source or binary form.

You can build the projects normally. The modules will be built into the target platform (overwriting any existing copy of the module).

You can use Run and Debug to start the target platform with a test userdir after building the modules, set breakpoints etc.

You can Test the source projects normally.

Code completion should work against APIs present in other modules. If those modules are available in source form, you will get popup Javadoc automatically, and can navigate to sources. If not, you can still add popup Javadoc capability for all published APIs:

  1. Download "NetBeans API Documentation" from AU.

  2. Open NetBeans Platform Manager.

  3. Select the "default" platform and note the location of in the Javadoc tab.

  4. Create a new platform; select the same dir as you specified for netbeans.dest.dir.

  5. In the new platform, add to the Javadoc tab.


  • If you want to work on unit or functional tests, you need to have all test-to-test dependencies available as source projects, because we do not distribute test libraries. Sometimes the transitive dependency tree can get a bit big. For example, if the functional tests use org.netbeans.junit.ide.ProjectSupport, then you need to check out java.j2seproject (in whose unit test dir this class resides), then its dependencies in turn: projectapi, projectui, openide.filesystems, and openide.util. Test-to-module dependencies (e.g. nbjunit, jellytools, …​) can however be satisfied from the target platform’s binaries.

  • If you add new source modules to the tree, you will need to both restart NetBeans and delete the nbbuild/nbproject/private/ dir in order to reset all caches and ensure that the new sources are recognized.

  • Various targets in nbbuild/build.xml not used in the above scenarios may or may not work usefully, though this should not affect routine module development.

  • The target platform needs to be new enough to support any API calls you are making from source modules into binary modules. If the platform is older, you could see error badges. Besides getting a newer platform, this can be corrected by adding sources of the new version of the API module to the tree.

  • Note that the bootstrap ant target will not work if you just copy nbbuild from the source tree into nb_all. Other than nbbuild you also need to copy directories:

    1. ide/launcher

    2. javahelp

    3. apisupport.harness

Applies to: NetBeans 6.8 and above