These instructions outline steps how to develop CZT source code using Eclipse IDE. Information is based on Eclipse Mars (4.5).

Refer to general setup instructions for more details on CZT development setup.

We recommend using Eclipse m2e for building CZT using Eclipse and Maven. It is available as part of Eclipse RCP/RAP or Classic packages. Download one of these packages to use with CZT development.

Clone Git repository

Eclipse provides a Git client - EGit - as part of IDE. It can be used to clone CZT Git repository. If you have already checked out CZT source code, skip to the next step.

The general steps to clone a repository in Eclipse IDE are the following:

  1. Launch clone wizard by selecting Import > Projects from Git > URI
  2. In the repository information, supply the CZT repository URI: git://
  3. Select branches to clone (e.g. at least master - the main branch)
  4. Provide destination directory
  5. Select Import as general project to have the root directory visible as project in Eclipse
  6. Provide root project name, e.g. czt

This will create a new general project in Eclipse, which contains all CZT repository contents. For more information on using EGit, refer to its user guide.

Import projects into Eclipse

The Maven integration with Eclipse (m2e) project aims to provide first-class Apache Maven support in Eclipse IDE. However, it also aims to participate in Eclipse automatic builds, which causes problems with certain Maven plugins. See M2E wiki for more details on that.

If this is the first time you built CZT, you need to build it from the command line before importing into Eclipse. This is necessary because of CZT-specific Maven plugins, which are built on-the-fly. You can import them into Eclipse after everything is built first.

Furthermore, you need to install m2e connectors for CZT build before importing the projects (see below).

m2e connectors for CZT build

Several Maven plugins used by CZT require installing m2e connectors from 3rd party update sites (namely maven-jflex-plugin and xml-maven-plugin). They are not available in the official m2e marketplace and should be installed from the CZT developer Eclipse update site:

Install the connectors before importing CZT Maven projects:

  • m2e connector for maven-jflex-plugin, version >= 1.2.0
  • m2e Connector for XML Transform (xml-maven-plugin), version >= 3.0.0

Several other Maven plugins have m2e connectors available in m2e marketplace. Install them when asked during CZT project import.

Import CZT Maven projects into workspace

After installing all prerequisites and building everything from command line the first time, you can import the CZT projects into Eclipse IDE. To do that, follow these steps:

  1. (If EGit was used to checkout the source code, delete the czt project).
  2. Select File > Import > Existing Maven Projects
  3. Select root CZT directory and import all necessary projects
  4. If asked to get m2e connectors from the marketplace, allow that (restart Eclipse if needed)
  5. After import, wait until Building workspace job finishes (can take long!)
  6. Set CZT target platform (see below).
  7. If there are build errors, select all projects and refresh them. This should trigger another build.
  8. Done - this should get CZT projects built successfully.
  9. Launch CZT IDE from within Eclipse (see below)

Set CZT target platform

The target platform comprises all dependencies available for building CZT for Eclipse plug-ins. It is defined in project. Open the target definition file at / within Eclipse.

CZT target platform

When the target definition file is opened, wait for some time until its contents are resolved. Then select Set as Target Platform in the top-right of the editor. These dependencies will be loaded for use in builds and all CZT for Eclipse projects should build successfully now. Note that this needs to be done once at the beginning and then only if the dependencies/target platform change (close the target file afterwards to avoid unnecessary resolution).

If you still encounter build errors, try refreshing the projects (select all and choose File > Refresh) or cleaning them (Project > Clean).

Launch CZT IDE

For convenience, a launch configuration is provided to start CZT IDE from the checked-out projects. It defines all features and plug-ins that are required for CZT.

Select the launch configuration at /net.sourceforge.czt.eclipse.repository/czt-ide.launch. Choose Run As > czt-ide in the context menu.

CZT IDE launch file

This will launch CZT IDE as a separate application. All your changes will be reflected in the launched program. The launch configuration will also now be available in the main Run and Debug toolbars for convenient access. Use this launch configuration to run and debug CZT for Eclipse IDE.

Each imported project can now be linked to EGit to display changes and allow version control functionality on the source code. To link projects with EGit follow these steps:

  1. Select all of CZT projects
  2. Select Team > Share Project… from the context menu
  3. In the sharing wizard, select Git as the repository type
  4. Make sure Use or create repository in parent folder of project checkbox is selected. This relates the project to parent Git repository, as it is configured in CZT
  5. Select all projects to connect and click Finish.

Now EGit actions/decorations can be used on the projects.

CZT code style

CZT code style file is available for Eclipse IDE to provide common code formatting. Download it and import in Eclipse Preferences > Java > Code Style > Formatter tab.

Furthermore, you may want to use Eclipse Checkstyle plugin with CZT Checkstyle settings for additional code style checking.

Using Maven eclipse:eclipse

(This is an alternative way of using CZT in Eclipse and not needed if m2e is used.)

An alternative way of working with CZT in Eclipse is to convert the Maven plugins to separate Eclipse projects. For that we can use Apache Maven Eclipse plugin.

First of all, add Maven repository variable to workspace classpath. Eclipse projects will need to reference libraries in the local Maven repository. Add the M2_REPO classpath variable with the following Maven command:

mvn -Declipse.workspace=<path-to-eclipse-workspace> eclipse:add-maven-repo

Now Maven Eclipse can generate Eclipse projects with all dependencies for corresponding Maven modules. To achieve that, go to the root CZT directory (where the root pom.xml file is) and execute Maven command:

mvn eclipse:eclipse -DdownloadSources -DdownloadJavadocs

This will build CZT (can take a long time!) and generate Eclipse projects (i.e. .project and .classpath files) for each Maven module. Furthermore, it will attach sources and JavaDocs for referenced libraries.

Troubleshooting: out of memory

If the build fails with error java.lang.OutOfMemoryError : Java heap space, the available Maven heap space must be increased (see above).

Then rerun the initial command:

mvn clean
mvn eclipse:eclipse

Troubleshooting: ‘filtering’ is not identical

When building ui project, it can fail with the following error: Request to merge when 'filtering' is not identical. It seems to be an issue with Maven Eclipse plugin. A workaround is to use version 2.6 of the plugin. So resume the build with this plugin version:

mvn org.apache.maven.plugins:maven-eclipse-plugin:2.6:eclipse -DdownloadSources -DdownloadJavadocs -rf :ui

Import Eclipse projects into workspace

If the Eclipse projects were generated successfully with the step before, they can now be imported into workspace. Open Eclipse IDE and select File > Import > Existing Projects into Workspace. Browse to the root CZT directory and select to import all projects. Do not check “copy projects to workspace”.

This will import CZT modules as Eclipse projects and everything should build successfully. If some dependency errors exists, try building and installing CZT:

mvn clean install

Note that if source has been checked out using EGit into a root project, the root directory will only show the top project (already imported czt) in the Import wizard. In this case each project will have to be imported manually in the same way - just select each project in the Import wizard. Fix for this issue is underway in Eclipse.

If EGit was used to checkout the main CZT directory originally, you may want to close the root czt project, as its contents are now accessible via the subprojects.

Rebuilding after changes

The Eclipse projects are resolved with dependencies between projects, so when a file is changed, the affected projects are rebuilt. However, in some cases (e.g. when source code needs to be regenerated or if final JARs are needed), it is necessary to run Maven build again. In this case, run appropriate Maven commands from the the command line, e.g. mvn clean install.

It is possible to simplify this a little and define Maven as an external tool in Eclipse IDE. Then specific commands can be run based on the selection in Eclipse, e.g. select a project and then run clean install on the selection. For more information on configuring Maven as an external tool in Eclipse see the plugin usage documentation.

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Version: 1.6-SNAPSHOT. Last Published: 2016-04-09.

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