jMonkeyEngine SDK: Version Control

Whether you work in a development team or alone: File versioning is a handy method to keep your code consistent, compare files line-by-line, and even roll back unwanted changes. This documentation shows you how to make the most of the SDK’s integrated version control features for Subversion, Mercurial, and Git.

For every team member, the file versioning workflow is as follows:

  1. Once: Download a working copy of the project from the repository (“checkout”).

  2. Regularly: Upload your own changes to the repository (“commit”).

  3. Regularly: Download updates by others from the repository (“update”).

Since the jMonkeyEngine SDK is based on the NetBeans IDE and the NetBeans Platform, you can learn about certain jMonkeyEngine SDK features by reading the corresponding NetBeans IDE tutorials (in the “see also” links).

Version Control Systems

The jMonkeyEngine SDK supports various Version Control Systems such as Subversion, Mercurial, and Git. No matter which of them you use, they all share a common user interface.

You can use file versioning alone or in a team. The advantages are that you can keep track of changes (who did it, when, and why), you can compare versions line-by-line, you can revert changes to files and lines, merge multiple changes to one file, and you can even undelete files.

Creating a Repository (Upload)


  • You must have a project that you want to version.

  • You must have version control software installed (Subversion, Mercurial, or Git) and have initialized a repository.

    • Tip: For Subversion, for example, the init command looks like this example: svnadmin create /home/joe/jMonkeyProjects/MyGame

  • The computer where the repository is to be hosted must be available in your team’s network, or you will only be able to use your repo locally.

    • Tip: Hosts such as SourceForge, GoogleCode, offer free version control services for open-source projects.

Now you create a repository to store your project’s files.

  1. In the jMonkeyEngine SDK, RMB click the project in the “Projects” window and choose Versioning  Import Into Subversion Repository (or initialize Mercurial Project, etc, respectively).

    • Tip: If you haven’t evaluated yet which system to choose, start with Subversion for now.

  2. Go through the wizard and fill in the fields to set up the repository.

Checking Out a Repository (Download)

You and your team mates check out (download) the repository to their individual workstations.

  1. Go to the “Team” menu and choose Subversion  Checkout (or Git or Mercurial respectively)

  2. Fill in your repo data into the wizard and click Finish.

    • If you want to be able to submit changes, you must have a username and password to this repository. Otherwise leave these fields blank.

  3. The repository is downloaded and stored in the location you chose.

  4. Use the File  Open Project menu to open the checkout as project and start working.

    • If the checkout is not recognized you need to choose File  New Project from Existing Sources

Of course you can also check out existing repositories and access code from other open-source projects (e.g. SourceForge, GoogleCode,

Updating and Committing Changes (Send and Receive)

Receiving the latest changes from the team’s repository is referred to as updating. Sending your changes to the team’s repository is referred to as committing.

  1. Before making changes, RMB click the project and select Subversion  Update to make sure you have the latest revision.

    • Get in the habit of updating regularly, always before you edit a version controlled file. It will spare you much grief.

  2. After making changes to the project, make certain your change did not break anything.

    1. Update, build, run, test.

    2. Look at the red/green/blue marks in the editor to review what you have deleted/added/changed. Click the marks to review all differences in a file.

    3. Choose Subversion  Show Changes to see all files that were recently changed – by you and other team members.

    4. Update again in case your team mates made changes while you were reviewing.

  3. If there are no conflicts and you want to commit your changes, choose Subversion  Commit from the menu.

  4. Write a commit message describing what you changed.

    • Remember, you are writing a message to your future self. Never write redundant stuff like “I changed something”.

Comparing and Reverting Changes

  • If you and another committer edited the same line, there is a conflict, and the jMonkeyEngine SDK will show an error message.

    • RMB click a file Choose Subversion  Resolve Conflict

      1. Compare the conflicting versions. Press the buttons to accept or reject each change individually.

      2. After the resolver shows green, save the resolution.

      3. Build and test the resolution, update, and commit.

  • RMB click a file and choose Subversion  Search History.

    • You can inspect a file’s history and see who changed what, why, and when.

    • You can roll back a file to a historic version if necessary.

  • In general, you can choose Subversion  Diff for any file to see two versions of a file next to each other.

No Version Control? Local History!

If you do not use any version control, you can still track changes in projects to a certain degree.

  • RMB click a file or directory and choose Local History to show or revert changes, or undelete files.

  • You can also select any two files in the Project window and choose Tools  Diff to compare them.

  • Local History only works for files edited in jMonkeyEngine SDK Projects (It does not work for other files, e.g. in the Favorites window.)

See also: