Interactive Web Physics - Windows Eclipse Sourceforge CVS Development Setup HOWTO

Taylor Brockman <brockman at> - 2007-Jan-18, Revision 1

Welcome to Interactive Web Physics. IWP is Java software that facilitates the animation, design, and distribution of interactive Physics Animations, all without requiring programming.By expressing interest in developing this software, you are continuing a project that started in 1998 at the North Carolina School of Science and Mathematics under the guidance of Dr. Loren Winters.

This document walks a new developer through how to check out the source code from SourceForge and get the latest development version building under Eclipse for Windows. This is quite a feat, as IWP has been developed primarily under RedHat Linux for the past 8 years!

I tagged the CVS Tree with "tag_2007-Jan-17_EclipseWindowsHOWTO" during the writing of this document. I had to make some CVS acsii / binary tweaks and check in my eclipse .project file to get things to work out of the box from CVS. I have walked through each of these steps twice and captured screenshots along the way.

Table of Contents

Part 1 : Tools Installation

1.1) To get started, download:
JDK 6:

Eclipse SDK 3.2.1:
(Just get the base free version, not any of the fancy packages)

And for command line builds: (not covered here, but not required.)
Apache Ant:, get the .zip

1.2) Install JDK 6 in C:\Program Files\Java\jdk1.6.0\

1.3) Unzip eclipse into C:\Program Files\eclipse\

1.4) Unzip apache-ant into C:\Program Files\java\apache-ant-1.7.0\

1.5) I made a start menu shortcut to C:\Program Files\eclipse\eclipse.exe

1.6) In the Start Menu -> Control Panel -> System -> Advanced, Set some environment variables.

1.7) I set these environment variables.
JAVA_HOME=C:\Program Files\Java\jdk1.6.0
ANT_HOME=C:\Program Files\Java\apache-ant-1.7.0
PATH=....;C:\Program Files\Java\jdk1.6.0\bin;C:\Program Files\Java\apache-ant-1.7.0\bin
    Where ... is what PATH's previous value was set to. Adding two new paths onto the end.

1.8) Start up Eclipse via C:\Program Files\eclipse\eclipse.exe. Check version = 3.2.1. You may have to close the 'Welcome' or 'Tutorial' an

1.9) You can check the version of Eclipse by Menubar -> Help -> About Eclipse SDK

1.10) Start up Eclipse via C:\Program Files\eclipse\eclipse.exe. Check version = 3.2.1. You'll be asked to choose a workspace, I recommend the default setting which puts it in your Documents + Settings directory (aka Home). After that, you'll have to close the 'Welcome' panel.

1.11) Open MenuBar -> Window -> Preferences. Navigate Java -> Installed JREs and make sure that the jdk1.6.0 is the selected VM.

Part 2: Check out CVS Source Tree

2.1) Make sure that you have a Sourceforge account and are a member of the Interactive Web Physics development project in Sourceforge.
Sourceforge IWP Project Page:

2.2) In Eclipse: MenuBar -> File -> New -> Project. Choose Projects from CVS.

2.3) Enter the Information to check out a copy of the project from CVS:
    Repository Path: /cvsroot/iwp
    User: brockman
    Password: ********
    Connection type: extssh
    Yes: Use Default Port
    Yes: Save Password

2.4) For the module name, enter . (Period, which means all modules. I don't really use modules properly)

2.5) Check out the project into the workspace. I called it iwp-cvs for clarity.

2.6) I use default workspace location

2.7) Select Tag = HEAD. This is the latest and greatest experimental version of code where new features go. Tagging + Branching is a different topic. Version 2 of IWP has it's own tag. This is how I timetravel to fix bugs in the past - and thus make them vanish in the present!

2.8) When you hit Finish, it checks everything out via SSH (Port 22).

2.9) You should see the new 'iwp-cvs' project all checked out in your Package Explorer.

Part 3: Compile IWP + Eliminate Warnings

3.1) Because the source doesn't live off of the top of the checkout, you'll need to link the source in. The way the project is configured in Eclipse, there is a default linking, but it's set to a path on my Windows system. You'll need to customize it.
Right click the project name, and open properties.

3.2) Choose Java Build Path, Choose Source Tab. Click [Edit]

3.3) Change the "Linked Folder Location" to the /src/ directory in your workspace that you set when you initially started Eclipse. Usually, C:\Documents + Settings\Username\workspace\. This may cause the code to build clean, which is good.

3.4) Navigate the srclinked folder in the Package Explorer and find the file. Double click to open it in the code editor. Take note of the 285 errors in the Problems tab.

3.5) Let's get rid of the Errors. Right click the project again and go to Properties. Chose Java Compiler -> Errors and Warnings on the left. Turn on Enable Project Settings, and Roll down the Potential Programming Problems section. Change the Serializable class without serialVersionUID to 'Ignore'.

3.6) Pressing Apply or OK will cause the code to build clean again, which is good.

3.7) Back to the Project Properties dialog, this time choose Java Compiler on the left. Enable project settings and change the Compiler Compliance Level to 1.4. Pressing Apply or OK causes another build clean, which is good.

3.8) You shoudl see an Eclipse iwp-cvs display with No Errors and No Warnings.

Part 4: Run and Debug the IWP Animator

4.1) Find the srclinked -> edu.ncssm.iwp.bin.IWP_Animator class in the Package Explorer. This has the main() that is called in the iwpStudent.jar manifest, and is the starting point of Animator Application Execution. Right click on this application and choose 'Run as Application'.

4.2) The Animator Starts up on your screen. Try playing with time controls and closing the window.

4.3) You can alter the command line arguments, runtime directory, and all sorts of other neat things by MenuBar -> Run -> Run.... Also, a neat trick to re-run the last command is to use the Green Play button on the toolbar in the Main Java Perspective. Run lives two buttons to the right of the Print icon.

4.4) To run your application in Eclipse debug mode, right click on the blue + gray bar to the left side of the code and choose Toggle Breakpoint, just at the start of the main function. When a breakpoint is set a blue dot appears in that side bar.

4.5) Now, Package Explorer -> srclinked/edu.ncssm.iwp.bin.IWP_Animator -> Right Click -> Debug As -> Java Application. You'll be asked about switching to the Debug Perspective. This is good. You should now be in debug perspective, with execution paused at your first breakpoint.

4.6) I am not going to go into how to debug in this document. You are just going to have to play with it and have fun. To return to source code editing Perspective: MenuBar -> Open Window -> Open Perspective -> Java.

Part 5: Edit Files and Commit changes to CVS

5.1) For demonstrations, I like to edit BUILD.txt to make the changes really subtle and not affect functionality. Open BUILD.txt in the package explorer, add some text, and then Right Click iwp-cvs project -> Team -> Synchronize with Repository.

5.2) The frist time you enter the Synchronize Perpsective, this popups shows up. I remember and press [Yes].

5.3) The Synchronize Tab shows all the files you will be committing to the tree. I have 3 here - my expected BUILD.txt text change, which I 2-Pane diffed on the Right hand side. Also, I have two config adjustments, which is cool - these were my error changes. Hopefully these will have persisted for you and you will not have had to perform steps 3.5 - 3.7.

I am a big fan of code reviews before committing to the tree. Please take a moment to review your changes before committing to the tree. Oh, and never break the build - the HEAD version of CVS should always compile cleanly without any warnings!

5.4) Once you have code reviewed your changes (or even better, had a fellow developer code review them), Press the commit button at the Top Right of the Synchronize Tab. The Commit window opens. This is where you enter a commit comment.

It is always a good idea to list Bug Numbers, and as much detail as you can in CVS comments. Often times years go by and it's useful to go back and review in detail what has changed in a file.

5.5) Once you commit, the Synchronization menu will be empty. To change back to the Java perspective, use the Perspective control at the Top Right, or Menu Bar -> Window -> Open Perspective -> Java.

Now it's time to get back into the code and fix some more bugs! Thanks to the Eclipse, Java, and Sourceforge Teams for access to such great, free tools.