In this lab, you will practice using Git, which is currently the most widely used and arguably the best version control system.
In this course, we will mostly be using EGit, which is the Git client software built into Eclipse. This lab will familiarize you with using EGit.
Before you start
Be aware of the following fact:
As with most worthwhile skills, becoming proficient with Git takes some work. The best advice is to think carefully about what you're doing.
Another thing to keep in mind:
Like OO Analysis, Git proficiency is a software development super power.
Step 1: Create an ssh keypair
Execute the following commands in Cygwin terminal:
::
export HOME=/cygdrive/h
ls ~/.ssh
If this command shows the files id_rsa and id_rsa.pub, then you can continue to Step 2. Otherwise, execute the following commands:
::
ssh-keygen -t rsa -b 2048
When prompted for a passphrase, just press enter.
Step 2: Add your public key to your GitHub account
Log into GitHub. Click on the account settings icon in the top right of the page. (It looks like a wrench and a screwdriver.)
Click on the SSH keys item on the left side of the account settings page.
Click the Add SSH key button at the top right of the SSH Keys list.
Enter "YCP" as the title. In Notepad++, open the file H:/.ssh/id_rsa.pub. Copy the text in this file, and copy it into the Key textbox. Then press the Add key button. You might need to enter the password for your GitHub account.
Step 3: Fork
Log into GitHub using your GitHub account.
Go to the following GitHub repository page:
https://github.com/daveho/MoveTheSquare
Click the Fork button. This will make a clone of this repository in your own GitHub account. This will be your public repository for this lab.
The repository you just forked contains an Eclipse project called MoveTheSquare, a game engine that will be the basis for the next great indie game. You will just need to add some additional gameplay features!
Step 4: Configure Eclipse
Start Eclipse. Choose Window → Preferences → to open the preferences dialog.
Choose General → Network Connections → SSH2. Make sure that SSH2 home is set to H:/.ssh and also that Private keys is set to id_dsa,id_rsa.
Next, choose Team → Git → Configuration. Use Add Entry... to create the following configuration entries:
Setting Value user.email your email user.name your name core.autocrlf true core.fileMode false
Use appropriate values for your email and your name. If you would prefer not to reveal your real name and email address, that's fine.
Also note the following:
Step 5: Clone your fork of the repository
In Eclipse, choose the Git Repository Exploring perspective. Click the "Clone a Git Repository and add the clone to this view" button.
In the web page for the repository fork you created in Step 3, copy the SSH clone URL and paste it into the URI tab of the dialog. The click Next twice and then Finish.
Next, choose the Java perspective. Choose File → Import... → Git → Projects from Git → Local. Select the MoveTheSquare repository and click Next. Click Next two more times, then click Finish. You should now have a MoveTheSquare project in your Eclipse workspace that is connected to your public repository (the fork you created in Step 3).
Step 6: Make changes
You can run the program by right clicking on GameView and choosing Run As → Java Application.
Make some changes to the code:
- change the colors
- make the square bigger or smaller
- use a circle instead of a square
- make the square move faster
- prevent the square from moving outside the boundaries of the window
Step 7: Commit and push your changes
Once you have made a change, right-click on the Move The Square project and choose Team → Commit. Enter a log message describing your changes.
Next, right-click on Move The Square and choose Team → Push.
If the push succeeds, you should be able to refresh your GitHub repository web pages and see the commit you just made.
Step 8: Fetch and merge changes from other people
Refer to the Fetch/Merge document for instructions on how to set up remote tracking branches to track the changes made by other people.
Find someone in the class whose changes you want to fetch and merge.
Using the Eclipse Git Repository Exploring perspective, configure a remote for that person's public repository. Then return to the Java perspective and fetch changes from the remote. Finally, merge changes from the remote tracking branch containing the changes you fetched.
Merge conflicts
If a merge does not cause any conflicts — meaning that the changes you merged did not make edits to any parts of the code that you edited in your changes — the merge succeeds and the result of the merge is committed to your private repository.
If the merge does cause conflicts, Eclipse will notify you and place a red conflict icon on all directories and files where conflicts occurred. Eclipse will also add conflict markers in the source code to show you precisely where conflicts occurred, and to indicate what the conflicting text in each conflicting change was. You will need to edit the code to remove the conflict markers and resolve the markers.
Once you have resolved a conflict, right-click on the file and choose Team → Add to indicate that the contents of the file have been restored to a consistent state.
Once all conflicts are resolved, you can commit the result of the merge.
If you see a merge conflict where a conflict marker shows a conflict between two identical or nearly-identical versions of the entire file, it means that you or someone you fetched changes from did not set the core.autocrlf property to true. If that happens,
Pushing following a merge
Once a merge has been completed, you should to a push so that your public repository is updated with the results of the merge.
