In this project, you will learn to use some of the “team” features of your preferred IDE (Eclipse or NetBeans). We will use the “Git” source code control system to allow all members of the class to work on the same project at the same time, and then to merge in your changes. This is a “real-world” way of working on code; few developers work on real projects by themselves. (And even then, version control is often useful and used.)
The project is a very simple one.
Main.java has a
main method you need
Add a statement to
main to greet the class
by displaying a unique string (so your contribution differs from
other students'), which should include your name.
(You are free to add additional code if you desire!)
The purpose is simply to learn to use Git, which takes time and
lots of practice.
You can try using both IDEs, and make two changes if you want.
For this project, every student must individually commit their change(s)and submit this assignment. separately.
I have created a Git repository you can access from
This repository contains the initial version of
README.md file, and
The initial version has a greeting from the instructor you can use
as a model for your own addition.
Following the directions below, you will create a GitHub account
for yourself, and clone the current repo.
(IDEs generally require a local repo to work with.)
You use this repo just like any other Java project.
When you are done making a set of changes (for this project you only
need to add a single line to
main), you must
commit your changes.
That updates the local repository from your IDE's version.
Next, you Push your changes to the GitHub repo.
During this step you may discover another student has committed some
changes after you had checked out the project.
If so, you will need to merge your changes into the new version.
You can also update your local copy of the project, over-writing
your files with the latest ones from the repository.
You can perform other Git related operations with Eclipse or NetBeans. (Generally, I find the Git interface for NetBeans more intuitive than Eclipse.) It is expected that students will explore some of these operations. Eclipse assumes you may have multiple projects per repo, and thus creates a project top-level folder within the top (root) of the repo. NetBeans doesn't do that by default, but it is perfectly happy either way, so I set up the GitHub class repo using the Eclipse conventions.
Another issue is that Eclipse doesn't easily import non-Eclipse projects with existing sources. It can be done, but it was easier to create a default Eclipse project file and add it to the repo. It should be ignored by NetBeans, and it shouldn't be modifiable by Git; the repo was set to ignore changes to that file.
You can read about using these features with your IDE using the built in help system you have learned to use in a previous project. For more information visit the Git Home, especially the Git book online, and the other resources found on our class web page.
Creating a new Git repository is easy, on your own computer using either NetBeans or Eclipse, or at some code hosting site such as GitHub. Setting one up on your own server is harder. Linux CVS Repository Setup Directions is a transcript of the steps I used on YborStudent.
Using either Eclipse or NetBeans (you don't have to use both, although you can) complete the steps shown below for your IDE to setup a Git project. Then edit the shared Java program, test it, commit your change(s), and finally, push your changes back to the central repository (merging if necessary).
The first step is to make sure your IDE includes the latest Git plug-ins. These may have been installed already, or you may need to add one or more plug-ins for it. See your IDE's documentation to see how to add plug-ins. (You can add some others if you wish, but until you are comfortable with your basic IDE features, I suggest you resist the temptation to install much extra.) You should also check for updates, and install any found.
Next you need to create an account on GitHub.com. This is easy, fast, and free. When you have completed this step, you can create your own repositories there for practice. I strongly suggest you create one (or more), and practice using them with your preferred IDE before attempting any changes to the project's repo. (When done, you can delete any repo from its “Settings” screen.)
You must send an email containing your GitHub account name to your instructor. Only those listed as collaborators on Github.com can push changes to the COP-2805-2017 repo there, and I need to add your account name to the list. Once you are added by me, you will receive an email message from GitHub with an “invitation” to collaborate; you need to accept that before you are a collaborator.
There are Windows GUI and command line tools for working with Git and/or GitHub. They are not IDEs however; you view your repos, create new ones, and with some tools, add files or commit new versions of files. As the Git plug-ins for Eclipse and NetBeans includes a full version of Git, you don't need any other tool. (That is, this step is optional). Still, it is handy to be able to run various Git commands outside of an IDE, especially when trying to learn.
I would suggest installing either “Git for Windows” from git-scm.com, or “Cygwin” from cygwin.com if you run Windows 7 or older. Cygwin includes a full set of Linux tools, including (if you select it) Git. Git for Windows includes a sub-set of the command line Linux tools, just the ones you would need to work with Git. (It also includes a Git GUI, but it doesn't do much.) Windows 10 includes Ubuntu Linux, which includes Git. Git for Windows is probably your easiest choice.
user.name” with your full name, and “
user.email” with a working email address (such as your HCC Hawkmail address). This information will be automatically included with every commit.
If the email address you used is unknown to GitHub, your commits will not be linked to your GitHub account name! This is because GitHub accepts your commits if you know a username and password (or use an appropriate SSH key), but labels commit objects by your email address. You can list several email addresses in your GitHub account and then your commits will be recognized from any of them. Follow these directions to add additional email addresses to your GitHub account.
From Preferences→Team→Git, you can set a default location
for all your Git repos.
From Preferences→General→Workspace: Set the default text file encoding to UTF-8.
It's not required for our project, but the “Package Explorer”
hides many files by default.
In particular, it hides the “
To fix that, click on the tiny downward-pointing triangle on the right of
the Package Explorer tab bar, and click on “Filters...”.
Now un-check “
To re-hide the Eclipse project files, select “Name filter
patterns” at the top, and enter
.classpath, .project, .git, JRE*”
(without the quotes) in the box.
git”, not your Github name.
If all is well, you have cloned that repo locally. Next is to build a project from it. The Import... wizard should resume now.
Proj2” in our case).
Display README files in project view Git Toolbar
user.name” with your full name, and “
user.email” with a working email address (such as your HCC Hawkmail address). This information will be automatically included with every commit. The resulting
.gitconfigfile (in your HOME directory) should then look something like this (the file may have additional entries too):
[user] name = Hymie Piffl email = firstname.lastname@example.org
(Of course, you need to use your actual name and email address.)
If the email address you used is unknown to GitHub, your commits will not be linked to your GitHub account name! This is because GitHub accepts your commits if you know a username and password (or use an appropriate SSH key), but Git labels commit objects by your email address. You can list several email addresses in your GitHub account and then your commits will be recognized from any of them. Follow these directions to add additional email addresses to your GitHub account.
email@example.com:profwpollock/COP-2805-2017.git” should be changed to “
ssh://firstname.lastname@example.org/profwpollock/COP-2805-2017.git”. Next, browse to locate your private key file, created outside of NetBeans. (Or, as I keep saying, just use HTTPS and a password.) Make sure the URI is correct; if using SSH, make sure the Username field is filled with “
src” project folder. Click Next.
mypkg/Main.javashows in the list of included files. Then click the Finish button.
If you only see “
Main.java” and not
mypkg/Main.java”, then you didn't
have the correct folder selected in the previous step.
In this case, hit the “Back” button, click on the folder
to select it, and hit the “Remove” button.
Now click the “Add folder...” button and try again.
src→mypkgpackage (folder) to see the “
Main.javaand add your code. Make sure the code will compile and run, and displays your greeting along with the other greetings from your fellow classmates.
With Eclipse, right-click on your project and select
“Show in History”.
The Master branch's HEAD should be the commit with your change in it.
Right-click on that commit in the history, and select
File to save your patch (a pull request) in a file;
the default name of the file defaults to the first line of your commit
message, but you can change that if you wish.
Now you can choose a patch file format. Eclipse can only apply
patches made in the “Eclipse workspace” format, but for
this project use the standard “Git (e-mail header)”
With NetBeans, with the
showing, click on Team→Show History.
The Master branch's HEAD should be the commit with your change in it.
Click on the box with the plus-sign, to expand your choices.
Now click on “
Export Commit...” to make a
patch file (a pull request).
Save it someplace (say, on your desktop) with a descriptive name, something
like “hpiffl pull request”.
You should examine your patch file in a text editor. Your IDE can show it to you with color and syntax highlights. See if you can understand the format; someday you may wish to tweak one of these files before sending off the email.
(View a Sample Patch File.)
If you opened the project a while ago, others may have made changes. In this case, Git won't be able to automatically merge the changes, since both changes were to the same file. (The error message will say something about fast-forward failed.) You must Fetch the new commit(s) into your local repo, then Merge your changes with those (locally). Both Eclipse and NetBeans have nice merging tools; they work best with a wide-screen monitor. After reconciling the differences (and testing to make sure the code still runs), you complete the merge with a commit. Then you can Push that merge commit to GitHub without problems.
You should explore some of the other items on the “Team” menu. You are encouraged to create branches and play with them. Note that only the Master branch of the class' Github repo will be graded. When finished with this project, right-click on the project and close it. (This should help prevent “accidents”.)
Try creating your own repo on Github.com.
I suggest you check the box to create an initial
Without at least one commit in it, it isn't possible to clone a repo.
(You can push to it however.)
Adding this file means you can clone the repo easily.
From the repo's settings page, you can delete a repo when you are done with it (or after you messed it up badly, and want to just start over). You can create as many repos as you like on Github. They are all public unless you pay money for a private repo. (That means anyone can clone and view it; but only you and those you add as collaborators can push changes to it.)
Working with a local repo is easier than working with a remote one. You can create a new project and share it using your IDE's Team menus. This will create a local Git repo, for your project only. With this, it is easy to practice making many commits, checking out old ones, creating branches, and merging branches. Since you only are using a private, local repo, there is no Push or Fetch (Pull) to worry about.
If you mess up working with your IDE and want to start over, that is easy too. Simply delete the project (including all files) from the IDE. Next, find the Git repo created on your computer for that project; it is separate from the IDE's project folder (usually). Then delete that too. Now you can import the Git repo from Github again, and create a new project.
Please spend some time exploring the Git resources from our class web site. They can really help, and I promise Git has many more features than you will use on this simple project. Try not to forget the purpose of this project: to spend time learning Git.
NetBeans can use SSH keys,
but can't generate them.
You will need additional software to create a pair of keys, each in a
You then tell NetBeans the name of the file with the (private) key.
You can use the keys generated by Eclipse, or by the
tool that comes with
or Git for Windows.
Launch the Bash (command line) window, and follow
the directions from
Git-SCM.com/.../Generating-Your-SSH-Public-Key or from
Eclipse can generate and use SSH keys:
wpollock@home” or “
wpollock-ssh-key”), and also save the public key in a similarly named file (in this case, “
wpollock-ssh-key.pub”). You don't have to password protect your private key, but keep in mind anyone or any malware with access to your computer can use that key! So best practice is to password protect your private keys with good passwords. Make a note of the files location. Make an off-line backup of the files as well.
• Keys cannot be recovered if lost.
Make sure you have a good backup copy (or two).
• Use of your private key may have legal implications. Either protect your private key with a strong password, or don't use that key for any other purpose.
To test your key, follow the directions at help.github.com/articles/testing-your-ssh-connection.
If you have trouble using keys, remember you can use
HTTPS protocol instead (with a password).
You can also ask your instructor for help.
Email a copy of your pull request (patch file), by copy and paste, showing your
Main.java Java source code additions.
(No credit if your changes aren't found on the Master branch of the class
Github repo, or if you don't use an IDE to make the changes.)
You can send as email to
If email is a problem for some reason, you can submit the patch as an
attachment, or you may turn in a hard-copy.
In this case the pages should be readable, dated, and stapled together.
Your name should appear on the first page.