Creating a Jar File

Once you have successfully completed your programming assignment, you will need to create a Jar file to submit your assignment to Blackboard. This will help us grade your assignment. You will lose points if you do not submit your programming assignments in a Jar file.

Instructions for checking your Jar file

What's a Jar File?

Jar stands for "Java Archive". It's much like a compressed ZIP file that you may have used before. You'll be adding each Java source file in your assignment (usually only one file) to a Jar file before submitting it on Blackboard.

Why Do I Have to Create a Jar File?

When your programming assignments are downloaded, Blackboard automatically prepends the program number and your Onyen to the filename of the Java source file you've submitted. Remember that Java requires that the file name of the Java source code and the main class name be the same. This renaming by Blackboard causes us to be unable to compile your assignment.

If you create a Jar file that contains the appropriately named Java source file, Blackboard will rename only the Jar file, not the Java source file. This allows us to easily compile and run your program.

How Do I Create a Jar File?

After you've successfully compiled, run, tested, and commented your program, choose New...Standard Project from the Project menu in jGRASP.
You will be offered the opportunity to add java files to the project.
Add the appropriate one (or ones). Then complete. You should see the project
open in jGrasp, as below.

After you've successfully compiled, run, tested, and commented your program, choose Create Jar File For Project... from the Project menu in jGRASP.

The Create Jar File for Project (default) window should open. Select the checkbox marked 'sources.' The top box may already include your java file. Click Add to choose your Java source files for the current assignment if they are not included already.

A file dialog box will open. Choose each file you want to add to the Jar file and click Add. You should add only the Java source files (ending in .java). Once you have added the files, click Cancel in the file dialog box.
After the file dialog box closes, you should be back to the Create Jar File for Project (default) window. The files that you have added should be displayed in the "Additional (non-project) Files" list. After you have double-checked that you have added the appropriate files, click Next to continue creating the Jar file.

A new window will open asking for the name of the Jar file to create. You should name the file progN_onyen.jar, where N is the programming assignment number and onyen is your Onyen. Make sure that the Jar file ends in .jar and that the file is being created in the same folder as your Java source files. Once you have appropriately named your Jar file, click Create Jar.

After the Jar File has been created, click the R button in the Browse window to the left. This will refresh the list of files in your current folder. Your newly-created Jar file should appear in the list.

If you have problems creating a Jar file, contact me.

How Do I Check to Make Sure My Jar File is Correct?

After you've completed the steps above, your Jar file should appear in the list of files on the left side of your jGRASP window.
Choose Jar/Zip Extractor... from the Project menu.
In the Jar/Zip Extractor window, click on the folder icon.

In the Open File window, chose the Jar file that you just created and click Open.

If you see the name of your Java source file in the Jar/Zip Extractor window, you have successfully created your Jar file. (You may also see some other files, like "META-INF" and "MANIFEST.MF" in the window.) Double-check the "Modified" date to make sure that you've put the latest version of your Java source file in the Jar file.

When you submit your assignment using Blackboard, you only need to attach the Jar file.