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CSC 207.01 2019S, Class 03: Getting started with Java development


  • Preliminaries
    • Notes and news
    • Upcoming work
    • Extra credit
    • Questions
  • Quiz
  • Eclipse lab
  • Git lab


News / Etc.

  • We’ll follow the new partner methodology.
    • Partner names on the board.
    • See email about “Do not partner me with” option.
  • Please turn in your academic honesty policy if you have not done so already.
  • If you’re not on the csstudents list, you probably should be. Let me know if you’d like to be added.
  • Mentor sessions at 7:00 p.m. Sunday nights.
  • You will have a substitute teacher on Wednesday. I’ll be off learning about Fairness, Accountability, and Transparency in Artificial Intelligence.
  • If you feel unsafe coming to class on Wednesday, send me an email message and I will treat it as an excused absence. You are, however, responsible for making up the work on your own.
  • When you send me questions about assignments, please title them things like “QUESTION on Assignment 2”. It makes it much easiere for me to identify them as questions.
  • In case it wasn’t clear from the syllabus and such, I will randomly call on students in class. I do this for multiple reasons.
    • It avoids bias (conscious and unconscious). Since I’m using cards, I am unlikely to ask more questions of people from certain groups.
    • It builds skills. For better or for worse, many people expect you to express your ideas, even when you have not formulated them completely. Practice in a low-stakes environment should help.
    • It can remind you that you are not alone in confusion or misunderstanding. While I may sometimes force you to guess, you can feel free to answer “I’m not sure” when I call on you.
    • It sometimes incentivizes you to ask questions. If you know that I might ask you questions, you may be more inclined to ask me questions.
    • And more.
  • If being called on in class causes severe anxiety, let me know and we’ll figure out a way to adjust to support you.
  • I’ve updated the due time for lab writeups; writeups are generally due at the start of class.
  • You should be able to access everything on the current eboard by substituting .md for .html at the end of the URL.

Upcoming work

  • Assignment 1 due Thursday night.
  • Reading due before class Wednesday.
    • Osera, Chapter 2
  • No lab writeup for Monday’s class.

Extra credit

Extra credit (Academic/Artistic)

Extra credit (Peer)

Extra credit (Wellness)

  • Kindness through gratitude, Monday and Tuesday 11-1, outside DHall.

Extra credit (Misc)

Other good things


Tell me about the organization of a Java program

Java programs consist of multiple classes that work together.

Each class (normally) resides in its own file. More precisely, each public class has to be in its own file; you can add private classes to a file with a public class.

By default, Java programs need a public, static, main, that takes an array of strings as parameters.

We use the main method that appears in the command when you start the Java program. java HelloWorld means “run the main method in the HelloWorld class.

That main method (and other methods) can … (a) run “normal” code; (b) call static methods in the same class; (c) call static methods in other classes with ClassName.method; (d) create objects with new ClassName(params); (e) call methods on those created objects.

For levels of groups, Java also supports packages (a group of classes) and modules (a group of packages). We will not use modules, which were just introduced.

Can you have a method that’s not static?

Yes. Just don’t write the word static. That method will then require that you create an object and it can use the fields and methods of that object. (See Wednesday’s class.)

How should we format code?

See the Google Java Style Guide.

Our goal is consistency, which helps readers (and writers) (and graders).


Fun and a chance for all of us to learn a bit. (More or less.)

Eclipse lab

  • Computers are sentient and malicious!

Git lab

What should commit comments look like?

A note that will remind you what you just did.

“Add the HelloWorld class.”

“Prepare the project for use in Eclipse.”

“Squash the bug."

“Refactor the code in HelloWorld.”


Things Eclipse gives you …

  • On-the-fly syntax checking. (You’ll see a red x at the left.)
  • Contextual documentation.
  • Some automation (e.g., for refactoring, moving files).
  • Enough that it overwhelms some folks.
  • Lots of warnings on the command line.

Things Git gives you …

  • An easy way to share code.
  • A history of your project.
  • Ways to see changes.