CSC207.01 2014F, Class 09: Some Basic Types: Numbers and Strings in Java

Overview

Preliminaries

Continue partners.
I'll try not to talk much today (after the preliminaries and discussion of testing).
Any remaining pic-i-nic tick-e-ts?
One of the strange aspects of Java is how Java converts between primitive types and equivalent objects. (These conversions are called "boxing and unboxing".) You'll see a bit about them today and then read about them over the weekend.
Anyone else for the CS Students Mailing List? (Email me and I'll add you.)
Another Walker/Rebelsky difference: Output
- Walker prefers System.out, presumably because it's simpler.
- Rebelsky prefers that you use java.io.PrintWriter objects because
  - it encourages you to think more in terms of objects; and
  - it makes your code more adaptable (e.g., something that prints to the screen can be easily converted to something that prints to a file or ...).
- I'll note that I'm in the minority among my departmental colleagues.
I tried to compress two shorter labs into one day. It's probably too much, even with some effort to move things out of each lab. The most important problems are exercise 7 on the basic types lab and exercises 2 and 7 on the I/O lab.
Things faculty do.. about 90 of us are getting together at lunch today to discuss the future of liberal arts education, using Remaking College as the basis of our discussions.
It's weekend. Please reflect in advance on what decisions will be appropriate for you. And if you choose to drink, please drink responsibly.

Only half of you filled them out. Prologues and epilogues are required.
Range of time: 4 to 13 hours.
- Computer programmers work at very different rates.
- I hope that groups even things out.
- Please use resources to help keep time reasonable.
"My biggest problem was that I wasn't familiar with Java."
- You weren't supposed to be familiar with Java.
- I tried to mostly focus on problems you should be able to design in C, so you could think about how to express them in Java.
- I appreciate that you're working on skills in lifelong learning, but one such skill is asking for help.

Daily lab writeup: http://bit.ly/207writeup
Readings for Monday:
- Refernece Values in Java
- Automatic Boxing and Unboxing in Java
Peer review of HW3 (due Tuesday):
- http://bit.ly/207-2014F-peer03.
- I'll email the individual associations later today.

Project IGNITE!
Second-year students get extra credit for doing the second-year science retreat on Sept. 20.
Second-year students also get extra credit for filling in the email survey. (Please don't just email "I took the survey.")

HW4 Concerns seem split between the calculators and the CSV.
- Past history suggests that these are the most difficult parts.
- Note that you can assume we have spaces between things in the calculator. (But I wouldn't suggest you use String.split.)
Eclipse and Git are not working together.
- Create repository on GitHub, include a readme.
- Clone it onto MathLAN (or other computer)
- Start Eclipse
- New project -> Use directory (clone) -> Cross fingers
- In the directory, git add ., git commit, git push
Please print more open source surveys for Monday.

I like doing lots of randomized tests. How do you design a randomized test? Often, you start with the answer and then work backwards.

For average: Pick a random number, r, between Integer.MIN_VALUE/2 and Integer.MAX_VALUE/2. Pick another random number, o, between 0 and Integer.MAX_VALUE/2. average(r+o, r-o) should be r.
- Yes, we need to do a little bit more playing to explore the averages with a fractional component.
For sort: Build a sorted array. Permute it. Sort it. See if you get something equivalent to the original array.

You should also consider the likely edge and corner cases, typically involving extremes.

Systematic tests are also great. We'll look at a systematic test for binary search.