Programming Assignment 6

Due Date: Tuesday, February 21, 10:00PM Pacific Time

Learning Goals

This PA will give you an opportunity to reflect on how you work through programs.

Collaboration

Different assignments in this course have different collaboration policies. On this assignment, you cannnot collaborate with anyone. Your submission must be your own work and you cannot share or post code from your submission anywhere other than to hand in the assignment.

The starter code is available at:

https://github.com/ucsd-cse11-w23/cse11-pa6-starter

Submission checklist

[ ] PDF to Gradescope assignment pa6-notes
[ ] Two code files for completed tasks to pa6-code (just two of four programs need to be completed)

Task

Make a copy of this Doc. You will fill it in as you work.

Your task is to complete two of the following programs of your choice, and also complete a reflection while you are working.

When you’re ready to start programming, set a timer for 30 minutes – work on these tasks for that much time. Then, take a screenshot or copy/paste (a) your code and (b) the output of the most recent time you ran the program. It’s totally fine if running your code is producing errors at this point, the idea is just to take notes on progress.

Put that output into the Google Doc at the 30 minute mark, and write down a few sentences about your thought process at this point. Also note if you got distracted by another browser tab, your phone, etc during that 30 minutes. You don’t have to tell us how, just say yes/no and how many minutes you think you were distracted for.

When you work again, set another 30 minute timer and work for that time, then repeat taking notes. Then do this one more time, for a total of three 30 minute sessions each followed by note-taking.

If you don’t finish the task, still stop after the three sessions and put the notes for the reflection in place (it’s not expected that you must finish in 90 minutes, though you do have to finish, see below). If you finish early, note the time you finished.

The tasks, which you should complete two of, are here:

In a file called AveragePositives.java, write a class with a main method that expects all the command-line arguments to be appropriate inputs to Double.parseDouble. It should print the average (mean) of the command-line arguments that, when parsed as doubles, are strictly greater than 0. If there are no numbers in the array that are greater than 0, it should produce 0.

Try out at least six different uses of AveragePositives at the command line with different lists of numbers that convince you it works for all of the important cases.
In a file called PairSelect.java, add a class Pair with fields a and b of type int (add a constructor to initalize those fields). In a class called PairSelect, write a method getAs that takes an array of Pair and returns an array of int that contains the a field of all the Pairs in the array given as an argument. Write at least 4 checkExpect tests for it to cover interesting cases.
In a file called LongStrings.java, write a method called longStrings that takes an array of String and an integer n and produces a new array of Strings that are just the strings in the array that have length n or greater (the returned array might be shorter than the input array). Write at least 4 checkExpect tests for it to cover interesting cases.
Copy the Point class from the regions code in lecture into a new file called ClosestPoints.java. Write a class called ClosestPoints with a main method that expects to get six command line arguments, representing the x and y coordinates of three points. For example:
```
  $ java ClosestPoints 0 0 3 4 3 900
```
Would represent the points (0, 0), (3, 4), and (3, 900). Your program should print out the pair of points that are closest to one another out of the three points, using the format below:
```
  $ java ClosestPoints 0 0 3 4 3 900
  The closest points are (0, 0) and (3, 4) at distance 5.0
```

Reflection

After you’re done with all three sessions (not necessarily the whole assignment), reflect on the following:

Where did you spend the most time? You might have different descriptions, some I can think of that I spend a lot of time on are below; you might have others.
- Thinking about a particular part of the program
- Understanding an error message
- Figuring out why a particular test wasn’t working
- Typing
What could you do to reduce the time taken in the future?
How did this process compare to how you usually complete PAs?
Overall, what did you learn from this experience about your programming workflow, if anything?

Some comments on this process: this may not be the ideal way for you to work. Sometimes I get a lot of “programming” done while walking my dog, and sometimes setting a problem down for a while and coming back to it is the best thing. You might be working on a day where other urgent obligations interrupt you every 5 minutes. Sometimes you may need to focus really hard for several hours to make any progress. So I don’t expect that you can or should always follow this process. However, doing it once might give you a useful scaffolding strategy, and it does help you understand how your time management and focus works while you’re programming, where you got stuck, etc. So for that reason I think this is a really useful exercise.

Finishing

You must still finish these programs as part of the assignment. There is no autograder for them released while the assignment is out; we will grade them manually after the deadline. Come ask for help in tutor hours (help sessions) if you need help finishing them! We do ask that you spend at least one 30-minute session with notes before coming to help sessions on PA6, and we might ask to see your notes for a sense of your progress when you come.

Submission

Export your notes document as a PDF using Google Docs (under the File menu). You’ll hand it in under the pa6-notes assignment on Gradescope.

You’ll hand in the two .java files with your completed tasks to the pa6-code assignment on Gradescope.

Challenges and Extra Practice

If you want more practice or an extra challenge, try writing the programs below. These are not for credit, but feel free to ask us about them on Piazza if you found them interesting!

Make ClosestPoints work for any number of points input on the command line.
Write a method zip that takes two arrays of int that have the same length and produces an array of Pair where the Pair’s a and b fields are the values in the corresponding index in the first and second provided int array.
Write a method unzip that takes an array of Pair and returns two arrays, one containing the a elements and one containing the b elements. Decide how to represent the return value yourself.

FAQ

You only need to finish/submit 2 of the 4 tasks, and pa6-code assignment on Gradescope is due on the same day as pa6-notes (August 25th).
Q: In AveragePositives.java, is the number of values that we average over all the numbers passed as command line arguments or just the positive numbers?
- A: We are only considering positive numbers. So for both the total and the count they should only be of the positive numbers.