Unit 04

Data Collections

Build four things that each hold thousands of values at once — a dataset you parse, a photograph you edit pixel by pixel, a playable 2048 and a sorting bench — and learn the arrays, ArrayLists, 2D arrays and algorithms underneath all four.

30–40% of the AP Exam~50–52 CED periods~25–29 blocks here17 topics

AP Computer Science A · members' unit

Data Collections is behind a locked door

Units in AP Computer Science A are for people taking the course. Getting in takes a link or a key — signing in on its own doesn't do it.

What's in this unit · 42 min read

  1. What you will build
  2. 4.1 · Ethical and social issues around data collection
  3. 4.2 · Introduction to using data sets
  4. 4.3 · Array creation and access
  5. 4.4 · Array traversals
  6. 4.5 · Implementing array algorithms
  7. 4.6 · Using text files
  8. 4.7 · Wrapper classes
  9. 4.8 · ArrayList methods
  10. 4.9 · ArrayList traversals
  11. 4.10 · Implementing ArrayList algorithms
  12. 4.11 · 2D array creation and access
  13. 4.12 · 2D array traversals
  14. 4.13 · Implementing 2D array algorithms
  15. 4.14 · Searching algorithms
  16. 4.15 · Sorting algorithms
  17. 4.16 · Recursion
  18. 4.17 · Recursive searching and sorting
  19. The projects, in full

43 quick checksvideoArrayList sandboxloop tracercall stack viewerarray explorer+2 more

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With your school Google account. This is how your work reaches the gradebook — it doesn't open the unit by itself.

2 Get in

Open the class link your teacher posted — that's the usual way, and it enrols you on the spot. Or paste an access key if you were handed one.

A key unlocks this browser and keeps your progress here; signing in keeps it with you across devices. Either way the key itself is only ever checked as a hash. Manage all of this on your account, read what signing in stores, or go back to AP Computer Science A.

Sources

  • College Board — AP Computer Science A Course and Exam Description, Effective Fall 2025
  • Gilmour Academy — Course structure and standards adaptation