Store and process groups of data. Master arrays, 2D arrays, and ArrayList; traverse them with loops; read from text files; use wrapper classes; and apply the standard searching, sorting, and recursion algorithms. This is the largest unit on the exam.
Six ways to master Unit 4 — pick whichever fits how you like to study.
All 17 topics from the College Board CED, in order.
Unit 4 is about storing and processing collections of data — and at 30–40% of the exam it is by far the largest unit. You start with the ethical and social issues of data collection, then learn the three core structures. An array is a fixed-size, indexed collection (indices 0 to length−1); an ArrayList is a resizable list with methods like add, get, set, remove, and size; and a 2D array is a grid accessed by row and column.
For each, you write traversals (standard for loops and the enhanced for-each loop) and standard algorithms — finding a min/max, summing, counting, and filtering. You’ll read data from text files with a Scanner and use wrapper classes (Integer, Double) with autoboxing. The unit finishes with the classic algorithms: sequential and binary search, selection and insertion sort, and recursion — methods that call themselves, including recursive binary search and merge sort.
This unit takes about 50–52 class periods and is central to the Data Analysis free-response question. The five computational thinking practices below run through every topic: