Unit 4 Cycle 1 Day 28: Comprehensive Unit 4 Review

February 18, 2026

Unit 4 Foundation (Cycle 1) Day 28 of 28 Foundation

Comprehensive Unit 4 Review

Section Mixed — Review: All Unit 4

Key Concept

This comprehensive Unit 4 review covers arrays, ArrayList, searching, sorting, and 2D arrays. Unit 4 represents approximately 17-22% of the AP CSA exam. The most commonly tested topics are: ArrayList removal during traversal (the forward removal bug), binary search tracing, selection and insertion sort step-by-step execution, 2D array row-major traversal, and the difference between array and ArrayList operations. Free-response questions frequently involve array and ArrayList manipulation.

Consider the following code segment.

ArrayList words = new ArrayList(); words.add("the"); words.add("quick"); words.add("brown"); words.add("fox"); String longest = words.get(0); for (String w : words) { if (w.length() > longest.length()) { longest = w; } } System.out.println(longest);

What is printed?

Answer: (B) "quick"

Lengths: "the"=3, "quick"=5, "brown"=5, "fox"=3. longest starts as "the". "quick"(5)>3: longest="quick". "brown"(5) is NOT > 5. "fox"(3) is NOT > 5. Result: "quick".