AP CSA Exam Center

AP Exam Center

This section is for assessment practice rather than new instruction. Use it after students have worked through the unit pages.

Trace variables, loops, method calls, arrays, ArrayLists, and objects. Require students to show a table of values.

Find the bug, explain the bug, and fix the bug. The explanation matters as much as the correction.

Organized by Methods, Classes, ArrayLists, and 2D Arrays.

Type	What Students Write	Common Mistakes
Methods & Control	Methods using conditionals, loops, accumulators, and helper methods.	Missing return values, wrong loop bounds, integer division.
Class Design	Instance variables, constructors, methods, and toString.	Forgetting private fields, constructor errors, direct field access.
ArrayList	Search, filter, remove, insert, and rank objects.	Skipping elements after removal, using array syntax.
2D Array	Nested loop traversal, row/column totals, grid searches.	Confusing rows and columns.

Tracing: Loops

int total = 0;
for (int i = 1; i <= 4; i++) {
    total += i * 2;
}
System.out.println(total);

Answer: 20.

Debugging: ArrayList Removal

for (int i = 0; i < list.size(); i++) {
    if (list.get(i) < 0) {
        list.remove(i);
    }
}

Problem: removing while moving forward can skip values. Fix by moving backward or decrementing i after removal.