title: "AP Computer Science A 3-Day Cram Plan" description: "A focused 72-hour AP CS A rescue plan: core Java syntax, object-oriented patterns, array traversal, and FRQ templates to maximize your score before exam day." date: "2026-01-15" examDate: "May AP Exam" topics:
- Primitive Types & Variables
- Objects & Classes
- Arrays & ArrayLists
- Iteration & Traversal
- Inheritance & Polymorphism
You have three days until the AP Computer Science A exam. This is not the time to learn recursion from scratch — it's time to drill the highest-frequency Java patterns and lock in the FRQ templates the College Board reuses every year.
This plan assumes ~4 focused hours per day. Skip nothing on the checklist; if you're short on time, shorten the practice sets, not the topic coverage.
Day 1: Primitives, Objects, and Classes (4 hrs)
The first ~20 multiple-choice questions lean on understanding variables, objects, and how to write methods.
What to review (90 min)
- Primitive types:
int,double,boolean— declaration, initialization, assignment. - Integer division and modulo:
7 / 2 = 3,7 % 2 = 1. This trap appears on almost every exam. - String methods:
.length(),.substring(),.indexOf(),.compareTo(),.equals()vs==. - Math class:
Math.abs(),Math.max(),Math.min(),Math.pow(),Math.random(). - Writing a class: constructor, instance variables,
thiskeyword, instance methods, static variables. - Scope and visibility:
public,private, local variables inside methods.
What to practice (2.5 hrs)
- Write 3 simple methods: one that uses integer division, one that manipulates a String, one that uses
Math.random(). - Write 1 complete class with a constructor and 2 instance methods.
- 15 multiple-choice on primitives and object instantiation.
💡 Highest leverage: Integer division mistakes appear on every exam. Drill 5 problems where you compute
a / banda % btogether.
Day 2: Arrays, ArrayLists, and Traversal (4 hrs)
These two structures account for nearly half of all AP CS A points. You must know both forwards and backwards.
What to review (90 min)
- 1D Arrays: declaration (
int[] arr = new int[10]), access, traversal with for-loops. - Common array algorithms: find max/min, sum all elements, count matches, swap, reverse.
- ArrayList basics: add, remove, get, set, size — and that ArrayList uses generics (
ArrayList<Integer>notArrayList). - Traversal patterns: enhanced for-loop vs index-based for-loop vs while-loop.
- The remove trap: removing during iteration can skip elements; use
remove(index)carefully. - 2D arrays: row-major order, nested for-loops, accessing
arr[row][col].
What to practice (2.5 hrs)
- 1 FRQ-style problem: write a method that takes an array and returns the index of the max element.
- 1 FRQ-style problem: write a method that takes an ArrayList, removes all even numbers, and returns the size.
- 1 2D array problem: write a method that sums all elements in a 2D array.
- 20 multiple-choice on arrays and ArrayLists.
⚠️ FRQ trap: When removing from an ArrayList during iteration, your index will skip elements. Either iterate backwards, use an iterator, or build a new ArrayList instead.
Day 3: Inheritance, Recursion, and Full FRQ Timed Practice (4 hrs)
What to review (90 min)
- Inheritance:
extendskeyword,super()call in constructor, method overriding. - Polymorphism: a subclass object in a superclass variable, calling overridden methods.
- The Object class:
.equals(),.toString(),.hashCode()— know what you're overriding. - Recursion basics: base case, recursive case, the call stack, tracing a recursive method by hand.
- Common recursive patterns: factorial, sum of array, binary search.
What to practice (2.5 hrs — full timed set)
- Trace 2 recursive methods by hand (write out 5-7 steps of the call stack).
- Write 1 recursive method (e.g., sum of an array, or count a character in a string).
- 1 full FRQ timed (methods and control structures, 10 min).
- 1 full FRQ timed (class design with inheritance, 10 min).
- 25 mixed multiple-choice (high-frequency topics), strictly timed.
💡 Recursion on Day 3: If you're weak on recursion, spend 30 min here and accept you may lose 2-3 points. Don't sacrifice array mastery to learn recursion from scratch.
The night before
Skim our last-minute review checklist. Get 8 hours of sleep — tomorrow your brain must parse Java syntax cleanly, and fatigue turns == into .equals() blindness.
Common point-leaks (prevent these)
- Using
==to compare Strings instead of.equals(). - Integer division instead of casting to
doublebefore division. - Forgetting to return from a method.
- ArrayList remove during a forward iteration (skip next element).
- Off-by-one errors in array loops and substring calls.
- Null pointer exceptions from accessing uninitialized objects.
What this 3-day plan deliberately skips
You will not fully master advanced recursion patterns or deep inheritance hierarchies in 3 days. If you're shaky there: do 2 worked examples, trace 1 complex recursive call, and accept you may lose a few points. Spend the saved time mastering array traversal and basic class design instead.
Ready to start?
Open the AP Computer Science A topic library → and start with Day 1 if you're weak on classes, or Day 2 if you're weak on arrays. Mix in 2-3 FRQ practice problems. You've got this.
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