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AP Computer Science A

Tips

AP Computer Science A is a Java course: objects and classes, primitive types and control flow, writing classes, arrays and ArrayLists, 2D arrays, inheritance and polymorphism, and recursion. It is a first programming course taught with real object-oriented code, not pseudocode.

All four free-response questions are hand-written Java. No compiler will catch a missing semicolon or a wrong return type for you, so write code on paper during revision — it is a different skill from typing it.

Arrays and ArrayLists are the most-tested topic. Being fluent with traversal, insertion and removal, and knowing which index shifts when you remove an element, pays back more than any other single hour of practice.

Notes cover the CED units in Java, with runnable examples you can edit in the browser. Past FRQs and scoring guidelines are in the library — all four are code-writing questions, so the worked answers are complete methods rather than fragments.

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Past Papers
  • 1

    Using Objects and Methods

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    • 1.1 Introduction to Algorithms, Programming, and Compilers
    • 1.2 Variables and Data Types
    • 1.3 Expressions and Output
    • 1.4 Assignment Statements and Input
    • 1.5 Casting and Range of Variables
    • 1.6 Compound Assignment Operators
    • 1.7 Application Program Interface (API) and Libraries
    • 1.8 Documentation with Comments
    • 1.9 Method Signatures
    • 1.10 Calling Class Methods
    • 1.11 Math Class
    • 1.12 Objects: Instances of Classes
    • 1.13 Object Creation and Storage (Instantiation)
    • 1.14 Calling Instance Methods
    • 1.15 String Manipulation
    • 1.15 Exam tips
  • 2

    Selection and Iteration

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    • 2.1 Selection and Repetition in Algorithms
    • 2.2 Boolean Expressions
    • 2.3 The if Statement
    • 2.4 Nested if Statements
    • 2.5 Compound Boolean Expressions
    • 2.6 Comparing Boolean Expressions
    • 2.7 while Loops
    • 2.8 for Loops
    • 2.9 Building Complete Selection and Iteration Algorithms
    • 2.10 String Algorithms
    • 2.11 Nested Iteration
    • 2.12 Informal Run-Time Analysis
    • 2.12 Exam tips
  • 3

    Class Creation

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    • 3.1 Abstraction and Program Design
    • 3.2 The Impact of Program Design
    • 3.3 The Anatomy of a Class
    • 3.4 Constructors
    • 3.5 Methods: How to Write Them
    • 3.6 Passing and Returning References of an Object
    • 3.7 Class Variables and Class Methods
    • 3.8 Scope and Access
    • 3.9 The this Keyword
    • 3.9 Exam tips
  • 4

    Data Collections

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    • 4.1 The Ethics of Collecting Data
    • 4.2 Why We Need Data Structures
    • 4.3 Making and Reading an Array
    • 4.4 Visiting Every Element of an Array
    • 4.5 Standard Array Algorithms
    • 4.6 Reading Data from a Text File
    • 4.7 Wrapping a Number in an Object
    • 4.8 The ArrayList Toolbox
    • 4.9 Visiting Every Element of an ArrayList
    • 4.10 Standard ArrayList Algorithms
    • 4.11 Grids: Two-Dimensional Arrays
    • 4.12 Walking Through a Grid
    • 4.13 Standard 2D Array Algorithms
    • 4.14 Finding a Value: Linear and Binary Search
    • 4.15 Putting Data in Order: Selection and Insertion Sort
    • 4.16 Methods That Call Themselves: Recursion
    • 4.17 Recursive Search and Merge Sort
    • 4.17 Exam tips

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