AP Computer Science A — Java Fundamentals flashcards

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Units 1–2 of the revised AP Computer Science A course: types and casting, integer division and modulus, precedence, String and Math methods, boolean logic and De Morgan's laws, short-circuiting, if/else, loops, tracing and off-by-one errors.

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Learn deck · part of AP Computer Science A · written against: College Board AP Computer Science A Course and Exam Description (Java subset; 2025 revision). Updated 2026-10-10.

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Which three primitive types does AP Computer Science A work with, and what kind of value does each hold?

int holds whole numbers, double holds numbers with a fractional part, and boolean holds true or false.
Using Objects and Methods › Primitive Types and Casting
What value does (int) 7.9 produce?

7. Casting a double to an int truncates: the fractional part is simply dropped, with no rounding.
Using Objects and Methods › Primitive Types and Casting
What value does (int) -7.9 produce, and why is it not -8?

-7. Truncation always moves toward zero, so a negative value moves up rather than down.

Watch out: a cast is not the same as rounding down.
Using Objects and Methods › Primitive Types and Casting
Using only a cast, how do you round a positive double named x to the nearest int?

(int) (x + 0.5). Adding one half before truncating pushes values with a fractional part of .5 or more up to the next integer; for a negative x, use (int) (x - 0.5).
Using Objects and Methods › Primitive Types and Casting
What do (double) 7 / 2 and (double) (7 / 2) each evaluate to?

3.5 and 3.0. A cast binds more tightly than division, so in the first expression 7 becomes 7.0 before dividing; in the second, integer division produces 3 first and only then is it widened.
Using Objects and Methods › Primitive Types and Casting
What are De Morgan's laws written as Java boolean expressions?

!(a && b) is equivalent to !a || !b, and !(a || b) is equivalent to !a && !b. Negating flips each part and swaps && with ||.
Selection and Iteration › Boolean Logic
Using De Morgan's laws, what is an equivalent expression for !(x > 5 && y <= 3) with no !?

x <= 5 || y > 3. Each comparison is negated and && becomes ||.
Selection and Iteration › Boolean Logic
What is the negation of x >= 10?

x < 10.

Watch out: x <= 10 is wrong, because 10 satisfies both x >= 10 and x <= 10.
Selection and Iteration › Boolean Logic
What is short-circuit evaluation for && and ||?

Java stops as soon as the result is known: with &&, if the left side is false the right side is not evaluated; with ||, if the left side is true the right side is not evaluated.
Selection and Iteration › Boolean Logic
When x is 0, does evaluating x != 0 && 10 / x > 1 throw an exception?

No. The left side is false, so short-circuit evaluation skips 10 / x and the whole expression is simply false.
Selection and Iteration › Boolean Logic

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Review status: Second-reader reviewed, with corrections applied.

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Topic outline follows the College Board AP Computer Science A Course and Exam Description (revised course, first exam May 2026), Units 1–2 (the AP name is used nominatively; no course or exam text reproduced).
Every code trace was checked by compiling and running the equivalent Java (OpenJDK); behavior checked against the Java SE API documentation (reference only, no text copied).
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