AP Computer Science A:: Array Flashcards (50 Cards) — Study Online

Curriculum Overview

Comprehensive, high-yield AP Computer Science A study deck focusing on Array. Features 50 rigorous, curriculum-aligned flashcards designed for intermediate-level mastery. Core concepts covered include Array, key problem-solving heuristics, foundational formulas, and exam-tested application scenarios. Ideal for active recall review, spaced repetition study, and scoring in the top percentile.

Topics & Key Concepts

Each Java This Array INDEX Index Arrays Binary SEARCH String

Sample Flashcard Questions & Answers

Showing 8 of 50 cards

Question #1 Active Recall

What is an ARRAY in Java?

- **A)** A fixed-size collection of elements, ALL of the SAME data type, stored in contiguous memory and accessed by numeric INDEX
- **B)** A collection whose size can grow or shrink freely after creation
- **C)** A collection that can hold elements of many different types simultaneously
- **D)** A synonym for a single primitive variable

Answer & Explanation:

**Answer: A)**

Arrays are fixed-size, single-type collections -- a foundational data structure that later collections like ArrayList (Unit 7) build upon and extend.

Question #2 Active Recall

Which line of code correctly declares and creates an array of 10 \(int\) values?

- **A)** \(int\ arr[10];\)
- **B)** \(int[]\ arr\ =\ new\ int[10];\)
- **C)** \(int\ arr\ =\ new\ int[10];\) (missing \([]\))
- **D)** \(array\ arr\ =\ new\ int(10);\)

Answer & Explanation:

**Answer: B)**

The standard array-creation syntax uses \([]\) after the type in the declaration, and \(new\ type[size]\) to actually allocate the array.

Question #3 Active Recall

What are the valid INDEX values for an array of length 10, declared as \(int[]\ arr\ =\ new\ int[10];\)?

- **A)** \(-9\) through \(0\)
- **B)** \(0\) through \(10\)
- **C)** \(0\) through \(9\) (10 total valid indices)
- **D)** \(1\) through \(10\)

Answer & Explanation:

**Answer: C)**

Java array indices always start at 0, so an array of length \(n\) has valid indices \(0\) through \(n-1\).

Question #4 Active Recall

What does \(arr.length\) return for an array \(arr\)?

- **A)** The value stored at the first index
- **B)** The total NUMBER of elements the array can hold (its fixed size), NOT the index of its last element
- **C)** \(arr.length\) is a method call requiring parentheses: \(arr.length()\)
- **D)** The index of the last valid element

Answer & Explanation:

**Answer: B)**

\(length\) is a FIELD (not a method, so no parentheses) that gives the array's total capacity; the last valid index is always \(length - 1\).

Question #5 Active Recall

What happens when code attempts to access an array index that is OUT OF BOUNDS, such as \(arr[10]\) for an array of length 10 (valid indices 0-9)?

- **A)** The array automatically grows to accommodate the new index
- **B)** This causes a compile-time error, not a runtime error
- **C)** Java automatically returns \(0\) or \(null\) for the out-of-bounds access
- **D)** Java throws an \(ArrayIndexOutOfBoundsException\) at RUNTIME, crashing the program unless the exception is handled

Answer & Explanation:

**Answer: D)**

Out-of-bounds array access is a RUNTIME error (not caught by the compiler), since the compiler cannot always know what index value a variable will hold when the program actually runs.

Question #6 Active Recall

What is the value of \(arr[2]\) after \(int[]\ arr\ =\ \{10,\ 20,\ 30,\ 40\};\)?

- **A)** \(40\)
- **B)** \(30\)
- **C)** \(20\)
- **D)** \(2\)

Answer & Explanation:

**Answer: B)**

Using zero-based indexing, index 0 is 10, index 1 is 20, and index 2 is 30.

Question #7 Active Recall

What is the standard \(for\) loop pattern for visiting EVERY element of an array \(arr\) exactly once, in order?

- **A)** \(for\ (int\ i\ =\ arr.length;\ i\ >\ 0;\ i++)\ \{\ ...\ arr[i]\ ...\ \}\)
- **B)** \(for\ (int\ i\ =\ 0;\ i\

Answer & Explanation:

**Answer: B)**

This is THE standard array-traversal idiom: starting at index 0 and stopping strictly before \(arr.length\), correctly covering every valid index without going out of bounds.

Question #8 Active Recall

What is the ENHANCED FOR LOOP (also called a 'for-each' loop) syntax for traversing an array \(arr\) of \(int\) values?

- **A)** \(for\ (int\ value\ =\ arr)\ \{\ ...\ \}\)
- **B)** \(foreach\ (int\ value\ in\ arr)\ \{\ ...\ \}\)
- **C)** \(for\ (int\ value\ :\ arr)\ \{\ ...\ value\ ...\ \}\)
- **D)** \(for\ (arr\ :\ int\ value)\ \{\ ...\ \}\)

Answer & Explanation:

**Answer: C)**

The enhanced for-loop syntax uses a colon (\(:\)) to iterate over each element directly, without needing an explicit index variable.

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