AP CSA Arrays and ArrayLists

Question 1

What is the index of the first element in a Java array?

Accepted Answer

0

Answer

Java arrays are zero-indexed, so the first element is always at index 0.

Question 2

Which method adds an element to the end of an ArrayList?

Accepted Answer

add()

Answer

The ArrayList method add(element) appends the specified element to the end of the list.

Question 3

What is the length of an array declared as `int[] arr = new int[5];`?

Accepted Answer

5

Answer

The integer passed to `new int[5]` specifies the array length as 5 elements (indices 0–4).

Question 4

Which of the following correctly accesses the last element of an array `arr` of length n?

Accepted Answer

arr[n-1]

Answer

Since arrays are zero-indexed, the last element is at index n-1 where n is the array's length.

Question 5

What does `ArrayList list = new ArrayList<>();` create?

Accepted Answer

An empty ArrayList that holds Integer objects

Answer

This statement creates an empty generic ArrayList that can store Integer wrapper objects.

AP CSA - Advanced Placement Computer Science A Practice Test