AP CSA Arrays and ArrayLists 3

Question 1

What happens if you try to store a double value in an int array in Java?

Accepted Answer

Compile-time error

Answer

Java is strongly typed; storing a double in an int array causes a compile-time type mismatch error.

Question 2

How do you get the number of rows in a 2D array called `matrix`?

Accepted Answer

matrix.length

Answer

For a 2D array, `matrix.length` gives the number of rows (outer array length).

Question 3

Which ArrayList method removes the first occurrence of a specified object?

Accepted Answer

remove(Object o)

Answer

ArrayList.remove(Object o) removes the first occurrence of the specified element from the list.

Question 4

What is traversing a 2D array row by row called?

Accepted Answer

Row-major order traversal

Answer

Iterating through a 2D array row by row (outer loop over rows) is called row-major order traversal.

Question 5

What is the default value of elements in a newly created `int[]` array?

Accepted Answer

0

Answer

Java initializes all elements of a numeric array to 0 by default when created with `new`.

AP CSA - Advanced Placement Computer Science A Practice Test