Arrays - Quiz

Access the last element of the scores array using its length

Quickly create an int array with three default-initialized elements

Fill the monthlySales array with zeros in a single statement

Which declaration correctly creates an array that can hold 10 double temperature readings?

What happens if you access numbers[5] in an int[] numbers = new int[5]; array?

Which operation is a typical use case for a linear search on an array?

For binary search on an int[] using your own implementation, what must be true?

How do you access the number of rows in a 2D int[][] matrix?

In a jagged int[][] arr, what does arr[1].length represent?

Which Arrays class method converts an int[] to a readable String?

Which method would you use to copy only the first 3 elements of an int[] source into a new int[]?

What is a key advantage of System.arraycopy over manual copying in a loop?

Which statement about Arrays.equals(int[], int[]) is correct?

Why might you create a copy of an int[] before sorting it?

Order the steps to search for a username in a sorted String[] using binary search you implement yourself.

Drag and drop to reorder, or use the arrows.

Order the steps to create and use a 2D int array for a game board.

Drag and drop to reorder, or use the arrows.

What is the output of this code?

1int[] scores = {10, 20, 30, 40};
2int index = 1;
3int result = scores[index] + scores[index + 2];
4System.out.println(result);

What is the output of this code?

1int[][] grid = {
2    {1, 2},
3    {3, 4}
4};
5int value = grid[0][1] * grid[1][0];
6System.out.println(value);

What is the output of this code?

1int[] data = {5, 3, 9, 1};
2java.util.Arrays.sort(data);
3System.out.println(data[0] + ":" + data[data.length - 1]);

What is the output of this code?

1int[] original = {2, 4, 6};
2int[] copy = java.util.Arrays.copyOf(original, 2);
3copy[0] = 10;
4System.out.println(original[0] + "," + copy[0]);

What is the output of this code?

1int[] a = {1, 2, 3};
2int[] b = a;
3b[1] = 99;
4System.out.println(a[0] + a[1] + a[2]);

Find the bug in this code that initializes and prints a 2D array of seats.

Click on the line(s) that contain the bug.

public class Theater {

    public static void main(String[] args) {

        int[][] seats = new int[3][];

        for (int row = 0; row < seats.length; row++) {

            for (int col = 0; col < seats[row].length; col++) {

                seats[row][col] = row + col;

            }

        }

        System.out.println(seats[0][0]);

    }

}

Find the bug in this code that copies sales data into a larger array.

Click on the line(s) that contain the bug.

public class SalesCopy {

    public static void main(String[] args) {

        int[] monthly = {10, 20, 30};

        int[] yearly = new int[12];

        System.arraycopy(yearly, 0, monthly, 0, monthly.length);

        System.out.println(java.util.Arrays.toString(yearly));

    }

}

Match each Arrays class method with its primary purpose.

Click an item on the left, then click its match on the right. Click a matched item to unmatch.

Match the array-related concept with its best description.

Click an item on the left, then click its match on the right. Click a matched item to unmatch.

Complete the code to create a copy of an int array and sort the copy without changing the original.

Complete the code to create and use a 2D int array for storing pixel brightness values.

Complete the code to perform a linear search on an int array for a target value.

Complete the code to copy part of an int array using System.arraycopy.

Click the line that will cause an ArrayIndexOutOfBoundsException at runtime.

Click on the line to select.

int[] values = new int[3];

values[0] = 10;

values[2] = 30;

int x = values[3];

System.out.println(x);

Click the line that will throw a NullPointerException when executed.

Click on the line to select.

int[][] data = new int[2][];

data[0] = new int[3];

int sum = data[1][0];

System.out.println(sum);