Deck 9: Arrays

Question 1

Suppose that you have the following declaration. int[] alpha = new int[50]; int[][] beta = new int[10][5]; In this declaration, the array alpha has more components than the array beta.

Answer 1

False

Question 2

When a boolean array object is instantiated, its components are initialized to false.

Answer 2

True

Question 3

Given the declaration int[] list = new int[50]; the statement System.out.println(list[0] + "..." + list[49]); outputs all 50 components of the array list.

Answer 3

False

Question 4

Given the declaration double[] numList = new double[20]; the statement numList[12] = numList[5] + numList[7]; updates the content of the thirteenth component of the array numList.

Question 5

If a method has both a variable length formal parameter and other types of formal parameters, then the variable length formal parameter must be the first formal parameter of the formal parameter list.

Question 6

In row processing, a two-dimensional array is processed one row at a time.

Question 7

You can create an array of reference variables to manipulate objects.

Question 8

Only one-dimensional arrays can be passed as parameters.

Question 9

In a method call statement, when passing an array as an actual parameter, you use only its name.

Question 10

The statement int[] list = new int[15]; creates list to be an array of 14 components because array index starts at 0.

Question 11

Suppose list is a one-dimensional array, wherein each component is of the type int. The following for loop correctly finds the sum of the elements of list. int sum = 0; for (int num : list) sum = sum + num;

Question 12

Arrays have a fixed number of elements.

Question 13

The following statement creates alpha to be a two-dimensional array of 35 components. int[][] alpha = new int[20][15];

Question 14

Java stores two-dimensional arrays in a row order form in computer memory.

Question 15

When an array object is instantiated, its components are initialized to their default values.

Question 16

The array index can be any nonnegative integer less than the array size.

Question 17

A single array can hold components of many different data types.

Question 18

The base address of an array is the memory location of the first array component.

Question 19

In column processing, a two-dimensional array is processed one column at a time.

Question 20

If an array index is less than or equal to zero, an InvalidIndexException exception is thrown.

Question 21

Consider the following method definition. public static int strange(int[] list, int listSize, int item) {int count = 0; for (int j = 0; j < listSize; j++) if (list[j] == item) count++; return count;} Which of the following statements best describe the behavior of this method?

A) This method returns the number of values stored in list.
B) This method returns the sum of all the values of list.
C) This method returns the number of times item is stored in list.
D) This method can process an array of doubles.

Question 22

How many objects are present after the code fragment in the accompanying figure is executed?

A) 1
C) 7
B) 2
D) 14

Question 23

Only a fixed number of elements can be stored in a vector.

Question 24

Which of the following declares an array of int named beta?

A) int beta;
C) new int beta[];
B) int[] beta;
D) int beta = int[];

Question 25

What is the output of the following Java code? int[] list = {0, 5, 10, 15, 20}; for (int j = 0; j < 5; j++) System.out.print(list[j] + " "); System.out.println();

A) 0 1 2 3 4
C) 0, 5, 10, 15, 20
B) 0 5 10 15 20
D) 0 5 10 15

Question 26

How many rows are in the array seen in the accompanying figure?

A) 0
C) 10
B) 5
D) 15

Question 27

The method size in the class Vector returns the number of elements in the vector.

Question 28

What is stored in alpha after the following code executes? int[] alpha = new int[5]; for (int j = 0; j < 5; j++) {alpha[j] = 2 * j; if (j % 2 == 1) alpha[j - 1] = alpha[j] + j;}

A) alpha = {0, 2, 4, 6, 8}
C) alpha = {0, 3, 4, 7, 8}
B) alpha = {3, 2, 9, 6, 8}
D) alpha = {0, 2, 9, 6, 8}

Question 29

Which indices are in bounds for the array list, given the declaration in the accompanying figure?

A) 0, 1, 2, 3
C) 1, 3, 5, 7
B) 1, 2, 3, 4
D) 0, 1, 3, 5

Question 30

Which of the following is the array subscripting operator in Java?

A) .
C) new
B) {}
D) []

Question 31

Suppose you have the following declaration. double[] salesData = new double[500]; Which of the following range is valid for the index of the array salesData. (i) 0 through 500 (ii) 0 through 499

A) Only (i)
C) Both are invalid
B) Only (ii)
D) None of these

Question 32

How many components are in the array numList seen in the accompanying figure?

A) 0
C) 49
B) 30
D) 50

Question 33

Vectors can be used to implement lists.

Question 34

What is the value of alpha[4] after the following code executes? int[] alpha = new int[5]; for (int j = 0; j < 5; j++) alpha[j] = 2 * j - 1;

A) one
C) five
B) three
D) seven

Question 35

Given the following method heading public static void mystery(int list[], int size) and the declaration int[] alpha = new int[75]; Which of the following is a valid call to the method mystery?

A) mystery(alpha[75], 50);
C) mystery(alpha, 40);
B) mystery(alpha[], 50);
D) mystery(int[75], alpha)

Question 36

A Vector object can shrink during program execution.

Question 37

Given the method heading public static void strange(int a, int b) and the declaration int[] alpha = new int[20]; int[] beta = new int[25]; Which of the following is a valid call to the method strange?

A) strange(alpha[10], alpha[15]);
B) strange(alpha[5], beta);
C) strange(alpha[0], beta[25]);
D) strange(alpha, beta[20]);

Question 38

How many dimensions are in the array seen in the accompanying figure?

A) 1
C) 5
B) 2
D) 10

Question 39

The statement dataType[][][] arrayName; would declare a two-dimensional array.

Question 40

What is the index number of the last component in the array numList seen in the accompanying figure?

A) 0
C) 49
B) 30
D) 50

Question 41

What does the following statement do? Vector thisVector = new Vector();

A) It creates an empty vector to create a vector of Double objects.
B) It creates a vector with 10 elements to create a vector of Double objects.
C) This statement does not do anything.
D) It creates an array of Double objects.

Question 42

In which package is the class Vector located?

A) java.io
C) java.util
B) java.lang
D) java.text

Question 43

Suppose that sales is a two-dimensional array of 10 rows and 7 columns wherein each component is of the type int. Which of the following correctly finds the sum of the elements of the fifth row of sales?

A) int sum = 0;
B) int sum = 0;
C) int sum = 0;
D) int sum = 0;

Question 44

Which method of the class vector would you use to remove an element at a specific location?

A) removeAllElements
C) removeElementAt
B) removeElement
D) removeLocation

Question 45

How many columns are in the array seen in the accompanying figure?

A) 0
C) 10
B) 5
D) 15

Question 46

What is the value of table[2].length?

A) 0
C) 10
B) 5
D) 15

Question 47

What is the value of table.length?

A) 0
C) 10
B) 5
D) 15

Question 48

Which limitation of arrays does a vector overcome?

A) Arrays cannot increase in size; vectors can.
B) Arrays cannot be passed as parameters to methods; vectors can.
C) Arrays cannot be searched; vectors can.
D) There is a method that returns the length of a vector; there is no way to find the length of an array.

Question 49

Which method would you most likely use to add an element to an end of a vector?

A) insertElementAt
C) copyInto
B) addElement
D) lastElement

Question 50

Which method would you most likely use to find the location of an element in the vector?

A) lastElement
C) indexOf
B) elementAt
D) size