Deck 7: Arrays and Arraylists

Question 1

A programmer must do the following before using an array:

A) declare then reference the array.
B) create then declare the array.
C) create then reference the array.
D) declare then create the array.

Answer 1

declare then create the array.

Question 2

An exception object's ________ method returns the exception's error message.

A) String
B) Message
C) Error
D) toString

Answer 2

toString

Question 3

Which of the following statements is false?

A) An exception indicates a problem that occurs while a program executes.
B) Exception handling enables you to create fault-tolerant programs that can resolve (or handle) exceptions-in many cases, this allows a program to continue executing as if no problems were encountered.
C) The catch block contains the code that might throw an exception, and the try block contains the code that handles the exception if one occurs.
D) Inside the catch block, you can use the parameter's identifier to interact with a caught exception object.

Answer 3

C

Question 4

Consider the array:
s[0] = 7
S[1] = 0
S[2] = -12
S[3] = 9
S[4] = 10
S[5] = 3
S[6] = 6
The value of s[s[6] - s[5]] is:

A) 0.
B) 3.
C) 9.
D) 10.

Question 5

Invalid possibilities for array indices include .

A) Positive integers.
B) Negative integers.
C) Zero.
D) None of the above.

Question 6

Exception handling helps you create ________ programs.

A) high-performance
B) logic-error-free
C) fault-tolerant
D) compilation-error-free

Question 7

Which of the following statements is true?

A) The catch block contains the code that might throw an exception.
B) The try block contains the code that handles the exception if one occurs.
C) You can have many catch blocks to handle different types of exceptions.
D) When a try block terminates, any variables declared in the try block are preserved.

Question 8

Which of the following statements about arrays are true? A. An array is a group of variables containing values that all have the same type.
B) Elements are located by index.
C) The length of an array c is determined by the expression

A) A, C, D.
B) A, B, D.
C) C, D.
C)length();. D. The zeroth element of array c is specified by c[0].
D) A, B, C, D.

Question 9

Which of the following will not produce a compiler error?

A) Changing the value of a constant after it is initialized.
B) Changing the value at a given index of an array after it is created.
C) Using a final variable before it is initialized.
D) All of the above will produce compiler errors.

Question 10

Consider the code segment below. Which of the following statements is false? int[] g;
G = new int[23];

A) The value of g[3] is -1.
B) The first statement declares an array reference.
C) The second statement creates the array.
D) g is a reference to an array of integers.

Question 11

Constant variables also are called .

A) write-only variables
B) finals
C) named constants
D) All of the above

Question 12

What do the following statements do?
double[] array;
Array = new double[14];

A) Create a double array containing 13 elements.
B) Create a double array containing 14 elements.
C) Create a double array containing 15 elements.
D) Declare but do not create a double array.

Question 13

Consider integer array values, which contains 5 elements. Which statements successfully swap the contents of the array at index 3 and index 4?

A) values[3] = values[4];
Values[4] = values[3];
B) values[4] = values[3];
Values[3] = values[4];
C) int temp = values[3];
Values[3] = values[4];
Values[4] = temp;
D) int temp = values[3];
Values[3] = values[4];
Values[4] = values[3];

Question 14

Which of the following statements about creating arrays and initializing their elements is false?

A) The new keyword should be used to create an array.
B) When an array is created with operator new, the number of elements must be placed in square brackets following the type of element being stored.
C) The elements of an array of integers have a value of null before they are initialized.
D) A for loop is commonly used to set the values of the elements of an array.

Question 15

Arrays are ________.

A) variable-length entities
B) fixed-length entities
C) data structures that contain up to 10 related data items
D) used to draw a sequence of lines, or "rays"

Question 16

Attempting to access an array element outside of the bounds of an array, causes a(n) .

A) ArrayOutOfBoundsException.
B) ArrayElementOutOfBoundsException.
C) ArrayIndexOutOfBoundsException.
D) ArrayException.

Question 17

A(n)________ indicates a problem that occurs while a program executes.

A) syntax error
B) omitted import
C) missing semicolon
D) exception

Question 18

Which of the following initializer lists would correctly set the elements of array n?

A) int[] n = {1, 2, 3, 4, 5};.
B) array n[int] = {1, 2, 3, 4, 5};.
C) int n[5] = {1; 2; 3; 4; 5};.
D) int n = new int(1, 2, 3, 4, 5);.

Question 19

Which expression adds 1 to the element of array arrayName at index i?

A) ++arrayName[i].
B) arrayName++[i].
C) arrayName[i++].
D) None of the above.

Question 20

Which flag in a format specifier indicates that values with fewer digits than the field width should begin with a leading 0?

A) p.
B) l.
C) w.
D) 0.

Question 21

Assume class Book has been declared. Which set of statements creates an array of Books?

A) Book[] books;
Books = new Book[numberElements];
B) Book[] books];
Books = new Book()[numberElements];
C) new Book() books[];
Books = new Book[numberElements];
D) All of the above.

Question 22

In array items, which expression below accesses the value at row 3 and column 4?

A) items[3].[4]
B) items[3[4]]
C) items[3][4]
D) items[3, 4]

Question 23

Assume array items contains the integer values 0, 2, 4, 6 and 8. Which of the following uses the enhanced for loop to display each value in array items?

A) for (int i = 0; i < items.length; i++) {
System.out.prinf("%d%n", items[i]);
}
B) for (int i : items) {
System.out.prinf("%d%n", items[i]);
}
C) for (int i : items) {
System.out.prinf("%d%n", i);
}
D) for (int i = 0 : items.length) {
System.out.prinf("%d%n", items[i]);
}

Question 24

Which set of statements totals the values in two-dimensional int array items?

A) int total = 0;
For (int subItems : items) {
For (int item : subItems) {
Total += item;
}
}
B) int total = 0;
For (int item: int[] subItems : items) {
Total += item;
}
C) int total = 0;
For (int[] subItems : items) {
For (int item : items) {
Total += item;
}
}
D) int total = 0;
For (int[] subItems : items) {
For (int item : subItems) {
Total += item;
}
}

Question 25

When you pass an array or an individual array element of a reference type to a method, the called method receives ________. When you pass an individual element of a primitive type, the called method receives ________.

A) a copy of the element's reference, a copy of the element's reference
B) a copy of the element's value, a copy of the element's reference
C) a copy of the element's value, a copy of the element's value
D) a copy of the element's reference, a copy of the element's value

Question 26

Which of the following statements is false?

A) When an argument is passed by reference, the called method can access the argument's value in the caller directly but cannot modify it.
B) All arguments in Java are passed by value.
C) To pass an individual array element to a method, use the indexed name of the array.
D) To pass an object reference to a method, simply specify in the method call the name of the variable that refers to the object.

Question 27

The preferred way to traverse a two-dimensional array is to use .

A) a do while statement.
B) a for statement.
C) two nested for statements.
D) three nested for statements.

Question 28

An argument type followed by a(n) in a method's parameter list indicates that the method receives a variable number of arguments of that particular type.

A) square brackets ([])
B) ellipsis (...)
C) varargs keyword
D) All of the above are acceptable to indicate a variable number of arguments.

Question 29

Which set of statements totals the items in each row of two-dimensional array items, and displays each row's total?

A) for (int row = 0; row < items.length; row++) {
Int total = 0;
For (int column = 0; column < items[row].length; column++) {
Total += items[row][column];
System.out.printf("Row %d's total is %d%n", row, total);
}
B) int total = 0;
For (int row = 0; row < items.length; row++) {
For (int column = 0; column < items[row].length; column++) {
Total += items[row][column];
}
System.out.printf("Row %d's total is %d%n", row, total);
}
C) int total = 0;
For (int row = 0; row < items.length; row++) {
For (int column = 0; column < items[column].length; column++) {
Total += items[row][column];
}
System.out.printf("Row %d's total is %d%n", row, total);
}
D) for (int row = 0; row < items.length; row++) {
Int total = 0;
For (int column = 0; column < items[column].length; column++) {
Total += items[row][column];
}
System.out.printf("Row %d's total is %d%n", row, total);
}

Question 30

Consider array items, which contains the values 0, 2, 4, 6 and 8. If method changeArray is called with the method call changeArray(items, items[2]), what values are stored in items after the method has finished executing? public static void changeArray(int[] passedArray, int value) {
PassedArray[value] = 12;
Value = 5;
}

A) 0, 2, 5, 6, 12.
B) 0, 2, 12, 6, 8.
C) 0, 2, 4, 6, 5.
D) 0, 2, 4, 6, 12.

Question 31

Which of the following tasks cannot be performed using an enhanced for loop?

A) Calculating the product of all the values in an array.
B) Displaying all even element values in an array.
C) Comparing the elements in an array to a specific value.
D) Incrementing the value stored in each element of the array.

Question 32

An array with m rows and n columns is not ________.
A. an m-by-n array.
B. an n-by-m array.
C. a two-dimensional array.
D. a dual-transcripted array.

A) A and C.
B) A and D.
C) B and D.
D) B and C.

Question 33

Which statement correctly passes the array items to method takeArray? Array items contains 10 elements.

A) takeArray(items[]).
B) takeArray(items).
C) takeArray(items[9]).
D) Arrays cannot be passed to methods-each item must be sent to the method separately.

Question 34

Which of the following sets of statements creates a multidimensional array with 3 rows, where the first row contains 1 value, the second row contains 4 items and the final row contains 2 items?

A) int[][] items;
Items = new int[3][?];
Items[0] = new int[1];
Items[1] = new int[4];
Items[2] = new int[2];
B) int[][] items;
Items = new int[3][];
Items[0] = new int[1];
Items[1] = new int[4];
Items[2] = new int[2];
C) int[][] items;
Items = new int[?][?];
Items[0] = new int[1];
Items[1] = new int[4];
Items[2] = new int[2];
D) int[][] items;
Items[0] = new int[1];
Items[1] = new int[4];
Items[2] = new int[2];

Question 35

In Java, multidimensional arrays ________.

A) are not directly supported.
B) are implemented as arrays of arrays.
C) are often used to represent tables of values.
D) All of the above.

Question 36

For tthe array that was the correct answer in the previous question, what is the value returned by items[1][0]?

A) 4.
B) 8.
C) 12.
D) 6.

Question 37

What kind of application tests a class by creating an object of that class and calling the class's methods?

A) Pseudo application.
B) Debugger.
C) Declarator.
D) Test harness.

Question 38

Which of the following statements creates a multidimensional array with 3 rows, where the first row contains 1 element, the second row contains 4 elements and the final row contains 2 elements?

A) int[][] items = {{1, null, null, null}, {2, 3, 4, 5}, {6, 7, null, null}};
B) int[][] items = {{1}, {2, 3, 4, 5}, {6, 7}};
C) int[][] items = {{1}, {2, 3, 4, 5}, {6, 7}, {});
D) int[][] items = {{1}, {4}, {2}};

Question 39

How many Book objects are created by the following statement? Book[] books = new Book[10];

A) 10
B) 0
C) 5
D) None of the above.

Question 40

Which statement below initializes array items to contain 3 rows and 2 columns?

A) int[][] items = {{2, 4}, {6, 8}, {10, 12}};
B) int[][] items = {{2, 6, 10}, {4, 8, 12}};
C) int[][] items = {2, 4}, {6, 8}, {10, 12};
D) int[][] items = {2, 6, 10}, {4, 8, 12};

Question 41

Which method call converts the value in variable stringVariable to an integer?

A) Convert.toInt(stringVariable)
B) Convert.parseInt(stringVariable)
C) Integer.parseInt(stringVariable)
D) Integer.toInt(stringVariable)

Question 42

Which command below runs TestProgram, and passes in the values files.txt and 3?

A) java TestProgram files.txt 3.
B) java TestProgram files.txt, 3.
C) java TestProgram "files.txt", "3".
D) None of the above.

Question 43

Class Arrays methods sort, binarySearch, equals and fill are overloaded for primitive-type arrays and Object arrays. In addition, methods __________ and __________ are overloaded with generic versions.

A) sort, binarySearch.
B) sort, fill.
C) binarySearch, equals.
D) binarySearch, fill.

Question 44

Class ________ represents a dynamically resizable array-like data structure.

A) Array
B) ArrayList
C) Arrays
D) None of the above.

Question 45

Which of the following is false?

A) The size of an ArrayList can be determined via its length instance variable.
B) The size of an ArrayList can be determined via its size method.
C) You can add a new item to the end of an ArrayList with its add method.
C) You can get an item from a specified index in an ArrayList with its get method.

Question 46

Class Arrays provides method __________ for comparing arrays to determine whether they have the same contents.

A) compare
B) compares
C) equal
D) equals