Deck 9: Multidimensional Arrays and the Arraylist Class

Question 1

In an array of floats, each element contains a float value. What is true about the array?

A) Each element contains a double value.
B) The array is declared with a primitive type element.
C) The array requires three sets of empty brackets.
D) Float points to the location of the class.

Answer 1

B

Question 2

The ArrayList class uses generics, which are:

A) parameterized types, meaning that the data type will be defined at the time a client class declares and instantiates an object of the class.
B) parameterized types, meaning that programmers must specify the class of the objects they use.
C) initialized types, meaning that programmers can design a code class without specifying the class of the objects they use.
D) None of these is correct.

Answer 2

A

Question 3

Why can you not print the contents of an array using only the array name?

A) Java does not support aggregate operations on multidimensional arrays.
B) Java does not support aggregate operations on single-dimensional arrays.
C) Each element in an array must be processed individually.
D) All of these are correct.

Answer 3

D

Question 4

Jessica wants to design a search engine for an online dictionary of software-related terms. Which class should she use?

A) Array class
B) Auto class
C) ArrayList class
D) Assign class

Question 5

In the following method, what type of object is returned (the answer has been omitted on purpose)?
Set( int index, E element )

A) It returns a boolean value.
B) It returns void.
C) It returns int.
D) It returns the data type of the ArrayList.

Question 6

The syntax for declaring a multidimensional array requires the brackets to follow the array name.

Question 7

The general pattern for processing the elements of column j of a two-dimensional array called arrayName uses a single for loop.

Question 8

The enhanced for loop enables looping through the ArrayList objects automatically.

Question 9

Multidimensional arrays are useful for which of the following?

A) You want to organize data along several dimensions.
B) You want to assign values after instantiating a list.
C) There is not a lot of data to store in memory.
D) None of these is correct.

Question 10

_____________ arrays allow us to represent data organized along n dimensions with a single array.

A) Floating
B) Dual
C) Multidimensional
D) None of these is correct.

Question 11

Why would you want to insert a comma between two array names in one statement?

A) It allows you to instantiate multiple multidimensional arrays of the same data type.
B) It allows you to declare multiple multidimensional arrays of different data types.
C) It allows you to declare multiple multidimensional arrays of the same data type.
D) It allows you to instantiate single arrays of the same data type.

Question 12

Which of the following are errors in this syntax declaring a two-dimensional array?
Datatype [4] [0] [3] arrayName:

A) The brackets must be empty.
B) There must be two brackets, not three.
C) The syntax must end in a semicolon, not a colon.
D) All of these are errors in the syntax.

Question 13

The syntax for instantiating a two-dimensional array, where rows are numberOfMonths, columns are numberOfStudents, the array name is starStudent, and the data type is double, can look something like this:
starStudent = new double [numberOfMonths][numberOfStudents];

Question 14

When a multidimensional array is instantiated, elements of arrays with numeric types are initialized to null.

Question 15

Why is it a good idea to check that the current column number is less than arrayName[i].length before attempting to access arrayName[i][j]?

A) Rows might have a different number of columns.
B) Accessing columns that do not exist will result in ArrayIndexOutofBoundsException at run time.
C) The column number must be within the range of 0 to arrayName[i].length - 1.
D) All of these are correct.

Question 16

In the outer for loop, using the condition i <= arrayName.length will result in:

A) a compiler error.
B) ArrayIndexOutOfBoundsException.
C) ArrayInBoundsException.
D) None of these is correct.

Question 17

After each completion of the inner loop when processing a row of a two-dimensional array, what must be done?

A) Initialize the processing variables for the current row.
B) Finish processing the current row.
C) Calculate the minimum value.
D) All of these are correct.

Question 18

This code would generate compiler errors.
for ( int i = 0; i < arrayName.length; i++ )
{
for ( int j = 0; j < arrayName[i].length; j++ )
{
// process element arrayName[i][j]
}
}

Question 19

To process elements of a three-dimensional array, use a double for loop.

Question 20

Programmers can reuse code from the ArrayList class.

Question 21

Use add( E element ) in the ArrayList class to update a list of slang terms with additional terms.

Question 22

How many empty sets of brackets are needed to declare an array?

A) One
B) Two
C) At least two sets are needed
D) It depends on how many dimensions are involved

Question 23

Initiating a two-dimensional array and then instantiating each row as a single-dimensional array will accomplish which of the following?

A) An array may have a different number of rows for each column.
B) An array may have a different number of columns for each row.
C) An array will have the same number of rows and columns.
D) There is not enough information to draw a conclusion.

Question 24

What is the purpose of this code?
For ( int i = 0; i < arrayName.length; i++ )
{
For ( int j = 0; j < arrayName[i].length; j++ )
{
// process element arrayName[i][j]
}
}

A) It is the general pattern for processing the elements of a two-dimensional array called arrayName in row-first, column-second order.
B) It is the general pattern for processing the elements of a single-dimensional array called arrayName in row-first, column-second order.
C) It is the general pattern for processing the elements of a two-dimensional array called arrayName in column-first, row-second order.
D) There is not enough information to draw a conclusion.

Question 25

What is the name of the method that returns the number of elements in an ArrayList object?

A) size
B) number
C) length

Question 26

In the header for ( Auto current : autos ):

A) Auto is an ArrayList.
B) current is an ArrayList.
C) autos is an ArrayList.

Question 27

In the header for ( Auto current : autos ):

A) Auto represents the Auto object that will be processed inside the loop body.
B) current represents the Auto object that will be processed inside the loop body.
C) autos represents the Auto object that will be processed inside the loop body.

Question 28

An ArrayList is not expandable.

Question 29

Three-dimensional arrays are not allowed in Java.

Question 30

We can store primitive data types in an ArrayList object.

Question 31

The ArrayList class uses generics.

Question 32

The name of the method that enables us to delete an element at a specified index in an ArrayList is __________.

Question 33

The __________ enables looping through an ArrayList object without using a counter and without using the get method to access each object.

Question 34

To access the element at row i and column j of a two-dimensional array named grades, we would use which of the following?

A) grades
B) grades[ i ][ j ]
C) grades[ j ][ i ]
D) grades( i )( j )
E) grades( j )( i )

Question 35

To access the number of rows in a two-dimensional array named grades, we would use which of the following?

A) grades
B) grades.size( )
C) grades.size
D) grades.length( )
E) grades.length

Question 36

To access the number of columns in row i of a two-dimensional array named grades, we would use which of the following?:

A) grades.length
B) grades[ i ].length
C) grades( i ).length
D) grades( i ).size
E) grades{ i }.length

Question 37

When processing all the elements of row i of a two-dimensional array named grades using a for loop with variable j, what is the condition of the for loop?

A) j < length
B) j < grades.length
C) j <= grades.length
D) j < grades[i].length
E) j <= grades[i].length

Question 38

The ArrayList class belongs to which package?

A) java.lang
B) java.text
C) java.util
D) java.list
E) java.array

Question 39

How do you declare an ArrayList object reference of Book objects named books?

A) ArrayList< > books;
B) ArrayList books;
C) ArrayList books;
D) ArrayList books;
E) ArrayList Book;

Question 40

An ArrayList object reference of Book objects named books has already been declared. How do you instantiate it using the ArrayList default constructor?

A) books = new ArrayList( );
B) books = new ArrayList( );
C) books = new ArrayList( );
D) books = new Book( );
E) books = new Book( );

Question 41

When declaring a two-dimensional array, we use two sets of square brackets.

Question 42

We can instantiate a two-dimensional array by assigning values when the array is declared.

Question 43

In a two-dimensional array, the number of elements in each row must be the same for every row.

Question 44

We cannot combine the declaration and instantiation of a multidimensional array.

Question 45

To process all the elements of a two-dimensional array, we use a double loop.

Question 46

We can pass a two-dimensional array parameter to a method.

Question 47

A method cannot return a two-dimensional array parameter.

Question 48

A two-dimensional array is an array of __________.

Question 49

When processing the elements of a two-dimensional array one row at a time, we should __________ the row processing variables before processing each row.

Question 50

An ArrayList automatically __________ its capacity as needed.

Question 51

If we want to store primitive data types in an ArrayList object, then we should use __________ classes.

Question 52

The ArrayList class uses generics; thus, the data type used is defined at a time the __________ class declares and instantiates an ArrayList object.

Question 53

The name of the method that enables us to append an element to the end of an ArrayList is __________.

Question 54

Identify how to instantiate a two-dimensional array by assigning initial values when the array is declared.

Question 55

Compare the function of the following two statements:
arrayName.length
arrayName[i].length

Question 56

When processing all the elements of a column of a two-dimensional array, what possible runtime error do we have to worry about?

Question 57

Simeon wants to keep track of his batting average for each day of each week of the next baseball season. Evaluate what is wrong with this code and recommend an alternative code.
double [ ] battingAverage;

Question 58

Which keyword would you add to this code to instantiate the array, allocating memory for the array? Provide the updated code.
arrayName = datatype [exp1][exp2];

Question 59

Theorize why the following code would generate compiler errors:
Auto [4][12] cars;

Question 60

Theorize why the following code would generate compiler errors:
int [ ][ ] highTemps = new int [2][3];
highTemps = { { 89, 85, 98 },
{ 88, 90, 92 } };

Question 61

A code written to analyze the average high temperatures in four cities for June, July, and August was set up so that the cities are the rows. Evaluate the results of this code:
avgHighTemps[2][0] = 75.2; // row 2
avgHighTemps[2][1] = 82.3;
avgHighTemps[2][2] = 78.5;
avgHighTemps[2][3] = 71.6;

Question 62

Compare lines 22-23 with 27-28 and explain how the results will differ.
21 System.out.println( "\nUsing the enhanced for loop:" );
22 for ( Integer currentInteger : list )
23 System.out.print( currentInteger + "\t" );
24 System.out.println( );
25
26 System.out.println( "\nUsing unboxing and enhanced for loop:" );
27 for ( int currentInt : list ) // unboxing
28 System.out.print( currentInt + "\t" );
29 System.out.println( );