Deck 7: Arrays and Array Lists

Question 1

What is the result of executing this code snippet?

A)The code snippet does not give any output.
B)The code snippet displays all the marks stored in the array without any redundancy.
C)The code snippet causes a bounds error.
D)The code snippet executes an infinite loop.

Answer 1

The code snippet causes a bounds error.

Question 2

Which statements about the enhanced for loop are true for arrays of primitive data?
I.It is suitable for all array algorithms.
II.It does not allow the contents of the array to be modified.
III.It does not require the use of an index variable.

A)I, II only
B)I, III only
C)II, III only
D)I, II, III

Answer 2

II, III only

Question 3

Identify the correct statement for defining an integer array named numarray of ten elements.

A)int[] numarray = new int[9];
B)int[] numarray = new int[10];
C)int[10] numarray;
D)int numarray[10];

Answer 3

int[] numarray = new int[10];

Question 4

In a partially filled array, the number of slots in the array that are not currently used is the

A)length of the array minus the number of elements currently in the array.
B)number of elements currently in the array minus the length of the array.
C)length of the array plus the number of elements currently in the array.
D)number of elements currently in the array.

Question 5

Which one of the following statements is correct for the given code snippet?

A)Line 2 declares and initializes an array of three elements with value 5.
B)Line 2 causes a bounds error because 3 is an invalid index number.
C)Line 2 initializes the third element of the array with value 5.
D)Line 2 initializes all the elements of the array with value 5.

Question 6

If currLength is an integer variable that gives the number of elements currently in the array myArray, which code snippet prints out the elements in the partially filled array of integers?

A)
B)
C)
D)

Question 7

When a Java program terminates and reports an exception, the error message contains which pieces of useful information?
I.the compile and revision control history of the source code changes that caused the error
II.the name of the exception that occurred
III.the stack trace

A)I, II only
B)I, III only
C)II, III only
D)I, II, III

Question 8

The enhanced for loop is

A)convenient for traversing all elements in an array.
B)convenient for traversing elements in a partially filled array.
C)only used for arrays of integers.
D)used to initialize all array elements to a common value.

Question 9

What is the result of the following code?

A)The elements of the array values are initialized to zero.
B)The elements of the array element are initialized to zero.
C)The first element of the array values is initialized to zero.
D)The array values is not modified.

Question 10

Consider the following line of code:
int[] somearray = new int[30];
Which one of the following options is a valid line of code for displaying the twenty-eighth element of somearray?

A)System.out.println(somearray[28]);
B)System.out.println(somearray(28));
C)System.out.println(somearray(27));
D)System.out.println(somearray[27]);

Question 11

When an array myArray is only partially filled, how can the programmer keep track of the current number of elements?

A)access myArray.length()
B)maintain a companion variable that stores the current number of elements
C)access myArray.currentElements()
D)access myArray.length() - 1

Question 12

Which one of the following statements is true about using arrays with methods?

A)Arrays can be method arguments, and return values, just like any other values.
B)A method can only accept arguments that are elements of an array, but not the whole array.
C)A method may accept an argument that is an array, but it cannot return a result that is an array.
D)If a method is defined to have an array as a method argument, it must also define the size of the array as another method argument.

Question 13

Which one of the following statements is correct about the given code snippet?

A)The for loop initializes all the elements of the array.
B)The for loop initializes all the elements except the first element.
C)The for loop initializes all the elements except the last element.
D)The for loop initializes all the elements except the first and last elements.

Question 14

What is the output of the given code snippet?

A)2345
B)1234
C)1345
D)1111

Question 15

What is the valid range of index values for an array of size 10?

A)0 to 9
B)0 to 10
C)1 to 9
D)1 to 10

Question 16

What is the output of the following code snippet?

A)1050
B)2030
C)3040
D)4050

Question 17

What is displayed after executing the given code snippet?

A)The code snippet displays the total marks of all ten subjects.
B)The for loop causes a run-time time error on the first iteration.
C)The code snippet causes a bounds error.
D)The code snippet displays zero.

Question 18

Complete the following code snippet with the correct enhanced for loop so it iterates over the array without using an index variable.

A)for (String str : arr)
B)for (str : String arr)
C)for (str[] : arr)
D)for (arr[] : str)

Question 19

Which one of the following statements is a valid initialization of an array named somearray of ten elements?

A)int[] somearray = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
B)int somearray[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
C)int[10] somearray = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
D)int somearray[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

Question 20

Which statement correctly describes the enhanced for loop?

A)In the enhanced for loop, the element variable is assigned.In the basic for loop, the index variable is assigned.
B)In the enhanced for loop, the index variable is assigned.In the basic for loop, the element variable is assigned.
C)The enhanced for loop has a very specific purpose: modifying the contents of the array.
D)The enhanced for loop has a very specific purpose: initializing the contents of the array.

Question 21

Consider the following code snippet in Java 6 or later: What does the last element of data2 contain?

A)"abc"
B)"def"
C)"ghi"
D)"jkl"

Question 22

Assume the array of integers values has been created.Which condition must be used in the indicated area so the loop below will assign max the largest value in values?

A)max > val
B)val > max
C)values[val] > max
D)max > values[val]

Question 23

Consider the following code snippet:
String[] data = { "123", "ghi", "jkl", "def", "%&*" };
Which statement sorts the data array in ascending order?

A)data = Arrays.sort();
B)Arrays.sort(data);
C)data = Arrays.sort(data.length);
D)data = Arrays.sort(data);

Question 24

What is the output of the following code snippet?

A)24 0 30 16
B)24 0 30 6
C)24 7 30 16
D)24 16 24 16

Question 25

Assume the following variable has been declared and given a value as shown:
int[] numbers = {9, 17, -4, 21 };
Which is the value of numbers.length?

A)3
B)4
C)9
D)21

Question 26

Consider the following code snippet:
String[] data = { "abc", "def", "ghi", "jkl" };
Using Java 6 or later, which statement grows the data array to twice its size?

A)data = Arrays.copyOf(data, 2 * data.length);
B)data = Arrays.copyOf(data, 2);
C)data = Arrays.copyOf(data, 2 * data);
D)data = Arrays.copyOf(data, 2 * data.size());

Question 27

When an array reading and storing input runs out of space

A)the program could be recompiled with a bigger size for the array.
B)the array could be "grown" using the growArray method.
C)it automatically resizes to accommodate new elements.
D)the array could be "grown" using the new command and the copyOf method.

Question 28

Which code snippet calculates the sum of all the elements in even positions in an array?

A)
B)
C)
D)

Question 29

What (if anything) is wrong with the following code snippet, which searches for the searchedValue variable in the array data?

A)There is nothing wrong.
B)There is a compile-time error.
C)There is a bounds error.
D)There is a logic error.

Question 30

What is the output of the following code snippet?

A)86 2 24 4
B)86 24 3 4
C)1 86 24 4
D)1 2 24 86

Question 31

Suppose you wish to write a method that returns the sum of the elements in partially filled array.Which is the best choice for a method header?

A)public int sum(int[] values)
B)public int sum()
C)public int sum(int[] values, int currSize)
D)public int sum(int[] values, int size, int currSize)

Question 32

It may be necessary to "grow" an array when reading inputs because

A)the number of inputs may not be known in advance.
B)arrays in Java must be resized after every 100 elements.
C)arrays are based on powers of two.
D)the only alternative is a bounds exception.

Question 33

Which code snippet calculates the sum of all the even elements in an array values?

A)
B)
C)
D)

Question 34

Select the statement that reveals the logic error in the following method.

A)double m = minimum(new double[] { 1.2, -3.5, 6.6, 2.4 });
B)double m = minimum(new double[] { 1.2, 23.5, 16.6, -23.4 });
C)double m = minimum(new double[] { -10.2, 3.5, 62.6, 21.4 });
D)double m = minimum(new double[] { 12.2, 31.5, 6.6, 2.4 });

Question 35

When the order of the elements is unimportant, what is the most efficient way to remove an element from an array?

A)Delete the element and move each element after that one to a lower index.
B)Replace the element to be deleted with the last element in the array.
C)Replace the element to be deleted with the first element in the array.
D)Replace the element with the next element.

Question 36

Consider the following code snippet: In Java 6 and later, which statement copies the data array to the data2 array?

A)data2 = Arrays.copyOf(data, data2.length);
B)data2 = Arrays.copyOf(data, data.length);
C)data2 = Arrays.copyOf(data, data.size());
D)data2 = Arrays.copyOf(data);

Question 37

Assume the array of integers values has been created.Which condition must be used in the indicated area so the loop below will assign max the largest value in values?

A)current > max
B)max > current
C)max > values[current]
D)values[current] > max

Question 38

Assume the array of integers values has been created and process is a method that has a single integer parameter.Which of the following is equivalent to the loop below?

A)
B)
C)
D)

Question 39

Assume the variable numbers has been declared to be an array that has at least one element.Which is the following represents the last element in numbers?

A)numbers[numbers.length]
B)numbers.length
C)numbers[-1]
D)numbers[numbers.length - 1]

Question 40

Consider the following code snippet.Which statement should be used to fill in the empty line so that the output will be [32, 54, 67.5, 29, 35]?

A)String str = Arrays.format(data);
B)String str = data.toString();
C)String str = Arrays.toString(data);
D)String str = str + ", " + data[i];

Question 41

Assume the method doSomething has been defined as follows: What does the method do?

A)It copies the integer array values to a new array.
B)It swaps the integer values stored in positions p1 and p2 of the array values.
C)It moves each element of the array values to a higher index position.
D)It inserts a new value into the array values.

Question 42

Consider the code snippet below: When the loop finishes what does the value of the boolean variable found indicate?

A)the size of the array values
B)whether or not the value 42 was found in the array
C)whether or not the value 0 was found in the array
D)the position where the value 42 is located in the array

Question 43

Suppose you wish to process an array of values and eliminate any potential duplicate values stored in the array.Which array algorithms might be adapted for this?

A)find the minimum
B)remove an element
C)add an element
D)calculate the sum of the elements

Question 44

The method findLargest should return the largest of any number of double values.For example, the call findLargest (3.4, -2.6, 2.9) should return 3.4 and the call findLargest (9.2, 17.6, 3.4, -2.6, 2.9) should return 17.6.Partial code to do this is given below:


What code will complete this method?

A)
B)
C)
D)

Question 45

Assume the method createSomething has been defined as follows:

A)[3, 4, 5, 6]
B)[4, 4, 4]
C)[3, 3, 3, 3]
D)[4, 5, 6]

Question 46

What will be printed by the statements below?

A)0
B)1
C)2
D)3

Question 47

What will be printed by the statements below?

A)7 5 6 4
B)7 6 5 4
C)7 5 6 7
D)4 5 6 4

Question 48

The integer array numbers will be filled with values from the Scanner object in.If there are more input values than there are spaces in the array, only enough values to fill the array should be read.The integer variable currentSize should be set to the number of values read.Partial code to do this is given below: What condition will complete this code?

A)currentSize < numbers.length && in.hasNextInt()
B)currentSize < numbers.length || in.hasNextInt()
C)currentSize <= numbers.length && in.hasNextInt()
D)currentSize <= numbers.length || in.hasNextInt()

Question 49

Which statements about array algorithms are true?
I.The array algorithms are building blocks for many programs that process arrays.
II.Java contains ready-made array algorithms for every problem situation.
III.It is inefficient to make multiple passes through an array if you can do everything in one pass.

A)I, II only
B)I, III only
C)II, III only
D)I, II, III

Question 50

Which code snippet finds the largest value in an array that is only partially full?

A)
B)
C)
D)

Question 51

Suppose you wish to use an array to solve a new problem.What is the first step to take in finding a solution?

A)structure a program using methods
B)adapt a built-in array algorithm
C)decompose the problem into steps
D)assemble a test program and run it

Question 52

The code snippet below is intended to perform a linear search on the array values to find the location of the value 42.What is the error in the code snippet?

A)The boolean variable found should be initialized to false.
B)The condition in the while loop should be (pos <= values.length && !found).
C)The variable pos should be initialized to 1.
D)The condition in the if statement should be (values[pos] <= searchedValue).

Question 53

This code snippet is an implementation of what algorithm?

A)removing an array element
B)finding the maximum value in an array
C)calculating the mean of values in an array
D)sequential search

Question 54

What will be printed by the statements below?

A)4 9 11 13
B)4 9 15 22
C)9 11 13 7
D)4 5 6 7

Question 55

Assume the method doSomething has been defined as follows: What does the method do?

A)It copies the integer array values to a new array.
B)It copies all but the first element in the integer array values to a new array.
C)It moves each element of the array values to a lower index position and overwrites the first element.
D)It overwrites all the values stored in the integer array values with the value stored in position 0.

Question 56

Consider using a deck of cards as a way to visualize a shuffle algorithm.When two cards shuffle their position, what has to happen to the size of the array holding them?

A)It increases by one.
B)It decreases by one.
C)It stays the same.
D)It increases by two.

Question 57

Assume the method doSomething has been defined as follows: What is printed by the statements below?
int [] nums = {3, 18, 29, -2} ;
System.out.print(Arrays.toString(doSomething(nums)));

A)[4, 19, 30, -1]
B)[21, 47, 27]
C)[21, 50, 48]
D)[3, 21, 47, 27]

Question 58

Assume the method doSomething has been defined as follows: What does the method do?

A)It copies the integer array values to a new array.
B)It swaps the integer values stored in positions p1 and p2 of the array values.
C)It moves each element of the array values to a higher index position.
D)It overwrites the value stored in the integer array values at position p1 with the value stored in position p2.

Question 59

The binary search is more efficient than the linear search, providing

A)the size of the array is a power of two.
B)the elements of the array are ordered.
C)the elements of the array are unordered.
D)the element being searched for is actually in the array.

Question 60

Assume the method doSomething has been defined as follows: What does the method do?

A)It copies the integer array values to a new array.
B)It swaps the integer values stored in positions i and i - 1 of the array values.
C)It moves each element of the array values to a lower index position and overwrites the first element.
D)It overwrites all the values stored in the integer array values with the value stored in position 0.

Question 61

Consider the following code snippet: What is the output of the given code snippet on execution?

A)5
B)7
C)9
D)10

Question 62

Consider the following 2-dimensional array.Which expression gives the number of elements in the third row?

A)counts[2].size()
B)counts.length[2]
C)counts.length
D)counts[2].length

Question 63

Why is the use of physical objects helpful in algorithm design?

A)It simulates the way the computer actually implements the algorithm.
B)It is more abstract than using a pencil and paper.
C)Because the constraints on physical things are the same as the constraints on bits and bytes.
D)Many people feel it is less intimidating than drawing diagrams.

Question 64

What is the output of the following code?

A)2
B)3
C)4
D)5

Question 65

Which one of the following is the correct definition for initializing data in a two-dimensional array with three rows and two columns?

A)
B)
C)
D)

Question 66

Which one of the following statements is the correct declaration for a two-dimensional array of 20 rows and 2 columns of type int?

A)int[][] num = new int[20][2];
B)int[][] num = new int[2][20];
C)int[][] num = new int[20,2];
D)int[][] num = new int[2,20];

Question 67

Assume the following variable has been declared and given a value as shown: Which is the value of data.length?

A)4
B)3
C)12
D)6

Question 68

Consider the following code snippet: What is the output of the given code snippet on execution?

A)5
B)6
C)7
D)9

Question 69

Consider the telephone book as a physical object that can help understand algorithms.What kind of algorithm might be visualized using it?

A)sorting
B)searching
C)finding the maximum
D)Monte Carlo methods

Question 70

Consider the following code snippet:
int val = arr[0][2];
Which value of arr is stored in the val variable?

A)the value in the first row and the second column
B)the value in the first row and the first column
C)the value in the first row and the third column
D)the value in the third row and the second column

Question 71

Assume the following variable has been declared and given a value as shown: Which is the value of data[1][2]?

A)0
B)17
C)15
D)2

Question 72

Which statement(s) about the size of a Java array, array list, and string are true?
I.The syntax for determining the size of an array, an array list, and a string in Java is consistent among the three.
II.The string uses s.size(), while the array list uses a.length().
III.The array uses a.length, which is not a method call.

A)I only
B)II only
C)III only
D)II, III only

Question 73

Which one of the following statements is correct for displaying the value in the second row and the third column of a two-dimensional, size 3 by 4 array?

A)System.out.println(arr[1][2]);
B)System.out.println(arr[2][3]);
C)System.out.println(arr[2][1]);
D)System.out.println(arr[3][2]);

Question 74

How many elements can be stored in an array of dimension 2 by 3?

A)2
B)3
C)5
D)6

Question 75

If a programmer confuses the method required for checking the length of a string and uses size() instead of length(), what will happen?

A)The program will crash.
B)The program will not compile.
C)The program will run but will produce an uncertain result.
D)The compiler will automatically correct the error.

Question 76

Consider the following code snippet: What is the value of numarray[1][2] after the code snippet is executed?

A)2
B)5
C)3
D)4

Question 77

Assume the following variable has been declared and given a value as shown: Which is the value of data[0].length?

A)21
B)12
C)4
D)3

Question 78

Which one of the following is a valid signature of a method with an integer two-dimensional array parameter of size 10 x 10?

A)public void func(int[][] arr)
B)public void func(int[10][] arr)
C)public void func(int[][10] arr)
D)public void func(int[10][10] arr)

Question 79

Consider the following code snippet: Identify the appropriate statement to display the value 24 from the given array?

A)System.out.println(arr[1][2]);
B)System.out.println(arr[2][2]);
C)System.out.println(arr[1][1]);
D)System.out.println(arr[2][1]);

Question 80

Consider the following code snippet: What is the output of the given code snippet?

A)00
B)31
C)30
D)03