Java quiz 20 MCQS

Question 1(5 points)

Question 1 Unsaved

[removed]

Method A invokes method A itself. This is called _________.

Question 1 options:

[removed]	indirect recursion
[removed]	explicit recursion
[removed]	direct recursion
[removed]	one-step recursion

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Question 2(5 points)

Question 2 Unsaved

[removed]

What are the base cases in the following recursive method?

public static void recurse(int n)
{
if (n > 0)
{
System.out.print(n % 10);
recurse(n / 10);
}
}

Question 2 options:

[removed]	n < 0
[removed]	n <= 0
[removed]	n > 0
[removed]	no base cases

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Question 3(5 points)

Question 3 Unsaved

[removed]

What will be displayed by the method call recurse(1234)?

public static void recurse(int n)
{
if (n <= 0)
{
System.out.print(n % 10);
recurse(n / 10);
}
}

Question 3 options:

[removed]	1234
[removed]	4 3 2 1
[removed]	Nothing
[removed]	4321

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Question 4(5 points)

Question 4 Unsaved

[removed]

Analyze the following recursive method and indicate which of the following will be true.

public static long factorial(int n)
{
return n * factorial(n - 1);
}

Question 4 options:

[removed]	Invoking factorial(2) returns 2.
[removed]	Invoking factorial(1) returns 1.
[removed]	The method runs infinitely and causes a StackOverflowError.
[removed]	Invoking factorial(0) returns 0.

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Question 5(5 points)

Question 5 Unsaved

[removed]

Fill in the code to complete the following method for computing factorial.

// Return the factorial for a specified index
public static long factorial(int n)
{
if (n == 0)
return 1;
else
return _____________;
}

Question 5 options:

[removed]	n * (n - 1)
[removed]	n
[removed]	n * factorial(n - 1)
[removed]	factorial(n - 1) * (n - 1)

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Question 6(5 points)

Question 6 Unsaved

[removed]

What will be displayed by the method call recurse(6)?

public static intrecurse(int n)
{
if (n <= 1)
return 1;
else
return n + recurse(n - 2);
}

Question 6 options:

[removed]	13
[removed]	14
[removed]	11
[removed]	12

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Question 7(5 points)

Question 7 Unsaved

[removed]

The base case _________ the recursion.

Question 7 options:

[removed]	stops
[removed]	breaks
[removed]	pauses
[removed]	starts

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Question 8(5 points)

Question 8 Unsaved

[removed]

What is the output of the following program?

{
public static void main(String[] args)
{
System.out.println(countDown(2, 0));
}
public static intcountDown(int n, int result)
{
if (n == 0)
return 0;
else
return countDown(n - 1, n + result);
}
}

Question 8 options:

[removed]	1
[removed]	3
[removed]	0
[removed]	2

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Question 9(5 points)

Question 9 Unsaved

[removed]

Which of the following statements about recursive methods is accurate?

Question 9 options:

[removed]	They must have exactly 1 base case and exactly 1 recursive case
[removed]	They must have at least 1 base case and at least 1 recursive case
[removed]	They must have exactly 1 base case and at least 1 recursive case
[removed]	They must have at least 1 base case and exactly 1 recursive case

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Question 10(5 points)

Question 10 Unsaved

[removed]

Which of the following is a possible disadvantage of recursion?

Question 10 options:

[removed]	Recursive solutions can be less efficient than their iterative counterparts
[removed]	Recursive solutions tend to have more local variables than their iterative counterparts
[removed]	Recursive solutions tend to be longer than their iterative counterparts
[removed]	Recursive solutions are more likely to go into infinite loops than their iterative counterparts

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Question 11(5 points)

Question 11 Unsaved

[removed]

To declare an interface named A with two generic types, use

Question 11 options:

[removed]	public interface A(E) { ... }
[removed]	public interface A<E, F> { ... }
[removed]	public interface A<E> { ... }
[removed]	public interface A(E, F) { ... }

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Question 12(5 points)

Question 12 Unsaved

[removed]

Will the following code have a runtime error?

Comparable date = new Date();
inti = date.compareTo("time");

Question 12 options:

[removed]	Always
[removed]	Never
[removed]	Only when date contains an invalid date
[removed]	Only when date is not the current date

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Question 13(5 points)

Question 13 Unsaved

[removed]

To create a list to store integers, use

Question 13 options:

[removed]	ArrayList<Object> list = new ArrayList<Integer>();
[removed]	ArrayList<Number> list = new ArrayList<Integer>();
[removed]	ArrayList<int> list = new ArrayList();
[removed]	ArrayList<Integer> list = new ArrayList();

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Question 14(5 points)

Question 14 Unsaved

[removed]

To create a generic type bounded by Number, use

Question 14 options:

[removed]	<E extends Object>
[removed]	<E extends Number>
[removed]	<E>
[removed]	<E extends Integer>

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Question 15(5 points)

Question 15 Unsaved

[removed]

Which of the following describes the benefit of using generic classes to implement collections?

Question 15 options:

[removed]	It eliminates the need to downcast objects when they are removed from a collection
[removed]	It eliminates the need to upcast objects when they are inserted into a collection
[removed]	It eliminates the need to downcast objects when they are inserted into a collection
[removed]	It eliminates the need to upcast objects when they are removed from a collection

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Question 16(5 points)

Question 16 Unsaved

[removed]

Suppose list list1 is [1, 2, 5] and list list2 is [2, 3, 6]. After list1.addAll(list2), list2 is __________.

Question 16 options:

[removed]	[1, 5]
[removed]	[1, 2, 3, 5, 6]
[removed]	[2, 3, 6]
[removed]	[1, 2, 2, 3, 5, 6]

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Question 17(5 points)

Question 17 Unsaved

[removed]

Suppose a list contains {red, red, red, red}. What is the list after the following code?

String element = "red";
for (inti = list.size() - 1; i>= 0; i--)
if (list.get(i).equals(element))
list.remove(element);

Question 17 options:

[removed]	[red]
[removed]	[red, red]
[removed]	[]
[removed]	[red, red, red]

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Question 18(5 points)

Question 18 Unsaved

[removed]

Which of the following is correct to sort the elements in a list aList?

Question 18 options:

[removed]	Arrays.sort(aList)
[removed]	new LinkedList<String>(new String[]{red, green, blue})
[removed]	Collections.sort(aList)
[removed]	aList.sort()

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Question 19(5 points)

Question 19 Unsaved

[removed]

Which of the following best describes all objects of type List?

Question 19 options:

[removed]	They define an ordered collection that prohibits duplicates
[removed]	They define an ordered collection that allows duplicates
[removed]	They define an unordered collection that allows duplicates
[removed]	They define an unordered collection that prohibits duplicates

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Question 20(5 points)

Question 20 Unsaved

[removed]

Which of the following problems would be a good candidate for using a stack?

Question 20 options:

[removed]	A print spooler that dispatches jobs based on shortest job first
[removed]	An inventory system that processes product records by product number
[removed]	A program that is designed to evaluate expressions
[removed]	A task scheduler that schedules tasks in the order that they are received

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