Java quiz 20 MCQS

Question 1(5 points) 

Method A invokes method A itself. This is called _________.
Question 1 options:







indirect recursion







explicit recursion







direct recursion







one-step recursion




Save
Question 2(5 points)
 

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:







n < 0







n <= 0







n 0







no base cases




Save
Question 3(5 points)
 

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:







1234







4 3 2 1







Nothing







4321




Save
Question 4(5 points)
 

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:







Invoking factorial(2) returns 2.







Invoking factorial(1) returns 1.







The method runs infinitely and causes a StackOverflowError.







Invoking factorial(0) returns 0.




Save
Question 5(5 points)
 

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:







n * (n - 1)







n







n * factorial(n - 1)







factorial(n - 1) * (n - 1)




Save
Question 6(5 points)
 

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:







13







14







11







12




Save
Question 7(5 points)
 

The base case _________ the recursion.
Question 7 options:







stops







breaks







pauses







starts




Save
Question 8(5 points)
 

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:







1







3







0







2




Save
Question 9(5 points)
 

Which of the following statements about recursive methods is accurate?
Question 9 options:







They must have exactly 1 base case and exactly 1 recursive case







They must have at least 1 base case and at least 1 recursive case







They must have exactly 1 base case and at least 1 recursive case







They must have at least 1 base case and exactly 1 recursive case




Save
Question 10(5 points)
 

Which of the following is a possible disadvantage of recursion?
Question 10 options:







Recursive solutions can be less efficient than their iterative counterparts







Recursive solutions tend to have more local variables than their iterative counterparts







Recursive solutions tend to be longer than their iterative counterparts







Recursive solutions are more likely to go into infinite loops than their iterative counterparts




Save
Question 11(5 points)
 

To declare an interface named A with two generic types, use
Question 11 options:







public interface A(E) { ... }







public interface A<E, F { ... }







public interface A<E { ... }







public interface A(E, F) { ... }




Save
Question 12(5 points)
 

Will the following code have a runtime error?

Comparable date = new Date();
inti = date.compareTo("time");
Question 12 options:







Always







Never







Only when date contains an invalid date







Only when date is not the current date




Save
Question 13(5 points)
 

To create a list to store integers, use
Question 13 options:







ArrayList<Object list = new ArrayList<Integer();







ArrayList<Number list = new ArrayList<Integer();







ArrayList<int list = new ArrayList();







ArrayList<Integer list = new ArrayList();




Save
Question 14(5 points)
 

To create a generic type bounded by Number, use
Question 14 options:







<E extends Object







<E extends Number







<E







<E extends Integer




Save
Question 15(5 points)
 

Which of the following describes the benefit of using generic classes to implement collections?
Question 15 options:







It eliminates the need to downcast objects when they are removed from a collection







It eliminates the need to upcast objects when they are inserted into a collection







It eliminates the need to downcast objects when they are inserted into a collection







It eliminates the need to upcast objects when they are removed from a collection




Save
Question 16(5 points)
 

Suppose list list1 is [1, 2, 5] and list list2 is [2, 3, 6]. After list1.addAll(list2), list2 is __________.
Question 16 options:







[1, 5]







[1, 2, 3, 5, 6]







[2, 3, 6]







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




Save
Question 17(5 points)
 

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:







[red]







[red, red]







[]







[red, red, red]




Save
Question 18(5 points)
 

Which of the following is correct to sort the elements in a list aList?
Question 18 options:







Arrays.sort(aList)







new LinkedList<String(new String[]{red, green, blue})







Collections.sort(aList)







aList.sort()




Save
Question 19(5 points)
 

Which of the following best describes all objects of type List?
Question 19 options:







They define an ordered collection that prohibits duplicates







They define an ordered collection that allows duplicates







They define an unordered collection that allows duplicates







They define an unordered collection that prohibits duplicates




Save
Question 20(5 points)
 

Which of the following problems would be a good candidate for using a stack?
Question 20 options:







A print spooler that dispatches jobs based on shortest job first







An inventory system that processes product records by product number







A program that is designed to evaluate expressions







A task scheduler that schedules tasks in the order that they are received




Save
Powered by