Question

1.  

Suppose you must write a program that performs statistical calculations for a very large set of numerical data. Which would not be the best choices for storing such a collection if performance is important? (select all that apply)

Select one or more:

A. ArrayList

B. LinkedList

C. HashMap

D. An array of type int or double

2.

Which of the following statements is true?

Select one:

A. The Java map classes can access objects by reference values.

B. The Java LinkedList class can access objects by absolute values.

C. The Java map classes can access objects by key values.

D. The Java map classes can access objects by absolute values.

3.

Assume that myList is an ArrayList<Integer> object containing the elements 1 2 3 4 5 6. Assuming that each of the following statements is independent of the others, which would cause an error? (select all that apply)

Select one or more:

A. Object o = myList.remove(6);

B. myList.add(6, 9);

C. Integer o = myList.add(2.4);

D. Object o = myList.set(6, 8);

Answer 1

Question 1:
Time complexity of adding and searching an element in ArrayList, HashMap and array are O(1).
Where as for LinkedList is O(n)
Answer: B. LinkedList

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Question 2:
Map is a collection of key value pairs.
Answer: C. The Java map classes can access objects by key values.

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Question 3:
A. Object o = myList.remove(6);
This gives "java.lang.IndexOutOfBoundsException: Index 6 out of bounds for length 6"

C. Integer o = myList.add(2.4);
This gives compile time error because 2.4 is not an integer.

D. Object o = myList.set(6, 8);
This gives "java.lang.IndexOutOfBoundsException: Index 6 out of bounds for length 6"

Answers: Options A,C,D