Java Collections Quiz

Which Java collection class is most suitable to represent a shopping cart where items can be accessed by index and duplicates are allowed?

• HashSet

• HashMap

• ArrayList

• TreeSet

In a school attendance system where each student should be marked present only once, which collection would you use?

• ArrayList

• HashSet

• TreeMap

• Stack

You are building a dictionary application where each word maps to its meaning. Which collection is best suited?

• LinkedList

• Stack

• HashMap

• TreeSet

Which collection would you use to store a list of students in the order of registration, without allowing duplicates?

• TreeMap

• LinkedHashSet

• PriorityQueue

• Hashtable

What will be the output of the following?

List list = new ArrayList<>();

list.add("A"); list.add("B"); list.add("A");

Set set = new HashSet<>(list);

System.out.println(set.size());

• 2

• 3

• Compilation Error

• Runtime Exception

What is the result of this code? List list = new ArrayList<>(); list.add("A"); list.add("B"); list.add(1, "C"); System.out.println(list);

• [A, B, C]

• [A, C, B]

• [C, A, B]

• Compilation Error

Consider this code: List list = Arrays.asList(1, 2, 3, 4, 5); list.set(2, 10); System.out.println(list);

• [1, 2, 10, 4, 5]

• [1, 10, 3, 4, 5]

• Compilation Error

• Runtime Exception

______ method is used to retrieve but not remove the head of the queue.

ArrayList is synchronized and thread-safe.

• True

• False

LinkedHashSet maintains the insertion order of elements.

• True

• False