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Java Queue and Map Interface
Question 1
Which class implements both the Queue and Deque interfaces in Java?
- A
Stack
- B
ArrayList
- C
ArrayDeque
- D
PriorityQueue
Question 2
What is the main difference between Queue and Deque interfaces?
- A
Queue allows LIFO and Deque allows FIFO
- B
Queue allows FIFO, Deque allows both FIFO and LIFO
- C
Queue does not allow null elements, Deque does
- D
Both are same
Question 3
Which queue class maintains natural ordering or uses a Comparator?
- A
ArrayDeque
- B
PriorityQueue
- C
LinkedList
- D
Stack
Question 4
What happens if you try to insert null into an ArrayDeque?
- A
It gets inserted
- B
NullPointerException
- C
Compiles but throws at runtime
- D
It replaces an existing null
Question 5
Which of the following allows insertion and deletion from both ends?
Queue
Stack
ArrayDeque
PriorityQueue
Question 6
What is the time complexity of offer() and poll() operations in a LinkedList-based queue?
- A
O(n)
- B
O(log n)
- C
O(n log n)
- D
O(1)
Question 7
Which method of HashMap is used to check if a key exists?
- A
containsKey()
- B
hasKey()
- C
keyExists()
- D
isKey()
Question 8
Which of the following is true about LinkedHashMap in Java?
- A
It does not maintain the insertion order
- B
It allows only unique values
- C
It maintains the insertion order
- D
It is slower than HashMap in terms of performance
Question 9
What is the time complexity of the get() method in a HashMap?
- A
O(log n)
- B
O(n)
- C
O(1)
- D
O(n^2)
Question 10
What does the TreeMap store in Java?
- A
Elements in random order
- B
Key-value pairs in ascending order of keys
- C
Only the keys, sorted
- D
Only the values, sorted
There are 16 questions to complete.
