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