JAVA-QUEUE

PriorityQueue<Integer> pq = new PriorityQueue<>();

pq.add(50);

pq.add(10);

pq.add(40);

System.out.println(pq);

• [50, 10, 40]

• [10, 40, 50]

• Random order

• error

Queue<Integer> q = new ArrayDeque<>();

q.add(1);

q.add(2);

q.add(3);

q.remove();

q.remove();

q.add(4);

System.out.println(q.peek());

• 1

• 2

• 3

• 4

Which of the following is true about Java Queue?

• add() throws exception if queue is full, offer() returns false.

• remove() returns null if queue is empty.

• poll() throws exception if queue is empty.

• peek() throws exception if queue is empty.

Deque<Integer> dq = new ArrayDeque<>();

dq.addFirst(10);

dq.addLast(20);

dq.addLast(30);

dq.removeFirst();

dq.addFirst(40);

System.out.println(dq);

• [10, 20, 30]

• [20, 30, 40]

• [40, 20, 30]

• [40, 10, 20]

Queue<Integer> q = new LinkedList<>();

System.out.println(q.poll());

System.out.println(q.remove());

• null, null

• null, Exception

• Exception, null

• Exception, Exception

PriorityQueue<String> pq = new PriorityQueue<>();

pq.add("banana");

pq.add("apple");

pq.add("cherry");

System.out.println(pq.poll());

System.out.println(pq.peek());

• banana, apple

• apple, banana

• apple, cherry

• banana, cherry

Queue<Integer> q = new LinkedList<>();

q.add(null);

System.out.println(q.peek());

• null

• Compilation error

• Runtime exception

• undefined behavior

Queue<Integer> q = new ArrayDeque<>(2);

q.offer(10);

q.offer(20);

System.out.println(q.add(30));

• true

• false

• Exception

• null

PriorityQueue<Integer> pq =

new PriorityQueue<>((a, b) -> (a % 2) - (b % 2));

pq.add(5);

pq.add(2);

pq.add(3);

System.out.println(pq.poll() + " " + pq.poll());

• 2 5

• 2 3

• 3 5

• Unpredictable

PriorityQueue<Integer> pq = new PriorityQueue<>();

pq.add(4);

pq.add(1);

pq.add(3);

for (int x : pq)

System.out.print(x + " ");

• 1 3 4

• 4 1 3

• Unpredictable internal order

• Compilation error