The
poll() method of
Queue Interface returns and removes the element at the front end of the container. It deletes the element in the container. The method does not throws an exception when the Queue is empty, it returns
null instead.
Syntax:
E poll()
Returns: This method returns the
element at the front of the container or the head of the Queue. It returns
null when the Queue is empty.
Below programs illustrate poll() method of Queue:
Program 1: With the help of
LinkedList.
Output:
Queue: [7855642, 35658786, 5278367, 74381793]
Queue's head: 7855642
Queue's head: 35658786
Program 2: To Demonstrate poll() method of Queue when the Queue becomes empty
Output:
Queue: [423, 3432]
Queue's head: 423
Queue's head: 3432
Queue: []
Queue's head: null
Program 3: With the help of
ArrayDeque.
Output:
Queue: [7855642, 35658786, 5278367, 74381793]
Queue's head: 7855642
Queue's head: 35658786
Program 4: With the help of
ConcurrentLinkedDeque.
Output:
Queue: [7855642, 35658786, 5278367, 74381793]
Queue's head: 7855642
Queue's head: 35658786
Program 5: With the help of
LinkedBlockingDeque.
