omniright.blogg.se - Poll java queue

POLL JAVA QUEUE FULL
POLL JAVA QUEUE CODE

The elementmethod on the other hand throws a NoSuchElementException. The only difference is that if the queue is empty, the peekmethod returns a null. So it returns the element at the head of the queue without removing it. Since the queue is empty, this causes a NoSuchElementExceptionĮxception in thread "main" Īt java.base/(LinkedList.java:248)Īt java.base/(LinkedList.java:667)Īt (QueueDemo.java:18) peek.Line 9 uses the element method to retrieve the head of the queue.Line 8 initializes the daysOfTheWeek Queue to a new empty Queue.Since the call at Line 3 does not remove the value, this call also returns Monday Line 5 again uses the element method again to retrieve the head of the queue.Line 3 uses the element method to retrieve the head of the queue, in this case Monday. It does not remove this value from the queue.It throws a NoSuchElementException if the queue is empty. The elementmethod returns the head of the queue but does not remove it from the queue. Line 4 again invokes the poll method which returns a null since the queue is empty.Line 3 uses the poll method to remove the head of the queue, in this case Monday.Lines 2 uses the add method to add the value Monday to the queue.Sample Code: Queue daysOfTheWeek = new LinkedList() The removemethod on the other hand throws a NoSuchElementException. The only difference is that if the queue is empty, the pollmethod returns a null.

So it removes the element at the head of the queue. Output: Exception in thread "main" Īt java.base/(LinkedList.java:274)Īt java.base/(LinkedList.java:689)Īt (QueueDemo.java:11) poll

Since the Queue is empty, it causes a NoSuchElementException.

Line 5 uses the remove method to remove the head of the queue, in this case MondayĪs mentioned earlier, when you invoke removeon an empty queue, it throws a NoSuchElementException Queue daysOfTheWeek = new LinkedList().

POLL JAVA QUEUE CODE

Sample Code (Non-empty Queue) Queue daysOfTheWeek = new LinkedList() If the queue is empty, it throws a NoSuchElementException It removes the element at the head of the queue. The removemethods helps removing a value from a Queue.

POLL JAVA QUEUE FULL

Lines 4 uses the offer method to add the value Monday which returns false since the queue is full.

Lines 2 uses the offer method to add the value Monday which returns true.

Sample Code Queue daysOfTheWeek = new ArrayBlockingQueue(1) īoolean added = daysOfTheWeek.offer("Monday") The only difference is if for some reason the offer method is unable to add an element to the queue, it returns a false. So it adds an element at the head of the queue. : Queue fullĪt java.base/(AbstractQueue.java:98)Īt java.base/.add(ArrayBlockingQueue.java:326)Īt (QueueDemo.java:14) offer

Since this is a Queue with size 1, Line 4 causes an exception.

Line 4 uses the add method to add the value Tuesday.

Line 2 uses the add method to add the value Monday which returns true.

It uses the ArrayBlockingQueue implementation and specifies the size as 1 Queue daysOfTheWeek = new ArrayBlockingQueue(1) īoolean added = daysOfTheWeek.add("Monday") However it is evident for the ArrayBlockingQueue implementation which has a capacity restriction.

This behaviour is not evident when you use the LinkedList implementation of a Queue.

Lines 2-4 use the add method to add some values to the queueĪs mentniod earlier, if the add method is unable to add the element, it throws an Exception.

Sample Code (Without Exception) Queue daysOfTheWeek = new LinkedList() if for some reason the add method is unable to add the element, it throws an Exception. The addmethod supports adding an element to the Queue. There are several methods available on the queue interface that help to perform various queue operations. The and are the most common implementations Java Queue Interface Operations It has several implementations in the Collection API. It provides a First In First Out (FIFO) behavior and you can use it to represent a Queue data structure.