Double-ended queues in Java and their use

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 Packagecollections;ImportJava.util.Deque;Importjava.util.LinkedList;/*** @Package Collections * @date 2017-11-28 PM 5:53:32*/ Public classDequetest {/**     * @paramargs*/     Public Static voidMain (string[] args) {Deque<String> deque =NewLinkedlist<string>(); Deque.add ("D"); Deque.add (E); Deque.add ("F"); //Remove element from first team, not deleteSYSTEM.OUT.PRINTLN ("Team first Take out element:" +Deque.peek ()); System.out.println ("Queue is:" +deque); //add elements from the first team (queue with capacity limit, none with AddFirst)Deque.offerfirst ("C"); System.out.println ("When the team first joins the element:" +deque); //add elements from the end of the queue (queues have capacity constraints, none are used AddLast)Deque.offerlast ("G"); System.out.println ("After adding elements to the end of the team:" +deque); //Team Tail add elementDeque.offer ("H"); System.out.println ("After adding elements to the end of the team:" +deque); //gets and removes the first element of the queue, Pollfirst () is also, except that the Removefirst throws a Nosuchelementexception exception when the queue is empty, which returns nullDeque.removefirst (); System.out.println ("Gets and removes the first element of a queue after:" +deque); //gets and removes the first element of the queue, the only difference between this method and Polllast is that when the queue is empty, Removelast throws a Nosuchelementexception exception, which returns nullDeque.removelast (); System.out.println ("Gets and removes the last element of the queue after:" +deque); //gets the first element of the queue. The only difference between this method and Peekfirst is that if this double-ended queue is empty, it throws nosuchelementexception, which returns nullSystem.out.println ("Get queue first element is:" +Deque.getfirst ()); System.out.println ("Gets the first element of the queue after:" +deque); //gets the last element of the queue. The only difference between this method and Peeklast is that if this double-ended queue is empty, it throws nosuchelementexception, which returns nullSystem.out.println ("Get queue last element is:" +deque.getlast ()); System.out.println ("Gets the first element of the queue after:" +deque); //Loop get elements and remove elements from queue         while(Deque.size () >0) {System.out.println ("Get element is:" + deque.pop () + "and delete"); } System.out.println ("Queue is:" +deque); }}

The results are as follows:

First team take out elements: D queue for: [D, E, F] The first element of the team is: [C, D, E, F] After adding elements: [C, D, E, F, G] at the end of the team: [C, D, E, F, G, H] gets and removes the first element of the queue: [D, E, F, G, H ] Gets and removes the last element of the queue after: [D, E, F, G] Gets the queue the first element is: D gets the queue after the first element is: [D, E, F, G] Gets the queue the last element is: G Gets the queue after the first element is: [D, E, F, g] gets the element: D and removes the Get element as: E and remove the Get element as: F and remove the get element as: G and delete the queue as: []

Double-ended queues in Java and their use