Java程序实现ArrayDeque API

ArrayDeque在Java中提供了如何使用resizable-array另外实现的Deque接口。它也被称为Array Double Ended Queue或Array Deck。这是一个特殊的相当数组，它可以增长，并允许用户从队列的每一边特征或删除一个组件。

java.lang.Object

    java.util.AbstractCollection<E>

        java.util.ArrayDeque<E>

层次结构中ArrayDeque的所有实现接口是。

Serializable,
Cloneable,
Iterable,
Collection
Deque
Queue

阵列deques没有任何容量限制；它们根据需要增长以支持使用。它们不是线程安全的；在没有外部同步的情况下，它们不支持多线程的并发访问。空元素是被禁止的。这个类作为堆栈使用时可能比Stack快，作为队列使用时比LinkedList快。

实现:

// Java program to demonstrate implementation
// of ArrayDeque
  
import java.util.*;
public class ArrayDequeExample {
    public static void main(String[] args)
    {
        // Initializing an deque
        Deque<Integer> de_que = new ArrayDeque<Integer>(10);
  
        // add() method to insert
        de_que.add(10);
        de_que.add(20);
        de_que.add(30);
        de_que.add(40);
        de_que.add(50);
  
        for (Integer element : de_que) {
            System.out.println("Element : " + element);
        }
  
        System.out.println("Using clear() ");
  
        // clear() method
        de_que.clear();
  
        // addFirst() method to insert at start
        de_que.addFirst(564);
        de_que.addFirst(291);
  
        // addLast() method to insert at end
        de_que.addLast(24);
        de_que.addLast(14);
  
        System.out.println(
            "Above elements have been cleared");
  
        // Iterator() :
        System.out.println(
            "Elements of deque using Iterator :");
  
        for (Iterator itr = de_que.iterator();
             itr.hasNext();) {
            System.out.println(itr.next());
        }
  
        // descendingIterator() : to reverse the deque order
        System.out.println(
            "Print elements in reverse order :");
  
        for (Iterator dItr = de_que.descendingIterator();
             dItr.hasNext();)
        {
            System.out.println(dItr.next());
        }
  
        // element() method : to get Head element
        System.out.println(
            "\nHead Element using element(): "
            + de_que.element());
  
        // getFirst() method : to get Head element
        System.out.println(
            "Getting Head Element using getFirst(): "
            + de_que.getFirst());
  
        // getLast() method : to get last element
        System.out.println(
            "Getting Last Element using getLast(): "
            + de_que.getLast());
  
        // toArray() method :
        Object[] arr = de_que.toArray();
  
        System.out.println("\nArray Size : " + arr.length);
  
        System.out.print("Array elements : ");
  
        for (int i = 0; i < arr.length; i++)
            System.out.print(" " + arr[i]);
  
        // peek() method : to get head
        System.out.println("\nHead element : "
                           + de_que.peek());
  
        // poll() method : to get head
        System.out.println("Head element poll : "
                           + de_que.poll());
  
        // push() method :
        de_que.push(265);
        de_que.push(984);
        de_que.push(2365);
  
        // remove() method : to get head
        System.out.println("Head element remove : "
                           + de_que.remove());
  
        System.out.println("Final Array: " + de_que);
    }
}

输出

Element : 10
Element : 20
Element : 30
Element : 40
Element : 50
Using clear() 
Above elements have been cleared
Elements of deque using Iterator :
291
564
24
14
Print elements in reverse order :
14
24
564
291

Head Element using element(): 291
Getting Head Element using getFirst(): 291
Getting Last Element using getLast(): 14

Array Size : 4
Array elements :  291 564 24 14
Head element : 291
Head element poll : 291
Head element remove : 2365
Final Array: [984, 265, 564, 24, 14]