Java ArrayDeQue addFirst方法

package com.codingdict;

import java.util.ArrayDeque;
import java.util.Deque;

public class ArrayDequeDemo {
   public static void main(String[] args) {

      // create an empty array deque with an initial capacity
      Deque<Integer> deque = new ArrayDeque<Integer>(5);

      // use add() method to add elements in the deque
      deque.add(25);
      deque.add(30);
      deque.add(35);

      // use addFirst() method to add element at the front of the deque
      deque.addFirst(10);
      deque.addFirst(15);
      deque.addFirst(20);//now, element 20 will be at the front

      // these elments will be added in continuation with deque.add(35)
      deque.add(45);
      deque.add(40);

      // let us print all the elements available in deque
      for (Integer number : deque) {
         System.out.println("Number = " + number);
      }
   }
}