Java ArrayDeque remove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>(8);

      // use add() method to add elements in the deque
      deque.add(25);
      deque.add(30);
      deque.add(20);
      deque.add(40);        

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

      // deque contains element 30, returns true
      boolean retval = deque.remove(30);
      if (retval == true) {
         System.out.println("element 30 is removed from the deque");
      } else {
         System.out.println("element 30 is not contained in the deque");
      }

      // deque does not contain element 15, returns false
      boolean returnval = deque.remove(15);
      if (returnval == true) {
         System.out.println("element 15 is removed from the deque");
      } else {
         System.out.println("element 15 is not contained in the deque");  
      }

      // printing remaining elements
      for (Integer number : deque) {
         System.out.println("Number = " + number);
      }  
   }  
}