LinkedBlockingDeque 在 Java 中的 descendingIterator() 方法

descendingIterator() 方法对于 LinkedBlockingDeque 返回一个迭代器，它按照相反的顺序迭代此 deque 中的元素。元素将按从最后（尾部）到第一个（头部）的顺序返回。返回的迭代器是“弱一致性（weakly consistent）”迭代器。

语法：

public Iterator descendingIterator()

参数： 此方法不接受任何参数。

返回值： 此方法返回一个按照相反顺序迭代此 deque 中元素的迭代器。

下面的程序说明了 LinkedBlockingDeque 的 descendingIterator() 方法：

程序1：

// Java Program 显示 descendingIterator()
// method of LinkedBlockingDeque
  
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
  
    {
  
        // create object of LinkedBlockingDeque
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>();
  
        // Add numbers to front of LinkedBlockingDeque
        LBD.addFirst(7855642);
        LBD.addFirst(35658786);
        LBD.addFirst(5278367);
        LBD.addFirst(74381793);
  
        // Call descendingIterator() method of LinkedBlockingDeque
        Iterator iteratorVals = LBD.descendingIterator();
  
        // Print elements of iterator
        // created from PriorityBlockingQueue
        System.out.println("The iterator values"
                           + " of LinkedBlockingDeque are:");
  
        // prints the elements using an iterator
        while (iteratorVals.hasNext()) {
            System.out.println(iteratorVals.next());
        }
    }
}

The iterator values of LinkedBlockingDeque are:
7855642
35658786
5278367
74381793

程序2：

// Java Program 显示 descendingIterator()
// method of LinkedBlockingDeque
// 当列表是字符串时
  
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
  
    {
  
        // create object of LinkedBlockingDeque
        LinkedBlockingDeque<String> LBD
            = new LinkedBlockingDeque<String>();
  
        // Add numbers to front of LinkedBlockingDeque
        LBD.add("Geeks");
        LBD.add("forGeeks");
        LBD.add("A");
        LBD.add("Computer");
        LBD.add("Portal");
  
        // Call iterator() method of LinkedBlockingDeque
        Iterator iteratorVals = LBD.descendingIterator();
  
        // Print elements of iterator
        // created from PriorityBlockingQueue
        System.out.println("The iterator values"
                           + " of LinkedBlockingDeque are:");
  
        // prints the elements using an iterator
        while (iteratorVals.hasNext()) {
            System.out.println(iteratorVals.next());
        }
    }
}

The iterator values of LinkedBlockingDeque are:
Portal
Computer
A
forGeeks
Geeks

参考： https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/LinkedBlockingDeque.html#descendingIterator()