The **`dart:collection`** library provides advanced collection support for the Dart language. The library contains the **`DoubleLinkedQueue<E>` class**, which uses a doubly-linked list to implement the abstract `Queue<E>` class.

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## The addAll() method
The `DoubleLinkedQueue<E>` class contains the **`addAll()` method** which is used to add the elements of a specified input collection to the end of the queue. The queue's length is extended by the input collection's length.

>A queue is a FIFO (first in first out) data structure. In a queue, the element that is added first will be deleted first.

The figure below illustrates how the `addAll()` method works:

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#  Syntax
The syntax of the `addAll()` method is as follows:
```
void addAll(Iterable<E> iterable)
```

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#  Parameters
The `addAll()` method takes a collection of elements as input and adds all elements to the end of the queue.

##     
## Return value
`addAll()` does not return any value.

##       
## Code
The code below shows how the `addAll()` method works in Dart:

import 'dart:collection'; 
void main() { 
   var monthQueue = DoubleLinkedQueue<String>();
   
   monthQueue.add("January"); 
   monthQueue.add("February"); 
   monthQueue.add("March");   
   print('Queue : $monthQueue');
   var otherList = ["April","May"];
   print('List : $otherList');

   monthQueue.addAll(otherList);

   print('Queue after addAll() : $monthQueue');
}


#      
## Explanation
- Line 3: We create an instance named `monthQueue` of `DoubleLinkedQueue` class of type `String`.
- Lines 5-7: Next, we use the `add()` method to add a few strings to the queue: `"January"`, `"February"`, and `"March"`.
- Line 9: We create a list of strings and add `"April"` and `"May"` to it.

- Line 12: We now call the `addAll()` method and pass the list created above as input. It adds all list elements to the end of the queue, as the queue is a FIFO data structure.

- Line 14: We use the `print()` function of the core library to display the queue and list elements.

What is DoublyLinkedQueue.addAll() method in Dart?

The dart:collection library provides advanced collection support for the Dart language. The library contains the DoubleLinkedQueue class, which uses a doubly-linked list to implement the abstract Queue class.  The addAll() method The DoubleLinkedQueue class contains the addAll() method which is used to add the elements of a specified input collection to the end of the queue. The queue s length is extended by the input collection s length.  A queue is a FIFO (first in first out) data structure. In a queue, the element that is added first will be deleted first.  The figure below illustrates how the addAll() method works: 