C# - The Queue Class
The Queue class provides a number of properties and methods that are used to work with a queue, which is an abstract data structure that uses a first in, first out (FIFO) structure. A queue operates much like a line at a supermarket. The Queue class properties and methods are listed below.
Properties and Methods of the Queue Class
| Item | Description |
| Properties | |
| Count | Contains the number of items currently in the queue |
| IsReadOnly | Contains True if the queue is read-only and False otherwise |
| IsSynchronized | Contains True if the queue is synchronized and False otherwise |
| Methods | |
| Clear() | Clear all items from the queue |
| Clone() | Creates a duplicate of the queue |
| Contains() | Returns True if a given object is in the current queue |
| CopyTo() | Copies all or part of the current queue to another queue that is passed in as an argument |
| Dequeue() | Returns the next item from the queue and then removes it from the queue |
| Enqueue() | Adds a new object to the end of the queue |
| Peek() | Returns the next item from the queue but does not remove it |
| Synchronized() | Synchronizes the queue |
| ToArray() | Copies all or part of the current queue to an array |
Queue.Count
Syntax
Int32 Count
Description
The Queue.Count property contains the number of objects currently in the queue.
Example
Queue q = new Queue();
q.Enqueue("item1");
q.Enqueue("item2");
q.Enqueue("item3");
MyLabel.Text = "Count is "+q.Count.ToString();
Queue.IsReadOnly
Syntax
Boolean IsReadOnly
Description
The Queue.IsReadOnly property enables a developer to check the read-only status of a queue.
Example
Queue q = new Queue();
q.Enqueue("item1");
q.Enqueue("item2");
q.Enqueue("item3");
MyLabel.Text = "IsReadOnly set to " + q.IsReadOnly;
Queue.IsSynchronized
Syntax
Boolean IsSynchronized
Description
The Queue.IsSynchronized property enables a developer to check the synchronization of a queue.
Example
Queue q = new Queue();
q.Enqueue("item1");
q.Enqueue("item2");
q.Enqueue("item3");
MyLabel.Text = "IsSynchronized set to " + q.IsSynchronized;
Queue.Clear()
Syntax
Void Clear()
Description
The Queue.Clear() method removes all items from the queue.
Example
Queue q = new Queue();
q.Enqueue("item1");
q.Enqueue("item2");
q.Enqueue("item3");
q.Clear();
Queue.Clone()
Syntax
Object Clone()
Description
The Queue.Clone() method returns a queue that is identical to the one being cloned.
Example
Queue q = new Queue();
q.Enqueue("item1");
q.Enqueue("item2");
q.Enqueue("item3");
Queue q2 = (Queue)q.Clone();
Queue.Contains()
Syntax
Boolean Contains( Object obj )
Description
The Queue.Contains() method returns True if the argument obj is found in the queue.
Example
Queue q = new Queue();
q.Enqueue("item1");
q.Enqueue("item2");
q.Enqueue("item3");
MyLabel.Text = "Does queue contain this object: "+q.Contains("item2").ToString();
Queue.CopyTo()
Syntax
Void CopyTo(Array array, Int32 index)
Description
The Queue.CopyTo() method copies a queue to an array.
Example
Queue q = new Queue();
q.Enqueue("item1");
q.Enqueue("item2");
q.Enqueue("item3");
String[] MyArray = new String[3];
q.CopyTo(MyArray, 0);
MyLabel.Text = "Third item of queue is "+MyArray[2];
Queue.Dequeue()
Syntax
Object Dequeue()
Description
The Queue.Dequeue() method returns the object at the front of the queue and then removes it from the queue. If the queue is empty, InvalidOperationException is thrown at runtime.
Example
Queue q = new Queue();
q.Enqueue("item1");
q.Enqueue("item2");
q.Enqueue("item3");
q.Dequeue();
Queue.Enqueue()
Syntax
Void Enqueue( Object obj )
Description
The Queue.Enqueue() method puts an object or a value at the end of the queue.
Example
Queue q = new Queue(); q.Enqueue(35);
Queue.Peek()
Syntax
Object Peek()
Description
The Queue.Peek() method returns the object to the front of the queue, but it does not remove this object from the queue.
Example
Queue q = new Queue();
q.Enqueue("item1");
q.Enqueue("item2");
q.Enqueue("item3");
MyLabel.Text = "The next object in Queue is '"+q.peek()+"'";
Queue.Synchronized()
Syntax
Queue Synchronized( Queue queue )
Description
The Queue.Synchronized() method returns a synchronized copy of the current queue.
Example
Queue q = new Queue();
q.Enqueue("item1");
q.Enqueue("item2");
q.Enqueue("item3");
q = Queue.Synchronized(q);
MyLabel.Text = "True if items is synchronized: "+q.IsSynchronized;
Queue.ToArray()
Syntax
Object[] ToArray()
Description
The Queue.ToArray() method copies the current queue to an object array.
Example
Queue q = new Queue();
q.Enqueue("item1");
q.Enqueue("item2");
q.Enqueue("item3");
Object[] MyArray;
MyArray = q.ToArray();