C# in Depth

100 CHAPTER 3 Parameterized typing with genericsJust as with List, there is no way of obtaining a synchronized Dictionary,nor does it implement ICloneable. The dictionary equivalent of Synchronized-Collection is SynchronizedKeyedCollection (which in fact derives fromSynchronizedCollection).With the lack of additional functionality, another example of Dictionarywould be relatively pointless. Let’s move on to two types that are closely related toeach other: Queue and Stack.3.5.3 Queue and StackThe generic queue and stack classes are essentially the same as their nongeneric counterparts.The same features are “missing” from the generic versions as with the othercollections—lack of cloning, and no way of creating a synchronized version. Asbefore, the two types are closely related—both act as lists that don’t allow randomaccess, instead only allowing elements to be removed in a certain order. Queues act ina first in, first out (FIFO) fashion, while stacks have last in, first out (LIFO) semantics.Both have Peek methods that return the next element that would be removed butwithout actually removing it. This behavior is demonstrated in listing 3.14.Listing 3.14Demonstration of Queue and StackQueue queue = new Queue();Stack stack = new Stack();for (int i=0; i < 10; i++){queue.Enqueue(i);stack.Push(i);}for (int i=0; i < 10; i++){Console.WriteLine ("Stack:{0} Queue:{1}",stack.Pop(), queue.Dequeue());}The output of listing 3.14 is as follows:Stack:9 Queue:0Stack:8 Queue:1Stack:7 Queue:2Stack:6 Queue:3Stack:5 Queue:4Stack:4 Queue:5Stack:3 Queue:6Stack:2 Queue:7Stack:1 Queue:8Stack:0 Queue:9You can enumerate Stack and Queue in the same way as with a list, but in myexperience this is used relatively rarely. Most of the uses I’ve seen have involved athread-safe wrapper being put around either class, enabling a producer/consumerLicensed to Rhona Hadida