. Net Strategy Mode

Directory

1. Definition
2. UML
3. Participants
4. Example

Definition:

PairAlgorithmIs the separation of algorithms and responsibilities.

UML:

Participants:

Abstract Policy (Strategy) Role: defines a method to implement the algorithm by an interface or abstract class.

Contretestrategy role: class used to implement the abstract role algorithm.

Environment (context) Role: Call a policy role.

Example:

 Code  Using System; Namespace Dofactory. gangoffour. Strategy. Structural { /// <Summary>    /// Mainapp startup class for structural    /// Strategy design pattern.   /// </Summary>    Class Mainapp { /// <Summary>      /// Entry point into console application.      /// </Summary>      Static   Void Main () {context; // Three contexts following different strategies Context = New Context ( New Concretestrategya (); context. contextinterface (); Context = New Context (New Concretestrategyb (); context. contextinterface (); Context = New Context ( New Concretestrategyc (); context. contextinterface (); // Wait for user Console. readkey ();}} /// <Summary>    // The 'strategy' abstract class    /// </Summary>    Abstract   Class Strategy { Public   Abstract   Void Algorithminterface ();} /// <Summary>    /// A' concretestrategy' class    /// </Summary>    Class Concretestrategya: Strategy { Public   Override   Void Algorithminterface () {console. writeline (" Called concretestrategya. algorithminterface () ");}} /// <Summary>    /// A' concretestrategy' class    /// </Summary>   Class Concretestrategyb: Strategy { Public   Override   Void Algorithminterface () {console. writeline (" Called concretestrategyb. algorithminterface () ");}} /// <Summary>    /// A' concretestrategy' class    /// </Summary>    Class Concretestrategyc: Strategy { Public   Override   Void Algorithminterface () {console. writeline (" Called concretestrategyc. algorithminterface () ");}} /// <Summary>    /// The 'context' class    /// </Summary>    Class Context { Private Strategy _ strategy; // Constructor      Public Context (strategy Strategy ){ This . _ Strategy = strategy ;} Public   Void Contextinterface () {_strategy. algorithminterface ();}}}

Output

Called concretestrategya. algorithminterface ()
Called concretestrategyb. algorithminterface ()
Called concretestrategyc. algorithminterface ()

Practical application:

 Code  Using System; Using System. Collections. Generic; Namespace Dofactory. gangoffour. Strategy. realworld { /// <Summary>    /// Mainapp startup class for real-world    /// Strategy design pattern.   /// </Summary>    Class Mainapp { /// <Summary>      /// Entry point into console application.      /// </Summary>      Static   Void Main (){ // Two contexts following different strategies Sortedlist studentrecords = New Sortedlist (); studentrecords. Add (" Samuel "); Studentrecords. Add (" Jimmy "); Studentrecords. Add ("Sandra "); Studentrecords. Add (" Vivek "); Studentrecords. Add (" Anna "); Studentrecords. setsortstrategy ( New Quicksort (); studentrecords. Sort (); studentrecords. setsortstrategy ( New Shellsort (); studentrecords. Sort (); studentrecords. setsortstrategy ( New Mergesort (); studentrecords. Sort (); // Wait for user Console. readkey ();}} /// <Summary>    // The 'strategy' abstract class   /// </Summary>    Abstract   Class Sortstrategy { Public   Abstract   Void Sort (list < String > List );} /// <Summary>    /// A' concretestrategy' class    /// </Summary>    Class Quicksort: sortstrategy { Public   Override   Void Sort (list < String > List) {list. Sort (); // Default is quicksort Console. writeline (" Quicksorted list ");}} /// <Summary>    /// A' concretestrategy' class    /// </Summary>    Class Shellsort: sortstrategy { Public   Override   Void Sort (list < String > List ){// List. shellsort (); Not-implemented Console. writeline (" Shellsorted list ");}} /// <Summary>    /// A' concretestrategy' class    /// </Summary>    Class Mergesort: sortstrategy { Public   Override   Void Sort (list < String > List ){ // List. mergesort (); Not-implemented Console. writeline ("Mergesorted list ");}} /// <Summary>    /// The 'context' class    /// </Summary>    Class Sortedlist { Private List < String > _ List = New List < String > (); Private Sortstrategy _ sortstrategy; Public   Void Setsortstrategy (sortstrategy ){ This . _ Sortstrategy = sortstrategy ;} Public   Void Add ( String Name) {_ list. Add (name );} Public   Void Sort () {_ sortstrategy. Sort (_ list ); // Iterate over list and Display Results        Foreach ( String Name In _ List) {console. writeline ("   "+ Name) ;}console. writeline ();}}}

Output

Quicksorted list
Anna
Jimmy
Samuel
Sandra
Vivek
Shellsorted list
Anna
Jimmy
Samuel
Sandra
Vivek
Mergesorted list
Anna
Jimmy
Samuel
Sandra
Vivek