C#

// Class that starts the calculation process - Sample Code seen on the web
        public class ClassThatCallsContextObject
        {
            public void StartCalculation ( )
            {
                decimal calculationResult = 0.0M;

                ContextObject contextObject;

                // Initilize the contextObject with the first calculation method
                contextObject = new ContextObject(new CalculationMethod1());
                calculationResult = contextObject.Calculation();
                // calculationResult would be set to 1.0

                // Initilize the contextObject with the second calculation method
                contextObject = new ContextObject(new CalculationMethod2());
                calculationResult = contextObject.Calculation();
                // calculationResult would be set to 2.0
            }
        }

// Define the possible calculation strategies
    public enum CalculationStrategies { Method1, Method2}

// Class that starts the calculation process - With User Selection
    public class ClassThatCallsContextObjectWithUserSelection
    {
        public void StartCalculation ( CalculationStrategies userInput )
        {
            decimal calculationResult = 0.0M;

            ContextObject contextObject;

            switch (userInput)
            {
                case CalculationStrategies.Method1:
                    // Initilize the contextObject with the first calculation method
                    contextObject = new ContextObject(new CalculationMethod1());
                    calculationResult = contextObject.Calculation();
                    // calculationResult would be set to 1.0
                    break;
                case CalculationStrategies.Method2:
                    // Initilize the contextObject with the second calculation method
                    contextObject = new ContextObject(new CalculationMethod2());
                    calculationResult = contextObject.Calculation();
                    // calculationResult would be set to 2.0
                    break;
            }
        }
    }

// Class that starts the calculation process
    public class ClassThatCallsContextObject
    {
        public void StartCalculation ()
        {
            decimal calculationResult = 0.0M;

            ContextObject contextObject = new ContextObject();
            calculationResult = contextObject.Calculation(CalculationStrategies.Method1);
            // calculationResult would be set to 1.0
            calculationResult = contextObject.Calculation(CalculationStrategies.Method2);
            // calculationResult would be set to 2.0
        }
    }

    // Define the possible calculation strategies
    public enum CalculationStrategies { Method1, Method2}

    // Class that executes the calculations
    public class ContextObject
    {
        // Constructor
        public ContextObject ()
        {

        }

        // Method that has multiple ways to calculate the value depending on user input
        public decimal Calculation ( CalculationStrategies selectedStrategy )
        {
            decimal calcualtedValue = 0.0M;
            switch (selectedStrategy)
            {
                case CalculationStrategies.Method1:
                    calcualtedValue = CalculationMethod1();
                    break;
                case CalculationStrategies.Method2:
                    calcualtedValue = CalculationMethod2();
                    break;
            }
            return calcualtedValue;
        }

        // Calculation Method 1
        private decimal CalculationMethod1 (  )
        {
            return 1.0M;
        }

        // Calculation Method 2
        private decimal CalculationMethod2 ()
        {
            return 2.0M;
        }
    }

// Class that starts the calculation process - Sample Code seen on the web
        public class ClassThatCallsContextObject
        {
            public void StartCalculation ( )
            {
                decimal calculationResult = 0.0M;

                ContextObject contextObject;

                // Initilize the contextObject with the first calculation method
                contextObject = new ContextObject(new CalculationMethod1());
                calculationResult = contextObject.Calculation();
                // calculationResult would be set to 1.0

                // Initilize the contextObject with the second calculation method
                contextObject = new ContextObject(new CalculationMethod2());
                calculationResult = contextObject.Calculation();
                // calculationResult would be set to 2.0
            }
        }

        // Define the possible calculation strategies
        public enum CalculationStrategies { Method1, Method2 }

        // Class that executes the calculations
        public class ContextObject
        {
            private ICalculationMethod _calculationMethod;

            // Constructor
            public ContextObject ( ICalculationMethod calculationMethod )
            {
                _calculationMethod = calculationMethod;
            }

            // Method that has multiple ways to calculate the value depending on user input
            public decimal Calculation ()
            {
                return _calculationMethod.CalculationMethod();
            }
        }

        interface ICalculationMethod
        {
            decimal CalculationMethod ();
        }

        public class CalculationMethod1 : ICalculationMethod
        {
            // Calculation Method 1
            private decimal CalculationMethod ()
            {
                return 1.0M;
            }
        }

        public class CalculationMethod2 : ICalculationMethod
        {
            // Calculation Method 2
            private decimal CalculationMethod ()
            {
                return 2.0M;
            }
        }