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copied!<p>Always use the Strategy design pattern for operations like this below.</p> <p>//StrategyExample test application</p> <p>public class StrategyExample { public static void main(String[] args) { Context context; // Three contexts following different strategies context = new Context(new ConcreteStrategyAdd()); int resultA = context.executeStrategy(3, 4); context = new Context(new ConcreteStrategySubtract()); int resultB = context.executeStrategy(3, 4); context = new Context(new ConcreteStrategyMultiply()); int resultC = context.executeStrategy(3, 4); } }</p> <p>//The classes that implement a concrete strategy should implement this // The context class uses this to call the concrete strategy public interface Strategy { int execute(int a, int b); }</p> <p>//Implements the algorithm using the strategy interface public class ConcreteStrategyAdd implements Strategy { public int execute(int a, int b) { System.out.println("Called ConcreteStrategyA's execute"); return a + b; // Do an addition with a and b } }</p> <p>public class ConcreteStrategySubtract implements Strategy { public int execute(int a, int b) { System.out.println("Called ConcreteStrategyB's execute()"); return a - b; // Do a subtraction with a and b } }</p> <p>public class ConcreteStrategyMultiply implements Strategy { public int execute(int a, int b) { System.out.println("Called ConcreteStrategyC's execute()"); return a * b; // Do a multiplication with a and b } }</p> <p>//Configured with a ConcreteStrategy object and maintains a reference to a Strategy object public class Context { private Strategy strategy;</p> <pre><code>// Constructor public Context(Strategy strategy) { this.strategy = strategy; } public int executeStrategy(int a, int b) { return strategy.execute(a, b); } </code></pre> <p>}</p>

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