1. Introduction to Design Patterns

• Definition of a design pattern.
• Purpose and benefits of design patterns.
  • Reusability
  • Readability
  • Modularity
  • Scalability
• Categories of design patterns:
  • Creational
  • Structural
  • Behavioral

2. Dive into Behavioral Patterns

• Brief explanation of Behavioral patterns.
• Emphasis on how they handle object collaboration and responsibilities.

3. Introduction to the Strategy Pattern

• Definition of the Strategy pattern.
• Objective: Define a family of algorithms, encapsulate each one, and make them interchangeable.
• Key components:
  • Context
  • Strategy
  • ConcreteStrategy

4. Real-life analogy for Strategy Pattern

• Example: Different travel modes (walking, driving, flying) to reach a destination.

5. Code Examples

5.1. Class Diagram for Strategy Pattern

   Context
     |
 Strategy <--- ConcreteStrategy1
          <--- ConcreteStrategy2
          <--- ConcreteStrategy3

5.2. Basic Implementation

// Strategy
public interface TravelStrategy {
    String travel();
}

// ConcreteStrategies
public class WalkStrategy implements TravelStrategy {
    @Override
    public String travel() {
        return "Walking to destination";
    }
}

public class DriveStrategy implements TravelStrategy {
    @Override
    public String travel() {
        return "Driving to destination";
    }
}

public class FlyStrategy implements TravelStrategy {
    @Override
    public String travel() {
        return "Flying to destination";
    }
}

// Context
public class Traveler {
    private TravelStrategy strategy;

    public Traveler(TravelStrategy strategy) {
        this.strategy = strategy;
    }

    public void setStrategy(TravelStrategy strategy) {
        this.strategy = strategy;
    }

    public String travel() {
        return this.strategy.travel();
    }
}

5.3. Usage of the Strategy Pattern

// Client code
public class Main {
    public static void main(String[] args) {
        Traveler john = new Traveler(new WalkStrategy());
        System.out.println(john.travel());  // Output: Walking to destination

        john.setStrategy(new DriveStrategy());
        System.out.println(john.travel());  // Output: Driving to destination
    }
}

6. Advantages of Strategy Pattern

• Flexibility in swapping algorithms.
• Decoupling of algorithm from the client that uses it.
• Promotes Open/Closed principle.

7. Common Use Cases

• Different payment methods in e-commerce applications.
• Different compression techniques for files.
• Varying rendering techniques in graphics engines.

8. Conclusion

• The importance of understanding design patterns in software development.
• Encourage readers to experiment with the Strategy pattern and explore other design patterns.