Strategy Design pattern - Real Time Example [Travel]

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The Real-World Dilemma: How to Travel to the Airport?

Imagine you need to reach an airport or a destination city. Depending on various factors such as budget, time availability, and urgency, you have multiple ways to travel:

• Own Car: Highly flexible, convenient, but requires fuel and parking fees.
• Taxi / Cab: On-demand, comfortable, but can be expensive during peak hours.
• City Bus: Economical and cost-effective, but takes longer due to frequent stops.

If you write a program that handles travel booking using hardcoded if-else conditions, adding a new travel mode like a metro train or shuttle service requires modifying existing code. The Strategy Design Pattern solves this cleanly.

Encapsulating Travel Options as Strategies

The Strategy pattern defines a family of algorithms or business rules, encapsulates each one into a dedicated class, and makes them interchangeable from the client’s perspective:

• Strategy Interface: Defines a common method (e.g., gotoAirport(String source, String destination)) implemented by every mode of travel.
• Concrete Strategy Classes: Independent classes like CarStrategy, TaxiStrategy, and BusStrategy containing their respective journey details.
• Context Class: Represents the traveler or booking system that holds a reference to a travel strategy and delegates the actual travel behavior to it.

Key Architectural Benefits

By decoupling the travel method from the traveler context:

• Adheres to Open/Closed Principle: You can add newer transit modes (like high-speed rail) without changing any existing classes.
• Dynamic Runtime Decision: The traveler can dynamically evaluate prices or traffic conditions and pick the best strategy at runtime.
• Testability: Each travel strategy can be tested independently in isolation.

Related Design Pattern Tutorials to Watch Next

• Strategy Design Pattern Overview: A Beginner's Introduction
• Strategy Design Pattern in Action: Real-Time Payment Processing
• Strategy Design Pattern Explained: Real-Time File Compression Scenario

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Strategy Design pattern - Real Time Example [Travel]