Strategy Design Pattern Tutorial with Java Coding Example | Strategy Pattern Explained

Strategy is a behavioral design pattern that lets you define a family of algorithms, put each of them into a separate class, and make their objects interchangeable. Strategy pattern (also known as the policy pattern) is a software design pattern that enables an algorithm's behavior to be selected at runtime. The Strategy pattern consists of a number of related algorithms encapsulated in a driver class called the Context. Your client program can select one of these differing algorithms or in some cases the Context might select the best one for you. Strategy pattern are nothing but encapsulation of algorithms inside classes.

This pattern is useful when you want to decide on runtime which algorithm to be used. In Strategy pattern, we create objects which represent various strategies and a context object whose behavior varies as per its strategy object. The strategy object changes the executing algorithm of the context object. This is also example of open close design principle which make sure code is open for extension but closed for modification. Example, if you want to add new functionality, you can add it easily using the new code but without touching the existing code.

The Strategy pattern suggests that you take a class that does something specific and extract all of these algorithms into separate classes called strategies. The original class, called context, must have a field for storing a reference to one of the strategies. The context delegates the work to a linked strategy object instead of executing it on its own. The context isn’t responsible for selecting an appropriate algorithm for the job. Instead, the client passes the desired strategy to the context. Context works with all strategies because all strategies are derived from the same interface. In this setup, you can add new algorithms or modify existing ones without changing the code of the context or other strategies.

** Use of Strategy Design Pattern**
1. Use the Strategy pattern when you want to use different variants of an algorithm within an object and be able to switch from one algorithm to another during runtime.
2. Use the Strategy pattern when you want to use different variants of an algorithm within an object and be able to switch from one algorithm to another during runtime.
3. Use the Strategy when you have a lot of similar classes that only differ in the way they execute some behaviour.
4. Use Strategy pattern to isolate the business logic of a class from the implementation details of algorithms that may not be as important in the context of that logic.
5. Use Strategy pattern when your class has a massive conditional statement that switches between different variants of the same algorithm.

** Advantages of Strategy Design Pattern **
1 You can swap algorithms used inside an object at runtime.
2 Open close principle. Open for extension for closed for modification.
3 You can isolate the implementation details of an algorithm from the code that uses it.
4 You can replace inheritance with composition.

** Chapter Timestamps **
0:00 Welcome to Strategy Design Pattern
0:27 Recap of State Design Pattern
1:38 Introduction of Strategy Design Pattern
3:21 Example of Strategy Design Pattern
5:48 Java coding example of Strategy Design Pattern
10:37 Usage of Strategy Design Pattern
11:25 Advantages of Strategy Design Pattern
11:53 Summary of Strategy Design Pattern
12:29 Next video on Observer Design Pattern

#strategypattern #strategydesignpattern #softwaredesign

** Previous Video Links **
Previous Video (State Design Pattern): https://youtu.be/MAhsPU0bbhc

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