Strategy pattern is very useful for implementing a family of

algorithms. It is a behavioral design pattern.

With Strategy pattern we can select the algorithm at runtime. We can

use it to select the sorting strategy for data. We can use it to save

files in different formats like- .txt, .csv, .jpg etc.

In Strategy pattern we create an abstraction, which is an interface

through which clients interact with our system. Behind the

abstraction we create multiple implementation of same interface

with different algorithms.

For a client, at runtime we can vary the algorithm based on the type

of request we have received.

So we use Strategy pattern to hide the algorithm implementation

details from client.

In Java Collections.sort() method uses strategy design pattern.

https://refactoring.guru/design-patterns/strategy/java/example#:~:text=Strategy%20is%20a%20behavioral%20design,to%20the%20linked%20strategy%20object.

The Strategy Design Pattern is used in Java when you want to define a family of interchangeable algorithms or behaviors and make them available to a client code without the client needing to know the implementation details. This pattern is particularly useful in situations where you have multiple ways to perform a specific task and want to encapsulate each algorithm separately. Here are some scenarios where you might consider using the Strategy Design Pattern in Java:

Algorithms Variation:

When you have multiple algorithms or strategies that can be applied to solve a problem, you can encapsulate each algorithm in a separate strategy class. This allows you to easily switch between strategies based on requirements.

Run-Time Selection:

If you need to choose an algorithm at runtime based on dynamic conditions, the Strategy pattern enables you to switch strategies without modifying the client code.

Avoiding Conditional Statements:

If you find that your code has complex conditional statements that determine the behavior of an object, you can use the Strategy pattern to move the behavior into separate strategy classes, making the code cleaner and more maintainable.

Reducing Code Duplication:

If you have similar code appearing in multiple places to handle variations in behavior, you can centralize the behavior by using the Strategy pattern, reducing code duplication.

Testing and Maintenance:

The Strategy pattern promotes separation of concerns, making individual strategies easier to test and maintain. Changes to one strategy do not affect other strategies.

Decoupling:

The Strategy pattern promotes loose coupling between client code and the strategies. Clients only need to know about the strategy interface, not the concrete implementations.

Extensibility:

The Strategy pattern allows you to add new strategies without modifying existing code. This makes your codebase more extensible.

Examples of the Strategy pattern's usage in Java include sorting algorithms (such as bubble sort, quicksort, mergesort), payment gateways with different payment methods, text formatting with various formatting strategies, and more.

By using the Strategy Design Pattern, you can create flexible and maintainable code that adapts to different algorithms or behaviors without introducing complexities and dependencies in your client code.