The Adapter Pattern

The Adapter Pattern


The Adapter Pattern is a tool for connecting incompatible classes or objects, enabling seamless communication between them.

This pattern promotes flexibility and adaptability, making it a valuable asset for C# developers.

Understanding the Adapter Pattern

The Adapter Pattern revolves around the concept of an adapter object that acts as a bridge between two incompatible interfaces.

It converts the communication style of one object to match the requirements of another, allowing them to work together seamlessly.

Benefits of the Adapter Pattern

The Adapter Pattern offers several advantages, including:

  • Flexibility: It enables the connection of incompatible classes or objects, promoting flexibility in design and implementation.
  • Adaptability: It facilitates the integration of new or legacy components without modifying their core functionality.
  • Encapsulation: It promotes encapsulation by hiding the complex adaptation process within the adapter object.
  • Maintainability: It improves maintainability by isolating adaptation logic from the original classes.
  • Code Reuse: It promotes code reuse by allowing for the reuse of existing components in new contexts.
  • Type Compatibility: It enables the connection of objects with differing interfaces, enhancing type compatibility.

Types of Adapter Patterns

The Adapter Pattern encompasses several variations, each with its specific characteristics:

  • Object Adapter: This pattern uses inheritance to connect incompatible classes.
  • Class Adapter: This pattern uses composition to connect incompatible classes.
  • Proxy Adapter: This pattern provides a controlled way to access an object, such as hiding its implementation or providing additional security.

Implementing the Adapter Pattern in C#

To illustrate the implementation of the Adapter Pattern in C#, consider a simplified scenario of adapting a legacy text file reader to a new format:

Legacy Text File Reader:

The legacy text file reader reads and writes text files in an outdated format.

public class LegacyTextFileReader
    public void ReadFile(string filepath)
        // Read text file in legacy format

    public void WriteFile(string filepath, string data)
        // Write data to text file in legacy format

New File Format Adapter:

The new file format adapter translates between the legacy format and the new format.

Using the Adapter Pattern:

To use the adapter pattern for reading and writing data in a new format:

public class NewFileFormatAdapter
    private LegacyTextFileReader reader;
    private NewFileFormatWriter writer;

    public NewFileFormatAdapter(string filepath)
        reader = new LegacyTextFileReader();
        writer = new NewFileFormatWriter(filepath);

    public void ReadData()
        string data = reader.ReadFile("legacyFile.txt");

    public void WriteData(string data)
        string newFormatData = Translator.Translate(data);
        writer.WriteFile("newFile.txt", newFormatData);

This example demonstrates a basic implementation of the Adapter Pattern in C# for adapting legacy file reading and writing to a new format.

The adapter pattern can be extended to handle more complex adaptation scenarios.


The Adapter Pattern is a valuable tool for connecting incompatible classes or objects and promoting flexibility, adaptability, and maintainability in C# code.

It enables seamless interaction between diverse components, enhancing the reusability and adaptability of software systems.

By leveraging the Adapter Pattern, developers can create robust, flexible, and maintainable applications.


Hi, my name is Stephen Finchett. I have been a software engineer for over 30 years and worked on complex, business critical, multi-user systems for all of my career. For the last 15 years, I have been concentrating on web based solutions using the Microsoft Stack including ASP.Net, C#, TypeScript, SQL Server and running everything at scale within Kubernetes.