Generic interfaces in C Sharp (C#) - Mini Project: Build & Apply

Using Generic Interfaces in C#

📖 Scenario: You are building a simple system to store and display items of different types. You want to use a generic interface to handle items in a flexible way.

🎯 Goal: Create a generic interface called IItemHolder<T> with a method to get the item. Then implement this interface in a class and display the stored item.

📋 What You'll Learn

Create a generic interface IItemHolder<T> with a method T GetItem().

Create a class ItemHolder<T> that implements IItemHolder<T>.

Add a constructor to ItemHolder<T> to store an item of type T.

Implement the GetItem() method to return the stored item.

Create an instance of ItemHolder<string> with the value "Hello World".

Print the item returned by GetItem().

💡 Why This Matters

🌍 Real World

Generic interfaces let you write flexible code that works with many types without repeating yourself. For example, you can create containers or handlers for different data types easily.

💼 Career

Understanding generic interfaces is important for writing reusable and maintainable code in professional C# development, especially in libraries and frameworks.

1

Create the generic interface

Create a generic interface called IItemHolder<T> with a method T GetItem().

C Sharp (C#)

// Your code here

Need a hint?

Use the interface keyword and add a generic type parameter <T>. Define a method T GetItem() inside.

2

Create the class that implements the interface

Create a class called ItemHolder<T> that implements the interface IItemHolder<T>. Add a private field item of type T and a constructor that takes a parameter item of type T and stores it.

C Sharp (C#)

public interface IItemHolder
{
    T GetItem();
}

// Your code here

Need a hint?

Use class ItemHolder<T> : IItemHolder<T>. Add a private field item and a constructor to set it.

3

Create an instance and call the method

Create an instance of ItemHolder<string> called holder with the value "Hello World". Then call holder.GetItem() and store the result in a variable called result.

C Sharp (C#)

public interface IItemHolder
{
    T GetItem();
}

public class ItemHolder : IItemHolder
{
    private T item;

    public ItemHolder(T item)
    {
        this.item = item;
    }

    public T GetItem()
    {
        return item;
    }
}

// Your code here

Need a hint?

Create holder using new ItemHolder<string>("Hello World"). Call GetItem() and save to result.

4

Print the result

Write a line to print the variable result to the console.

C Sharp (C#)

public interface IItemHolder
{
    T GetItem();
}

public class ItemHolder : IItemHolder
{
    private T item;

    public ItemHolder(T item)
    {
        this.item = item;
    }

    public T GetItem()
    {
        return item;
    }
}

var holder = new ItemHolder("Hello World");
var result = holder.GetItem();

// Your code here

Need a hint?

Use Console.WriteLine(result); inside a Main method to print the value.