C# Generic

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C# allows you to define generic classes, interfaces, abstract classes, fields, methods, static methods, properties, events, delegates, and operators using the type parameter and without the specific data type. A type parameter is a placeholder for a particular type specified when creating an instance of the generic type.

A generic type is declared by specifying a type parameter in an angle brackets after a type name, e.g. TypeName where T is a type parameter.

Generic Class

class DataStore<T>
{
    public T Data { get; set; }
}

Above, the DataStore is a generic class. T is called type parameter, which can be used as a type of fields, properties, method parameters, return types, and delegates in the DataStore class. For example, Data is generic property because we have used a type parameter T as its type instead of the specific data type.

It is not required to use T as a type parameter. You can give any name to a type parameter.

Instantiating Generic Class

DataStore<string> store = new DataStore<string>();

DataStore<string> store = new DataStore<string>();
store.Data = "Hello World!";
//store.Data = 123; //compile-time error

You can specify the different data types for different objects

DataStore<string> strStore = new DataStore<string>();
strStore.Data = "Hello World!";
//strStore.Data = 123; // compile-time error

DataStore<int> intStore = new DataStore<int>();
intStore.Data = 100;
//intStore.Data = "Hello World!"; // compile-time error

A generic class increases the reusability. The more type parameters mean more reusable it becomes. However, too much generalization makes code difficult to understand and maintain.