1.38.1. Define the interface: MyInterface.cs #

Interface usage interface keyword declaration, which is similar to a class declaration. The interface declaration defaults to public . Here is an example of an interface declaration:

interface IMyInterface
{
    void MethodToImplement();
}

The above code defines the interface IMyInterface . Usually the interface command begins with the letter I, and there is only one method forthis interface MethodToImplement() , no parameters and return values, but of course we can set parameters and return values as required.

It is worth noting that there is no concrete implementation of this method.

1.38.2. Implement the above interfaces： InterfaceImplementer.cs #

Example

using System;
interface IMyInterface
{
        // Interface Members
    void MethodToImplement();
}
class InterfaceImplementer : IMyInterface
{
    static void Main()
    {
        InterfaceImplementer iImp = new InterfaceImplementer();
        iImp.MethodToImplement();
    }
    public void MethodToImplement()
    {
        Console.WriteLine("MethodToImplement() called.");
    }
}

InterfaceImplementer class implements the IMyInterface interface, the implementation of the interface is similar to the inheritance syntax of the class:

class InterfaceImplementer : IMyInterface

After inheriting the interface, we need to implement the method of the interface MethodToImplement() method name must match the method name defined by the interface

1.38.3. Interface inheritance: InterfaceInheritance.cs #

The following example defines two interfaces IMyInterface and IParentInterface .

If one interface inherits from other interfaces, then the implementation class or structure needs to implement the members of all interfaces.

The following example IMyInterface inherited IParentInterface interface, so the interface implementation class must implement the MethodToImplement() and ParentInterfaceMethod() methods:

Example

using System;
interface IParentInterface
{
    void ParentInterfaceMethod();
}
interface IMyInterface : IParentInterface
{
    void MethodToImplement();
}
class InterfaceImplementer : IMyInterface
{
    static void Main()
    {
        InterfaceImplementer iImp = new InterfaceImplementer();
        iImp.MethodToImplement();
        iImp.ParentInterfaceMethod();
    }
    public void MethodToImplement()
    {
        Console.WriteLine("MethodToImplement() called.");
    }
    public void ParentInterfaceMethod()
    {
        Console.WriteLine("ParentInterfaceMethod() called.");
    }
}

The output result of the instance is:

MethodToImplement() called.
ParentInterfaceMethod() called.