Generic methods have type parameters. These parameters can be used in the method header or body. An open method has type parameters, which are nonspecific. A closed method has type arguments, where specific types are substituted for type parameters. For a generic method, the type parameters are listed after the function name. The type parameter list is enclosed in angle brackets. Each parameter is comma-delimited.

Here is a sample generic method:

using System;

namespace Donis.CSharpBook {

    public class Starter {
        public static void Main() {
            ZClass.MethodA<int>(20);
        }
    }

    public class ZClass{
        public static void MethodA<T>(T param) {
            Console.WriteLine(param.GetType().ToString());
        }
    }
}

When calling a generic method, insert the type arguments to replace type parameters. Inferring a type is an alternate syntax to calling a generic method, where the type arguments are inferred from the actual method parameters. The type argument then can be omitted with type inference. Basically, the generic method is called in the same manner as a non-generic method. The benefit is ease of use. However, type inference can disguise the true nature of the call, which could be relevant to someone maintaining or debugging an application.

In the previous code, ZClass.MethodA is a generic method. The following statement calls MethodA using type inference:

ZClass.MethodA(20);

Here is the syntax of a generic method, where both the parameters and return type can be generic:

attributes accessibility modifiers returntype identifier<type_parameterlist>
    (parameterlist) where type_parameter : constraintlist
    { method body }

using System;

namespace Donis.CSharpBook {

    public class Starter {
        public static void Main() {
            ZClass<int> obj = new ZClass<int>();
            obj.MethodA();
        }
    }

    class ZClass<T> {
        public T MethodA() {
           T var = default(T);
           Console.WriteLine(this.GetType().ToString());
           return var;
        }
    }
}