C#
MethodInfo.Invoke
Learn to invoke methods dynamically with MethodInfo.Invoke.
MethodInfo.Invoke
MethodInfo.Invoke(obj, args) calls a method via reflection. obj is the target instance (use null for static methods); args is the argument list as object[].
The return value comes back as object?; cast it to the real type. When the method name is known only at runtime (e.g. command handlers, plugin systems), the GetMethod + Invoke combination is used.
Static methods
To call static methods, pass null as the target to Invoke: mi.Invoke(null, args). For instance methods, the real instance must be provided; otherwise a TargetException is thrown.
This distinction comes from static members living at class level while instance members operate on a specific instance. Plugin systems typically call static entry points, while DI containers use instance methods.
Exercise Call a method with Invoke
In the Calculator class below, get the method with MethodInfo mi = typeof(Calculator).GetMethod("Square");. Call it with object result = mi.Invoke(calc, new object[] { 5 });. Print result with Console.WriteLine.
Show example solution
Get the method with MethodInfo mi = typeof(Calculator).GetMethod("Square");. Call it with object result = mi.Invoke(calc, new object[] { 5 });. Print with Console.WriteLine(result);.
Example solution:
using System;
using System.Reflection;
class Calculator
{
public int Square(int x) => x * x;
}
class Program
{
static void Main()
{
Calculator calc = new Calculator();
MethodInfo mi = typeof(Calculator).GetMethod("Square");
object result = mi.Invoke(calc, new object[] { 5 });
Console.WriteLine(result);
}
}
Test yourself
-
What is the first parameter of Invoke?
- The method name
- The parameter types
- The target instance (null for static)
- The return type
Show answer
The target instance (null for static) — Correct. The first parameter is the target instance; null for static methods.
-
Complete the Invoke call
object result = mi.____(obj, new object[] { 5 });
Show answer
object result = mi.Invoke(obj, new object[] { 5 });
-
Match the parameter to its meaning
- obj
- Target instance
- null
- For static
- new object[] {}
- Empty args
- new object[] { 5 }
- Single argument
Next lesson: PropertyInfo GetValue/SetValue
