Create an Instance of a Class from a String

Create an instance of a class from a string

Take a look at the Activator.CreateInstance method.

C# Instantiate a Class from String name

This technical called Reflection, that means call an instance from string.
My calling class will be

public class Class1
{
    public string Property { get; set; } = "I'm class1";
    public void DoSpecialThings()
    {
        Console.WriteLine("Class1 does special things");
    }
}

Next I create an instance in a static function, should put your all classes in a same namespace to easy control

    public static dynamic GetClassFromString(string className)
    {
        var classAddress = $"NetCoreScripts.{className}";
        Type type = GetType(classAddress);

        // Check whether the class is existed?
        if (type == null)
            return null;

        // Then create an instance
        object instance = Activator.CreateInstance(type);

        return instance;
    }

And a GetType method

    public static Type GetType(string strFullyQualifiedName)
    {
        Type type = Type.GetType(strFullyQualifiedName);
        if (type != null)
            return type;
        foreach (var asm in AppDomain.CurrentDomain.GetAssemblies())
        {
            type = asm.GetType(strFullyQualifiedName);
            if (type != null)
                return type;
        }
        return null;
    }

I use dynamic type to implement quickly, basically you can use interface for explicit coding.

    static async Task Main(string[] args)
    {
        dynamic instance = GetClassFromString("Class1");

        Console.WriteLine(instance.GetType().FullName); //NetCoreScripts.Class1

        Console.WriteLine(instance.GetType().Name); //Class1

        Console.WriteLine(instance.Property); //I'm class1

        instance.Property = "Class1 has been changed";
        Console.WriteLine(instance.Property); //Class1 has been changed

        instance.DoSpecialThings(); // Class1 does special things
    }

Create instance of class and call method from string

// Find a type you want to instantiate: you need to know the assembly it's in for it, we assume that all is is one assembly for simplicity
// You should be careful, because ClassName should be full name, which means it should include all the namespaces, like "ConsoleApplication.MyClass"
// Not just "MyClass"
Type type = Assembly.GetExecutingAssembly().GetType(ClassName);
// Create an instance of the type
object instance = Activator.CreateInstance(type);
// Get MethodInfo, reflection class that is responsible for storing all relevant information about one method that type defines
MethodInfo method = type.GetMethod(MethodName);
// I've assumed that method we want to call is declared like this
// public void MyMethod() { ... }
// So we pass an instance to call it on and empty parameter list
method.Invoke(instance, new object[0]);

Create object instance of a class having its name in string variable

Having the class name in string is not enough to be able to create its instance.
As a matter of fact you will need full namespace including class name to create an object.

Assuming you have the following:

string className = "MyClass";
string namespaceName = "MyNamespace.MyInternalNamespace";

Than you you can create an instance of that class, the object of class MyNamespace.MyInternalNamespace.MyClass using either of the following techniques:

var myObj = Activator.CreateInstance(namespaceName, className);

or this:

var myObj = Activator.CreateInstance(Type.GetType(namespaceName + "." + className));

Hope this helps, please let me know if not.

How to create an instance of a class from a String in Swift

You can try this:

func classFromString(_ className: String) -> AnyClass! {

    /// get namespace
    let namespace = Bundle.main.infoDictionary!["CFBundleExecutable"] as! String

    /// get 'anyClass' with classname and namespace 
    let cls: AnyClass = NSClassFromString("\(namespace).\(className)")!

    // return AnyClass!
    return cls
}

use the func like this:

class customClass: UITableView {}   

let myclass = classFromString("customClass") as! UITableView.Type
let instance = myclass.init()

Creating an instance from String in Java

Class c= Class.forName(className);
return c.getDeclaredConstructor().newInstance();//assuming you aren't worried about constructor .

• javadoc

For invoking constructor with argument

 public static Object createObject(Constructor constructor,
      Object[] arguments) {

    System.out.println("Constructor: " + constructor.toString());
    Object object = null;

    try {
      object = constructor.newInstance(arguments);
      System.out.println("Object: " + object.toString());
      return object;
    } catch (InstantiationException e) {
      //handle it
    } catch (IllegalAccessException e) {
      //handle it
    } catch (IllegalArgumentException e) {
      //handle it
    } catch (InvocationTargetException e) {
      //handle it
    }
    return object;
  }
}

have a look

Create class instance from string in dartlang

For passing arguments dynamically to the constructor you can use newInstance method of ClassMirror.

For example

  MirrorSystem mirrors = currentMirrorSystem();
  ClassMirror classMirror = mirrors.findLibrary(Symbol.empty).declarations[new Symbol('Opacity')];
  print(classMirror);
  var arguments = {'a': 'a', 'b': 'b', 'c': 'c'}.map((key, value) {
    return MapEntry(Symbol(key), value);
  });
  var op = classMirror.newInstance(Symbol.empty, [], arguments);
  Opacity opacity = op.reflectee;
  print("opacity.a: ${opacity.a}");
  print("opacity.b: ${opacity.b}");
  print("opacity.c: ${opacity.c}");

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