Create an instance of a class from a string

Question

Is there a way to create an instance of a class based on the fact I know the name of the class at runtime  Basically I would have the name of the class in a string

User · Accepted Answer

Take a look at the Activator CreateInstance method

User · Answer

For instance  if you store values of various types in a database field  stored as string  and have another field with the type name  i e   String  bool  int  MyClass   then from that field data  you could  conceivably  create a class of any type using the above code  and populate it with the value from the first field  This of course depends on the type you are storing having a method to parse strings into the correct type  I ve used this many times to store user preference settings in a database

User · Answer

ReportClass report    ReportClass Activator CreateInstance Type GetType reportClass      why do u want to write a code like this  If you have a class  ReportClass  is available  you can instantiate it directly as shown below   ReportClass report   new ReportClass      The code ReportClass report    ReportClass Activator CreateInstance Type GetType reportClass    is used when you dont have the necessary class available  but you want to instantiate and or or invoke a method dynamically    I mean it is useful when u know the assembly but while writing the code you dont have the class ReportClass available

User · Answer

I ve used this method successfully   System Reflection Assembly GetExecutingAssembly   CreateInstance string className    You ll need to cast the returned object to your desired object type

User · Answer

Probably my question should have been more specific  I actually know a base class for the string so solved it by   ReportClass report    ReportClass Activator CreateInstance Type GetType reportClass      The Activator CreateInstance class has various methods to achieve the same thing in different ways  I could have cast it to an object but the above is of the most use to my situation

User · Answer

Probably my question should have been more specific  I actually know a base class for the string so solved it by   ReportClass report    ReportClass Activator CreateInstance Type GetType reportClass      The Activator CreateInstance class has various methods to achieve the same thing in different ways  I could have cast it to an object but the above is of the most use to my situation

User · Answer

I ve used this method successfully   System Reflection Assembly GetExecutingAssembly   CreateInstance string className    You ll need to cast the returned object to your desired object type

User · Answer

To create an instance of a class from another project in the solution  you can get the assembly indicated by the name of any class  for example BaseEntity  and create a new instance     var newClass   System Reflection Assembly GetAssembly typeof BaseEntity   CreateInstance  MyProject Entities User

User · Answer

Probably my question should have been more specific  I actually know a base class for the string so solved it by   ReportClass report    ReportClass Activator CreateInstance Type GetType reportClass      The Activator CreateInstance class has various methods to achieve the same thing in different ways  I could have cast it to an object but the above is of the most use to my situation

User · Answer

Its pretty simple  Assume that your classname is Car and the namespace is Vehicles  then pass the parameter as Vehicles Car which returns object of type Car  Like this you can create any instance of any class dynamically   public object GetInstance string strFullyQualifiedName                  Type t   Type GetType strFullyQualifiedName         return  Activator CreateInstance t                If your Fully Qualified Name ie  Vehicles Car in this case  is in another assembly  the Type GetType will be null  In such cases  you have loop through all assemblies and find the Type  For that you can use the below code  public object GetInstance string strFullyQualifiedName         Type type   Type GetType strFullyQualifiedName        if  type    null           return Activator CreateInstance type        foreach  var asm in AppDomain CurrentDomain GetAssemblies                    type   asm GetType strFullyQualifiedName            if  type    null               return Activator CreateInstance type               return null       Now if you want to call a parameterized constructor do the following   Activator CreateInstance t 17      Incase you are calling a constructor of int type   instead of  Activator CreateInstance t

User · Answer

ReportClass report    ReportClass Activator CreateInstance Type GetType reportClass      why do u want to write a code like this  If you have a class  ReportClass  is available  you can instantiate it directly as shown below   ReportClass report   new ReportClass      The code ReportClass report    ReportClass Activator CreateInstance Type GetType reportClass    is used when you dont have the necessary class available  but you want to instantiate and or or invoke a method dynamically    I mean it is useful when u know the assembly but while writing the code you dont have the class ReportClass available

User · Answer

For instance  if you store values of various types in a database field  stored as string  and have another field with the type name  i e   String  bool  int  MyClass   then from that field data  you could  conceivably  create a class of any type using the above code  and populate it with the value from the first field  This of course depends on the type you are storing having a method to parse strings into the correct type  I ve used this many times to store user preference settings in a database

User · Answer

To create an instance of a class from another project in the solution  you can get the assembly indicated by the name of any class  for example BaseEntity  and create a new instance     var newClass   System Reflection Assembly GetAssembly typeof BaseEntity   CreateInstance  MyProject Entities User

User · Answer

Probably my question should have been more specific  I actually know a base class for the string so solved it by   ReportClass report    ReportClass Activator CreateInstance Type GetType reportClass      The Activator CreateInstance class has various methods to achieve the same thing in different ways  I could have cast it to an object but the above is of the most use to my situation

User · Answer

I ve used this method successfully   System Reflection Assembly GetExecutingAssembly   CreateInstance string className    You ll need to cast the returned object to your desired object type

User · Answer

I know I m late to the game    but the solution you re looking for might be the combination of the above  and using an interface to define your objects publicly accessible aspects   Then  if all of your classes that would be generated this way implement that interface  you can just cast as the interface type and work with the resulting object

User · Answer

I ve used this method successfully   System Reflection Assembly GetExecutingAssembly   CreateInstance string className    You ll need to cast the returned object to your desired object type

User · Answer

I know I m late to the game    but the solution you re looking for might be the combination of the above  and using an interface to define your objects publicly accessible aspects   Then  if all of your classes that would be generated this way implement that interface  you can just cast as the interface type and work with the resulting object

User · Answer

Its pretty simple  Assume that your classname is Car and the namespace is Vehicles  then pass the parameter as Vehicles Car which returns object of type Car  Like this you can create any instance of any class dynamically   public object GetInstance string strFullyQualifiedName                  Type t   Type GetType strFullyQualifiedName         return  Activator CreateInstance t                If your Fully Qualified Name ie  Vehicles Car in this case  is in another assembly  the Type GetType will be null  In such cases  you have loop through all assemblies and find the Type  For that you can use the below code  public object GetInstance string strFullyQualifiedName         Type type   Type GetType strFullyQualifiedName        if  type    null           return Activator CreateInstance type        foreach  var asm in AppDomain CurrentDomain GetAssemblies                    type   asm GetType strFullyQualifiedName            if  type    null               return Activator CreateInstance type               return null       Now if you want to call a parameterized constructor do the following   Activator CreateInstance t 17      Incase you are calling a constructor of int type   instead of  Activator CreateInstance t

[c#] Create an instance of a class from a string

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