implement singleton pattern on reflected class

[mangesh lele]

is there any way by which i can implement the singleton pattern on a reflected class?
i'm obtaining the class name as a string from a properties file and using Class.forName(String) to instantiate a Class object by that name. is there a way to call a static method implemented in this class (e.g. getInstance(), to implement the singleton pattern )?
rite now i'm using the work-around of calling the newInstance method of Class and then typecasting it to the class name, thus making my static
getInstance method redundant.

[Cindy Glass]

Try this:

import java.lang.reflect.*;
class Driver {

  public static void main(String args[]){
    try {
       Method me = Class.forName( args[0]).getDeclaredMethod("getInstance", null);
       Object obj = me.invoke(null, null);
       System.out.println(obj);
     }
     catch (ClassNotFoundException ex){}
     catch (NoSuchMethodException ex){}
     catch (IllegalAccessException ex){}
     catch (InvocationTargetException ex){}
   }
/*
}

Of course this presumes that the getInstance() method takes no parameters and is static.

[mangesh lele]

thanx cindy
i almost used the exact same code
one question though, pertaining to the following line in the javadocs:

)]javadocs

If the underlying method is static, the class that declared the method is initialized if it has not already been initialized.

wot does this mean? forgive me if i'm missing some basic funda

[Cindy Glass]

When a class is referenced, it is loaded by a classloader. Then it is linked which usually includes resolution of symbolic references in the class.
However the class itself is not initialized until specific events occur, such as invocation of certain reflective methods in the class library.

Initialization of a class or interface consists of invoking its static initializers (�2.11) and the initializers for static fields (�2.9.2) declared in the class.

Java Virtual Machine Specification 5.5 Initialization

[mangesh lele]

thanks again
i am soon gonna dive into the world of JVM