dinamic classloader?

[Novello]

Hello,

My program needs to create a class, see code below to understand ;-)

/**
* Loads system's class and execute it
*/
private static void loadSystem(String systemName,String symbol) {

// wrong code:
systemName system = new systemName(symbol);

}

the first param is systemName, the name of the class to create.
I cannot create it such as "systemName system = new sytemName(symbol)"
because systemName is a String and not a Class.

How can I solve this problem?

If something is not clear please ask, I will explain better

thank you

 

[Andrew Thompson]

Hello,

Please refrain from multi-posting.

 

[John Currier]

There's currently a discussion titled "Defining a constructor in an
Interface" in this newsgroup...the initial post should give you a
starting point.

John
http://schemaspy.sourceforge.net

 

[Chris Smith]

/**
* Loads system's class and execute it
*/
private static void loadSystem(String systemName,String symbol) {

// wrong code:
systemName system = new systemName(symbol);

}

the first param is systemName, the name of the class to create.
I cannot create it such as "systemName system = new sytemName(symbol)"
because systemName is a String and not a Class.

Google for "reflection". The basic pattern looks like this:

private static void loadSystem(String systemName,String symbol)
throws ...
{
Class c = Class.forName(systemName);
Constructor ctor = c.getConstructor(String.class);
Object system = ctor.newInstance(symbol);
}

(* This is 1.5 code. In 1.4 and previous versions, you'll need to
explicitly instantiate the Class[] in the getConstructor call, and the
Object[] in the newInstance call. 1.5 makes this cleaner. See the API
docs for the appropriate signatures for all of those methods.)

(** I've left out exception handling. When using reflection, there are
a gazillion things that might go wrong, so you should handle the
exceptions.)

Note that the reference you get back is of type Object, not of the
specific class you loaded. That's actually the best you can do; the
compiler obviously doesn't know what methods or fields are available for
that dynamic class. To use the object, you will need to do one of two
things: cast the object to an interface or superclass type that declares
the operations you need, or use reflection again to find the methods and
fields and to access them.

--
www.designacourse.com
The Easiest Way To Train Anyone... Anywhere.

Chris Smith - Lead Software Developer/Technical Trainer
MindIQ Corporation