Call subclass variables from superclass

[John Lockheart]

I understand how to call superclass variables from a subclass. But what if I wanted to call subclass variables from the superclass. Or even sub subclass variables (a subclass inside a subclass of the superclass) from a superclass. I want to reach down the Hierarchy for variables as opposed to reaching up (like when using super). How do I do that? Or is it not possible because the super class can't inherit any of the subclass variables? I'll use examples from the program i've been working on. I know there's supposed to be more code but I just slapped that together.

    
abstract class Threat {
 
public changeVariable(){
 //modify variables in Malware class (extends Threat)
 //modify variables in Virus class (extends Malware)
}
 
public useVariablesForIfCase(){
 
 //use variables in Malware class for if conditions (extends Threat)
 //use variables in Virus class for if conditions (extends Threat)
 
}
 
}
 
abstract class Malware extends Threat{
 
  //assign some variables
 
}
 
class Virus extends Malware{
  
    assign some variables
 
}

[mohsen fakhari]

Hi
When you modify a variable of Threat from Virus,in fact you modify a variable of Virus itself,because Virus instances do have all variables of Threat.
But speaking about a Threat instance,Virus is completely stranger whom it knows nothing about.

[marc weber]

On the surface, that's a reasonable question. But consider these issues:

How would a superclass "know" what subclasses are extending it?

If it did know, how might a superclass decide which of these subclasses to try to get a value from?

More fundamentally, what could a superclass do with a value from a subclass? In other words, why would the state of a subclass be of any concern to a superclass?

[Garrett Rowe]

If these behaviors should be common to all sub classes, then you can move the behaviors there:

abstract class Threat {
 
   public changeVariable(){
     setState(newState);
   }
   
   public useVariablesForIfCase(){
      if (getBooleanValue()) {
         //...
      }
   }
 
   public abstract boolean getBooleanValue();
   public abstract void setState(Object newState);
   
}

This forces the subclasses to implement behavior that can be used by the superclass. Polymorphism.
[ January 27, 2007: Message edited by: Garrett Rowe ]