Can not find subclass method

[samanesh]

This code gives a compile error (Cannot find symbol method k() at sub.k())
and i need to know why this is. it does not give an error if MainClass has the exact same function k() (return type and arguments)
but i dont want that. is there any way to make this work?

public class MainClass {	
	public static void main(String[] args){
		MainClass sub = new SubClass();
		sub.k();
	}
}

class SubClass extends MainClass {
	void k(){
		System.out.println("1,2,3, test, test");
	}
}

[Squiffy]

The trouble is, once you've used a MainClass reference to refer to your SubClass, you're stuck with only being able to call methods that exist in that particular form in MainClass.

You have two choices:

1. Use a reference of type SubClass (this makes sense!)

public class MainClass {
public static void main(String[] args){
SubClass sub = new SubClass();
sub.k();
}
}

class SubClass extends MainClass {
void k(){
System.out.println("1,2,3, test, test");
}
}



2. Downcast the MainClass variable to SubClass -- since it does, after all, refer to an object of type SubClass. But this is a bit crazy.

public class MainClass {
public static void main(String[] args){
MainClass sub = new SubClass();
((SubClass)sub).k();
}
}

class SubClass extends MainClass {
void k(){
System.out.println("1,2,3, test, test");
}
}

[Fubarable]

Better option: simply give MainClass a public void k() method. Why is this not a viable option if you want to treat MainClass variables as if they have this method?

[samanesh]

for my program the easiest to do will be to add an empty method, I knew this worked but i wanted to know if i could avoid it. thank you for the help.

[Fubarable]

for my program the easiest to do will be to add an empty method, I knew this worked but i wanted to know if i could avoid it. thank you for the help.

If you are going to exepct MainClass variables to call a method, then the method needs to be accessible to the MainClass. Consider making MainClass abstract and the k method just a method definition.