RTTI - Class.ForName( ) doesn't load my class

[Arthur Blair]

I am doing some examples from Bruce Eckel's Thinking of Java. But some of the code examples aren't behaving as expected. In the following example:

package rtti;
 
public class SweetShop {
    
    public static void main(String [] args) {
        System.out.println("Inside main");
        new Candy();
        System.out.println("After creating Candy");
        try {
[B]// Bruce reckons the following line should get the static initializer in the
// class Gum to run. But it doesn't.
            Class.forName("Gum"); [/B]
 
        } catch(ClassNotFoundException e) {
[B]// instead, this exception is caught:[/B]
            System.out.println("Couldn't find gum");
        }
        System.out.println("After Class.forName(\"Gum\")");
        new Cookie();
        System.out.println("After creating Cookie");
    }
}
 
class Candy {
    static { System.out.println("loading candy"); }
}
 
class Gum {
    static { System.out.println("loading gum"); }
}
 
class Cookie {
    static { System.out.println("loading cookie"); }
}

The output of the code is:

Inside main
loading candy
After creating Candy
[B]Couldn't find gum[/B]
After Class.forName("Gum")
loading cookie
After creating Cookie

But Bruce reckons is should be:

Inside main
loading candy
After creating Candy
[B]loading gum[/B]
After Class.forName("Gum")
loading cookie
After creating Cookie

because:

"Class.forName() returns a class reference, which is being ignored here. The call to forName() is being made for its side effect, which is to load the class Gum if it isn't already loaded. In the process of loading, Gum's static clause is executed."

So why doesn't the code behave as expected? I've copied it out exactly as the example in the book. I'm a little lost on this one.

Thoughts appreciated.

[Stuart Ash]

Maybe the gum got stuck


I have seen it pointed out once earlier as well that some code in Bruce's book wouldn't compile/run as expected. Maybe that's the case with this snippet as well. You wanna try sending this to Bruce himself at www.bruceeckel.com ??

[Jeff Albertson]

Read the API for Class.forName. Here's a relevant quote:

Given the fully qualified name for a class or interface (in the same
format returned by getName) this method attempts to locate, load, and link the
class or interface.

The emphasis is mine. Ahem.

And I hope you've already put a printStackTrace in that catch block to see
what went wrong instead of just sitting and waiting for BRUCE ALMIGHTLY
to come to the rescue...
[ November 17, 2005: Message edited by: Jeff Albrechtsen ]

[Arun Kumarr]

I suppose, the problem should be in your package declaration.

[Arthur Blair]

Thank you for the replies.

If I change the code to:

            Class.forName("rtti.Gum"); 

Everything works as bruce suggests.

Just for reference: A fully qualified name is the classname including the package.