Dynamic Cast

[Davide Gesino]

Hi, I have to write a program that reads a certain number of classes, whose name is known at runtime and launch them as a thread. I suppose that each of these classes implements the "Runnable" interface.
If the name was known at compile time I would write:
...
MyClass1 anInstance1=new MyClass1();
Thread t1=new Thread(anInstance1);
MyClass2 anInstance2=new MyClass2();
Thread t2=new Thread(anInstance2);
...
and so on.

In my case I use the reflection methods an I write:

public static void main(String[] args){

String externClassName = new String();

if (args.length>0) {
externClassName=args[0];
}

try {

Class inputClass= Class.forName(externClassName);
Object doOrDie=inputClass.newInstance();
if(inputClass.isInstance(doOrDie)){

Thread t1= new Thread((inputClass)doOrDie); /* this cast doesn't work! */
t1.start();
}
...
...
I've seen that if "inputClass" was known at compile time the cast would work and the code compile.
Can Someone help me?

William

[Kedar Bhawarthi]

note your code...

 
MyClass1 anInstance1=new MyClass1();
Thread t1=new Thread(anInstance1);

object anInstance1 is implicitly casted to Runnable
hence you are suppose to write like...

if(doOrDie instanceOf Runnable )
{
Thread t1= new Thread((Runnable)doOrDie);
t1.start();
}

this will work because Threads constructor takes
Runnable ref as argument.

[Dirk Schreckmann]

Moving this to the Intermediate forum...