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Very peculiar behaviour of Static method...

Chandra Bairi
Ranch Hand

Joined: Sep 12, 2003
Posts: 152
import java.lang.reflect.*;
public class Test
public static void main(String[] args)
Class c = Class.forName("Foo");
System.out.println("Loaded class: " + c);
Method m = c.getDeclaredMethod("getNum", null);
System.out.println("Got method: " + m);
Object o = m.invoke(null, null);
System.out.println("Output: " + o);
catch (Exception e)
class Foo
public static int getNum()
return 5;
consider the above code.
How could the output for this program come correctly 5. What could be reason when the getNum() method is called with null, null as parameters it is called perfectly why did this happen.

Ernest Friedman-Hill
author and iconoclast

Joined: Jul 08, 2003
Posts: 24189

Static methods don't need an instance on which to be invoked (hence there's no need for the first parameter of invoke() to be non-null) and your method has no arguments (hence there's no need for a non-null second parameter to invoke
The Javadoc for Method.invoke() specifically mentions that both of these parameters can be null when appropriate, and explains why. Check it out.

[Jess in Action][AskingGoodQuestions]
It is sorta covered in the JavaRanch Style Guide.
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