How to trap null return values from getters when using Method.invoke()?

Question

Hi,
I am using Method.invoke() to access getters in an Object. I need to know which getters return a value and which return null. However, irrespective of the actual return value, I am always getting non-null return value when using Method.invoke().
Unfortunately, the API documentation of Method.invoke() does not specify how it treats null return values.
Can someone help?
Thanks

Answer 1

What do you get as a result?I think I know what the problem is.
I tested this using following and it worked fine:
public class TestMethodInvoke {
public String getName() {
return null;
public static void main(String args[]) throws SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
Object o = new TestMethodInvoke();
Class cls = o.getClass();
Method m = cls.getMethod("getName", (Class[]) null);
Object result = m.invoke(o, (Object[])null);
if (result == null) {
System.err.println("OK: Return value was null as expected");
else {
System.err.println("FAILED: Return value was NOT null as expected");
However, when I use the same technique with an EJB 3.0 Entity class, the null return value is not returned. Instead, I get a String() object. Clearly, the problem is the the EJB 3.0 implementation (Glassfish/Toplink) which is manipulating the getters.
Regards
Dibyendu