Java, convert(cast) Serializable objects to other objects

Question

I'm using Session.save() method (in Hibernate) to persist my entity objects which returns an object of type java.io.Serializable.

The returned value is the generated primary key for the entity.

The generated primary key is of type long (or bigint).

The question is that: How can I convert or cast the returned value to long?

Serializable result = session.save(myEntityObject);

//This line of code fails. 
long r = (long)result;

Answer 1

Try casting the result (since it's not a primitive) to Long instead of long.

Long r = (Long)result;
long longValue = r.longValue();

Answer 2

Try

long r = Long.valueOf(String.valueOf(result)).longValue();

Answer 3

Have you tried using a debugger and breaking at that line to see what "result" is exactly?

It could be BigDecimal or Long or ...

Alternatively, cant you just call the primary key getter method on the object - I'd have hoped it would be set by that point.

HTH, Chris