Passing numerical variables to and from a Java class

Question

I'm trying to do something that seems like it should be fairly simple, but apparently it isn't. I'm new to Java and JDBC, so I'm hoping that I'm missing something fundamental and fairly basic.
Basically, I want to pass a set of (number) variables to a Java class from a PL/SQL Procedure, and get back a series of numbers based on calculations to the first set of numbers. (In my real world project, I have to perform a series of matrix calculations to determine regression parameters for two sets of data, but we'll keep this simple.) However, I can find nothing that tells me how to do this, and I'm receiving a series of errors when I attempt it.
For example, let's say I want to send in two decimal numbers, a and b, and receive back the sum s, the difference d, the product p and the quotient q. So, the java class would be:
* MathEx.java
class MathEx {
public static void main(double a, double b, double sum, double diff, double prod, double quo) {
sum = a + b;
diff = a - b;
prod = a * b;
quo = a / b;
Fairly simple, right? It compiles fine using "javac MathEx.java", and then I load the class into the database:
loadjava -u steve/steve MathEx.class
Everything works great. Now, I create a wrapper Procedure. This is where the problem comes in. How do I declare the incoming and outgoing parameters in the Procedure? No matter what I try, I get " the declaration of "MathEx.main([whatever])" is incomplete or malformed"
The procedure I'm trying is:
create or replace procedure Call_MathEx
a NUMBER,
b NUMBER,
s NUMBER,
d NUMBER,
p NUMBER,
q NUMBER
AS
language JAVA
name 'MathEx.main(oracle.sql.NUMBER,oracle.sql.NUMBER,
oracle.sql.NUMBER,oracle.sql.NUMBER,oracle.sql.NUMBER,oracle.sql.NUMBER,)';
I've tried the following values for possible variable types in the "name 'MathEx.main(" statement:
oracle.sql.NUMBER
java.lang.Number
java.lang.Double
java.Math.BigDecimal
The only thing I can get to work is if I just use "java.lang.string[]" and send everything at once, then use parseDouble() to read the parameters inside the Java class. However, that makes it impossible to then read the new values of the sum, difference, product and quotient in the calling procedure, since the variable retain the same value as before the call to the Java class.
Any help is greatly appreciated.

Answer 1

Java Stored Procedures Developers Guide (part of the docs and here on OTN) would probably help.
I suspect you need:
create or replace procedure Call_MathEx
a IN NUMBER,
b IN NUMBER,
s OUT NUMBER,
d OUT NUMBER,
p OUT NUMBER,
q OUT NUMBER
AS
language JAVA
name 'MathEx.main(oracle.sql.NUMBER,oracle.sql.NUMBER,
oracle.sql.NUMBER,oracle.sql.NUMBER,oracle.sql.NUMBER,oracle.sql.NUMBER,)';
Not sure, I always let JDeveloper handle it for me :)