I got the eroor imformation:
SQL4304N Java stored procedure or user-defined function "C532_064.MYADD", specific name "SQL030402190548299" could not load Java class "TestUDF/MyMath", reason code "1". SQLSTATE=42724

Following is my steps:

1. make a java file, package TestUDF, create a MYMath.class
create a pulic static method named :
public static void myAdd(double a,double b,double r);

2. make the .jar file by jbuilder

3. in db2 clp
3.1 connect to db2
3.2 CALL SQLJ.INSTALL_JAR('file:d:/TestUDF/TestUDF.jar' , 'TestUDF_jar');
3.3 CREATE FUNCTION myAdd(DOUBLE, DOUBLE) RETURNS DOUBLE FENCED LANGUAGE JAVA PARAMETER STYLE JAVA EXTERNAL NAME 'TestUDF.MyMath.myAdd' CALLED ON NULL INPUT DETERMINISTIC NO SQL NO EXTERNAL ACTION
3.4 use the function myAdd in sql

What's the problem?
Thanks.