wasNull()
Syntax:
boolean wasNull()
                throws SQLException
                                        Description:
Reports whether the last column read had a value of SQL NULL. Note that you must first call one of the getter methods on a column to try to read its value and then call the method wasNull to see if the value read was SQL NULL.
Returns:
true if the last column value read was SQL NULL and false otherwise
Throws:
SQLException - if a database access error occurs or this method is called on a closed result set
Reference:
For more information, reference JDBC documentation for: ResultSet.wasNull()