unable to see subreport from mainreport in runtime

[asumoto]

i am using ireport 1.2.5 and jdk1.5.0_08 and i am creating subreport and main report. however when i tried to view my report from my java program it give me error message like below:

 

"query.JRJdbcQueryExecuterÂÂ-ÂTheÂsuppliedÂjava.sql.ConnectionÂobjectÂisÂnull.Â"

 

my main report unable to display data in subreport. The same message appear in ireport compiler too if i set the "Connection/DataSource expression" become "Don't use connection or datasource" under subreport properties.

 

But if i set the "Connection/DataSource expression" become "Use connection expression" with

$P{REPORT_CONNECTION} i will be able to view the subreport's data from main report . But thats in ireport compiler.

 

Now i don't know how to implements it in my java program. Anyone can help me pls?

Where can i get the sample source code for viewing jasper file in java?