Help a new person with DataSources

[2004 IR Help]

By: exabrial - exabrial

Help a new person with DataSources

2005-01-22 21:42

I must be completely retarded. I have spent 3 hours trying how to figure out to do this.

 

I designed a report with IReport. In I report, there is a field called "Cookie" that's a string. I attempt to display the entire contents field by putting, "$F{Cookie}" in the report.

 

Am I good so far?

 

Next, I want to fill that field from a set(hashset to be exact).

 

<code>

HashSet fields = new HashSet();

fields.add("Chocolate");

fields.add("Peanut Butter");

fields.add("Oatmeal");

JRMapCollectionDataSource data = new JRMapCollectionDataSource(fields);

</code>

 

Now what do i do? I have this code, but it doesn't work. It throws a ClassCastException.

 

<code>

jasperPrint = jasperFillManager.fillReport(jasperReport,parameters, data);

</code>

 

Like i said, i must be stupid. Everyone else on the board seemed to figure this out... Thank you for any help.

 

-Jon

 

 

 

 

By: David Lim - aberrant80

RE: Help a new person with DataSources

2005-01-24 01:41

You did two things wrong:

 

1) It's a JRMapCollectionDataSource. The word "Map" in the class name means a Set won't do.

 

2) A data source represents a collection a data that should be in a structure that resembles a table. Basically, for this class to work, your data source needs to be a map of maps. The inner maps are all keyed by the field names.

 

In you example, it should've been a map of 3 maps, where each of the inner map has one entry keyed by "Cookie".

 

Hope I'm clear enough.