Pie chart with datasource collection would not diaply key expression label

[yanivm]

Hey,

i have created a JasperPring object with a JRDataSource which holds a collection of the following Object

public BeanWithList(String countries,  List<String> cities, List<Integer> population)

I wish to create on the "Detail band" a list of pieChart for each county , that would hold cities in that county and its population.

On IReport , Fields I created the following : countries , cities, population

I created a new dataset with the fileds city and population_per_city

and created a pie chart with a

key expression of   $F{city}

key expression of   $F{population_per_city}

now here is the problem , i can only set one datasource ,

I set new net.sf.jasperreports.engine.data.JRBeanCollectionDataSource($F{population})

but this only means that i can get information for the $F{population_per_city} variable , but the variable $F{city} is blank or equal to the population since they take the same value ...

how can i solve this ...