iReport Ultimate Guide - Nimsoft Library

iReport Ultimate GuideAll the other properties can be left as they are; in particular, we don’t want to set a default value expression. By dragging theparameter into the Title band we can create a textfield to display the REPORT_TITLE parameter (shown in Figure 6-10).Figure 6-10Design panel with the REPORT_PARAMETER displayed in the title bandThis example report is very simple. We just want to focus our attention on how to display the parameter.To set the value of the REPORT_TITLE parameter in our application, modify the code of the previous source code example byadding:...HashMap hm = new HashMap();hm.put(“REPORT_TITLE”,”This is the title of the report”);...JasperPrint print = JasperFillManager.fillReport(fileName,hm,new JREmptyDataSource());...We have included a value for the REPORT_TITLE parameter in the parameter map. You do not need to pass a value for all theparameters. If you don’t provide a value for a certain parameter, UR will assign the value of Default ValueExpression to the parameter with the empty expression evaluated as null.Printing the report, iReport includes the String This is the title of the report in the Title band. In this case we justused a simple String. However, it is possible to pass much more complex objects as parameters, such as an image(java.awt.Image) or a data source instance configured to provide a specified subreport with data. The most important thingto remember is that the object passed in the map as the value for a certain parameter must have the same type (or at least be asuper class) of the type of the parameter in the report. Otherwise, iReport fails to generate the report, returning aClassCastException error. This is actually pretty obvious; you cannot, for example, assign the value of ajava.util.Date to a a parameter declared as an Integer.106