7.3. Previewing Reports

To preview a report select the Preview tab in the Design Editor. Before the report preview is shown in the viewer, it's automatically compiled and then filled using data from the selected data source. If the report cannot be compiled then the Preview Viewer becomes disabled and displays an error message.

After a successful report execution the report viewer displays the first page (or a previously selected page) of the resulted document. The current page as well as the total number of report pages are shown in the viewer's status bar. Document pages can be navigated using the viewer's toolbar.

The data source that is used to fill the report can be changed at any time. This allows to quickly test the report using different data sources.

Figure 7.3. Preview viewer

Preview viewer


JasperAssistant does not provide a dialog to input report parameters. To test report parameters, you must provide them with default values.

The Preview Viewer can consume a significant amount of memory, depending on the size of the data source. It is recommended that you change the default Eclipse memory settings and increase the available memory to at least 256M. This is done by starting Eclipse with additional parameters as follows:

eclipse -vmargs -Xms256m -Xmx256m


The output of the report produced during its execution can be viewed using the Console View. For more information please see Section 5.8, “Console View”.


Errors produced by a report execution can be viewed using the Error Log view. For more information please see Section 5.9, “Error Log”.