arpanadn

Hi , I am new to Jasper Reports and i am trying to generate a bar chart with data coming from my data source but am getting stuck at a place. I am getting exception which i am not able to resolve. Cant figure out where am i going wrong . Can someone pls help. Exception in thread "main" java.lang.NullPointerException at net.sf.jasperreports.charts.fill.JRFillCategoryDataset.customIncrement(JRFillCategoryDataset.java:136) at net.sf.jasperreports.engine.fill.JRFillElementDataset.increment(JRFillElementDataset.java:134) Heres the java file. public class JasperReportsIntro { public static void main(String[] args) { JasperReport jasperReport; JasperPrint jasperPrint; try { jasperReport = JasperCompileManager.compileReport("/home/arpana/work/bccms/src/com/bc/reports/rep/jasperreports_demo.jrxml"); String columnNames[]={"FIELD1","VALUE"}; ArrayList arrayList = new ArrayList<ArrayList<Double>>(); List<Double> dataArray = new ArrayList<Double>(); dataArray.add(0.0); dataArray.add(1.0); arrayList.add(dataArray); List<Double> dataArray1 = new ArrayList<Double>(); dataArray1.add(2.0); dataArray1.add(3.0); arrayList.add(dataArray1); jasperPrint = JasperFillManager.fillReport(jasperReport, new HashMap(), new JRTableModelDataSource(new DataSource(columnNames, arrayList))); JasperExportManager.exportReportToPdfFile(jasperPrint, "/home/arpana/bar_report.pdf"); System.out.println("Successfully exported to PDF"); } catch (JRException e) { e.printStackTrace(); } } } Heres the jrxml file : <?xml version="1.0"?> <!DOCTYPE jasperReport PUBLIC "-//JasperReports//DTD Report Design//EN" "http://jasperreports.sourceforge.net/dtds/jasperreport.dtd"> <jasperReport name="Simple_Report"> <parameter name="VALUE_HEADER_P" isForPrompting="false" class="java.lang.String"/> <field name="FIELD1" class="java.lang.Double"> </field> <field name="VALUE" class="java.lang.Double"> </field> <variable name="SumFirstGroup" class="java.lang.Double"> <variableExpression><![CDATA[$F{VALUE}]]></variableExpression> </variable> <group name="FirstGroup" isStartNewColumn="false" isReprintHeaderOnEachPage="false" minHeightToStartNewPage="25"> <groupExpression><![CDATA[$F{FIELD1}]]></groupExpression> </group> <detail> <band height="120"> <staticText> <reportElement x="80" y="0" width="200" height="20"/> <text><![CDATA[Hello World!]]></text> </staticText> <barChart> <chart evaluationTime="Report"> <reportElement positionType="Float" x="0" y="35" width="540" height="75"/> </chart> <categoryDataset> <dataset incrementType="Group" incrementGroup="FirstGroup"/> <categorySeries> <seriesExpression>$P{VALUE_HEADER_P}</seriesExpression> <categoryExpression>$F{FIELD1}</categoryExpression> <valueExpression>new Double($F{VALUE}.doubleValue() / 2d)</valueExpression> </categorySeries> </categoryDataset> <barPlot isShowTickMarks="true" isShowTickLabels="true"> <plot/> </barPlot> </barChart> </band> </detail> </jasperReport> And finally the data source file. public class DataSource extends AbstractTableModel { private String[] columnNames = null;; private String[] columnDisplayNames = null; /** * ArrayList of ArrayLists */ private ArrayList<ArrayList> data = null; public DataSource(String[] columns, ArrayList records) { columnNames = columns; data = records; } public void setColumnDisplayNames(String[] displayNames) { columnDisplayNames = displayNames; } public String[] getColumnDisplayNames() { return columnDisplayNames; } public int getColumnCount() { return this.columnNames.length; } public String getColumnName(int columnIndex) { return this.columnNames[columnIndex]; } public int getRowCount() { return this.data.size(); } public Object getValueAt(int rowIndex, int columnIndex) { ArrayList record = (ArrayList) data.get(rowIndex); return record.get(columnIndex); } public ArrayList getData() { return data; } }