public boolean next() throws JRException;

- called on the data source object by the reporting engine when iterating through the data at report-filling time

public Object getFieldValue(JRField jrField) throws JRException;

- provides the value for each report field in the current data source record

JDBC data sources: the JRResultSetDataSource class

- Wraps a java.sql.ResultSet object. Represents the most commonly used data source implementations when report data are extracted from a relational database. If a java.sql.Connection is passed to the engine instead, it executes first the related query and stores the returned java.sql.ResultSet object in a JRResultSetDataSource instance.

JavaBean data sources: JRBeanArrayDataSource and JRBeanCollectionDataSource

- Represent implementations that can wrap collections or arrays of JavaBean objects. Each object inside the array or the collection is considered a record in this type of data source. The mapping between a particular JavaBean property and the corresponding report field is made by naming conventions. The name of the report field must be the same as the name of the JavaBean property as specified by the JavaBean specifications.
- A special field mapping in JavaBean data sources can be obtained using the reserved value (ie. _THIS ) stored in the CURRENT_BEAN_MAPPING constant. If the report field name/description matches this constant value (the letter case is important), then the data source will return the current bean as the field value.

Map-based data sources: JRMapArrayDataSource and JRMapCollectionDataSource

- These implementations are useful if the parent application already stores the reporting data available in-memory as java.util.Map objects. Each Map object in the wrapped array or collection is considered a virtual record in the data source, and the value of each report field is extracted from the map using the report field name as the key

TableModel data sources: the JRTableModelDataSource class

- Wraps a javax.swing.table.TableModel object. Columns in the wrapped TableModel object can be accessed either by their names or by their 0-based indexes.

XML data sources: the JRXmlDataSource class

- A data source implementation based on DOM, which uses XPath expressions to select data from the XML document. Records in the XML data source are represented by node elements selected through the XPath expression. Field values are retrieved from each record using the XPath expression provided by the PROPERTY_FIELD_EXPRESSION custom property defined at field level. The use of the field description (<fieldDescription> element in JRXML) to specify the XPath expression is still supported, but is now discouraged, the above mentioned custom property taking precedence over the field description.

CSV data sources: the JRCsvDataSource class

- Represents an implementation for data sources which retrieve their data from structured text files, usually CSVs. Field values are retrieved using their column index.

XLS/XLSX data sources: the ExcelDataSource class

- Represents an implementation for data sources which retrieve their data from Excel documents (workbooks). Report-field mapping for this data source implementation is also based on the field column index.

Empty data sources: the JREmptyDataSource class

- Simulates a data source with a given number of virtual empty records inside. It is is used by the UI tools to offer basic report preview functionality, or in special report templates, or for testing and debugging purposes.

• public boolean supportsGetFieldsOperation();
• public JRField[] getFields(JasperReport report) throws JRException, UnsupportedOperationException;
• public JRDataSource create(JasperReport report) throws JRException;
• public void dispose(JRDataSource dataSource) throws JRException;

• if the argument is fill1 then data will be extracted from the CustomDataSource object.
• if the argument is fill2 then data will be extracted from the CustomTableModel object.
• if the argument is fill3 then data will be extracted from the CustomBeanFactory object as JavaBean array.
• if the argument is fill4 then data will be extracted from the CustomBeanFactory object as JavaBean Collection.

 private Object[][] data =
  {
   {"Berne", 22, "Bill Ott", "250 - 20th Ave."},
   {"Berne", 9, "James Schneider", "277 Seventh Av."},
   {"Boston", 32, "Michael Ott", "339 College Av."},
   {"Boston", 23, "Julia Heiniger", "358 College Av."},
   {"Chicago", 39, "Mary Karsen", "202 College Av."},
   {"Chicago", 35, "George Karsen", "412 College Av."},
   {"Chicago", 11, "Julia White", "412 Upland Pl."},
   {"Dallas", 47, "Janet Fuller", "445 Upland Pl."},
   {"Dallas", 43, "Susanne Smith", "2 Upland Pl."},
   {"Dallas", 40, "Susanne Miller", "440 - 20th Ave."},
   {"Dallas", 36, "John Steel", "276 Upland Pl."},
   {"Dallas", 37, "Michael Clancy", "19 Seventh Av."},
   {"Dallas", 19, "Susanne Heiniger", "86 - 20th Ave."},
   {"Dallas", 10, "Anne Fuller", "135 Upland Pl."},
   {"Dallas", 4, "Sylvia Ringer", "365 College Av."},
   {"Dallas", 0, "Laura Steel", "429 Seventh Av."},
   {"Lyon", 38, "Andrew Heiniger", "347 College Av."},
   {"Lyon", 28, "Susanne White", "74 - 20th Ave."},
   {"Lyon", 17, "Laura Ott", "443 Seventh Av."},
   {"Lyon", 2, "Anne Miller", "20 Upland Pl."},
   {"New York", 46, "Andrew May", "172 Seventh Av."},
   {"New York", 44, "Sylvia Ott", "361 College Av."},
   {"New York", 41, "Bill King", "546 College Av."},
   {"Oslo", 45, "Janet May", "396 Seventh Av."},
   {"Oslo", 42, "Robert Ott", "503 Seventh Av."},
   {"Paris", 25, "Sylvia Steel", "269 College Av."},
   {"Paris", 18, "Sylvia Fuller", "158 - 20th Ave."},
   {"Paris", 5, "Laura Miller", "294 Seventh Av."},
   {"San Francisco", 48, "Robert White", "549 Seventh Av."},
   {"San Francisco", 7, "James Peterson", "231 Upland Pl."}
  };
  
  private int index = -1;

 public boolean next() throws JRException
 {
  index++;
  return (index < data.length);
 }

 public Object getFieldValue(JRField field) throws JRException
 {
  Object value = null;
  String fieldName = field.getName();

  if ("the_city".equals(fieldName))
  {
   value = data[index][0];
  }
  else if ("id".equals(fieldName))
  {
   value = data[index][1];
  }
  else if ("name".equals(fieldName))
  {
   value = data[index][2];
  }
  else if ("street".equals(fieldName))
  {
   value = data[index][3];
  }

  return value;
 }

 public void fill1() throws JRException
 {
  long start = System.currentTimeMillis();
  //Preparing parameters
  Map parameters = new HashMap();
  parameters.put("ReportTitle", "Address Report");
  parameters.put("DataFile", "CustomDataSource.java");

  JasperFillManager.fillReportToFile("build/reports/DataSourceReport.jasper", 
    parameters, new CustomDataSource());
  System.err.println("Filling time : " + (System.currentTimeMillis() - start));
 }

public class CustomBean
{
 private String city;
 private Integer id;
 private String name;
 private String street;

 public CustomBean(
  String pcity,
  Integer pid,
  String pname,
  String pstreet
  )
 {
  city = pcity;
  id = pid;
  name = pname;
  street = pstreet;
 }

 public CustomBean getMe()
 {
  return this;
 }

 public String getCity()
 {
  return city;
 }

 public Integer getId()
 {
  return id;
 }

 public String getName()
 {
  return name;
 }

 public String getStreet()
 {
  return street;
 }
}

public class CustomBeanFactory
{
 private static CustomBean[] data =
  {
   new CustomBean("Berne", 9, "James Schneider", "277 Seventh Av."),
   new CustomBean("Berne", 22, "Bill Ott", "250 - 20th Ave."),
   new CustomBean("Boston", 23, "Julia Heiniger", "358 College Av."),
   new CustomBean("Boston", 32, "Michael Ott", "339 College Av."),
   new CustomBean("Chicago", 39, "Mary Karsen", "202 College Av."),
   new CustomBean("Chicago", 35, "George Karsen", "412 College Av."),
   new CustomBean("Chicago", 11, "Julia White", "412 Upland Pl."),
   new CustomBean("Dallas", 47, "Janet Fuller", "445 Upland Pl."),
   new CustomBean("Dallas", 43, "Susanne Smith", "2 Upland Pl."),
   new CustomBean("Dallas", 40, "Susanne Miller", "440 - 20th Ave."),
   new CustomBean("Dallas", 36, "John Steel", "276 Upland Pl."),
   new CustomBean("Dallas", 37, "Michael Clancy", "19 Seventh Av."),
   new CustomBean("Dallas", 19, "Susanne Heiniger", "86 - 20th Ave."),
   new CustomBean("Dallas", 10, "Anne Fuller", "135 Upland Pl."),
   new CustomBean("Dallas", 4, "Sylvia Ringer", "365 College Av."),
   new CustomBean("Dallas", 0, "Laura Steel", "429 Seventh Av."),
   new CustomBean("Lyon", 38, "Andrew Heiniger", "347 College Av."),
   new CustomBean("Lyon", 28, "Susanne White", "74 - 20th Ave."),
   new CustomBean("Lyon", 17, "Laura Ott", "443 Seventh Av."),
   new CustomBean("Lyon", 2, "Anne Miller", "20 Upland Pl."),
   new CustomBean("New York", 46, "Andrew May", "172 Seventh Av."),
   new CustomBean("New York", 44, "Sylvia Ott", "361 College Av."),
   new CustomBean("New York", 41, "Bill King", "546 College Av."),
   new CustomBean("Oslo", 45, "Janet May", "396 Seventh Av."),
   new CustomBean("Oslo", 42, "Robert Ott", "503 Seventh Av."),
   new CustomBean("Paris", 25, "Sylvia Steel", "269 College Av."),
   new CustomBean("Paris", 18, "Sylvia Fuller", "158 - 20th Ave."),
   new CustomBean("Paris", 5, "Laura Miller", "294 Seventh Av."),
   new CustomBean("San Francisco", 48, "Robert White", "549 Seventh Av."),
   new CustomBean("San Francisco", 7, "James Peterson", "231 Upland Pl.")
  };  
		
 public static Object[] getBeanArray()
 {
  return data;
 }

 public static Collection getBeanCollection()
 {
  return Arrays.asList(data);
 }
}

• if the argument is fill3 then data will be extracted as JavaBean array, using the getBeanArray() method. At fill time, a JRBeanArrayDataSource object is passed as argument to the fillReportToFile() method in the JasperFillManager class.
• if the argument is fill4 then data will be extracted as JavaBean Collection (java.util.List), using the getBeanCollection() method. At fill time, a JRBeanCollectionDataSource object is passed as argument to the fillReportToFile() method in the JasperFillManager class.

 public void fill3() throws JRException
 {
  long start = System.currentTimeMillis();
  //Preparing parameters
  Map parameters = new HashMap();
  parameters.put("ReportTitle", "Address Report");
  parameters.put("DataFile", "CustomBeanFactory.java - Bean Array");

  JasperFillManager.fillReportToFile("build/reports/DataSourceReport.jasper", 
    parameters, new JRBeanArrayDataSource(CustomBeanFactory.getBeanArray()));
  System.err.println("Filling time : " + (System.currentTimeMillis() - start));
 }

 public void fill4() throws JRException
 {
  long start = System.currentTimeMillis();
  //Preparing parameters
  Map parameters = new HashMap();
  parameters.put("ReportTitle", "Address Report");
  parameters.put("DataFile", "CustomBeanFactory.java - Bean Collection");

  JasperFillManager.fillReportToFile("build/reports/DataSourceReport.jasper", 
    parameters, new JRBeanCollectionDataSource(CustomBeanFactory.getBeanCollection()));
  System.err.println("Filling time : " + (System.currentTimeMillis() - start));
 }

 public class CustomTableModel extends AbstractTableModel
 {
  private String[] columnNames = {"the_city", "id", "name", "street"};

  private Object[][] data =
  {
   {"Berne", 22, "Bill Ott", "250 - 20th Ave."},
   {"Berne", 9, "James Schneider", "277 Seventh Av."},
   {"Boston", 32, "Michael Ott", "339 College Av."},
   {"Boston", 23, "Julia Heiniger", "358 College Av."},
   {"Chicago", 39, "Mary Karsen", "202 College Av."},
   {"Chicago", 35, "George Karsen", "412 College Av."},
   {"Chicago", 11, "Julia White", "412 Upland Pl."},
   {"Dallas", 47, "Janet Fuller", "445 Upland Pl."},
   {"Dallas", 43, "Susanne Smith", "2 Upland Pl."},
   {"Dallas", 40, "Susanne Miller", "440 - 20th Ave."},
   {"Dallas", 36, "John Steel", "276 Upland Pl."},
   {"Dallas", 37, "Michael Clancy", "19 Seventh Av."},
   {"Dallas", 19, "Susanne Heiniger", "86 - 20th Ave."},
   {"Dallas", 10, "Anne Fuller", "135 Upland Pl."},
   {"Dallas", 4, "Sylvia Ringer", "365 College Av."},
   {"Dallas", 0, "Laura Steel", "429 Seventh Av."},
   {"Lyon", 38, "Andrew Heiniger", "347 College Av."},
   {"Lyon", 28, "Susanne White", "74 - 20th Ave."},
   {"Lyon", 17, "Laura Ott", "443 Seventh Av."},
   {"Lyon", 2, "Anne Miller", "20 Upland Pl."},
   {"New York", 46, "Andrew May", "172 Seventh Av."},
   {"New York", 44, "Sylvia Ott", "361 College Av."},
   {"New York", 41, "Bill King", "546 College Av."},
   {"Oslo", 45, "Janet May", "396 Seventh Av."},
   {"Oslo", 42, "Robert Ott", "503 Seventh Av."},
   {"Paris", 25, "Sylvia Steel", "269 College Av."},
   {"Paris", 18, "Sylvia Fuller", "158 - 20th Ave."},
   {"Paris", 5, "Laura Miller", "294 Seventh Av."},
   {"San Francisco", 48, "Robert White", "549 Seventh Av."},
   {"San Francisco", 7, "James Peterson", "231 Upland Pl."}
  };

  public CustomTableModel()
  {
  }

  public int getColumnCount()
  {
   return this.columnNames.length;
  }

  public String getColumnName(int columnIndex)
  {
   return this.columnNames[columnIndex];
  }

  public int getRowCount()
  {
   return this.data.length;
  }

  public Object getValueAt(int rowIndex, int columnIndex)
  {
   return this.data[rowIndex][columnIndex];
  }
 }

 public void fill2() throws JRException
 {
  long start = System.currentTimeMillis();
  //Preparing parameters
  Map parameters = new HashMap();
  parameters.put("ReportTitle", "Address Report");
  parameters.put("DataFile", "CustomTableModel.java");

  JasperFillManager.fillReportToFile("build/reports/DataSourceReport.jasper", 
    parameters, new JRTableModelDataSource(new CustomTableModel()));
  System.err.println("Filling time : " + (System.currentTimeMillis() - start));
 }