再次发帖，急求高手解决ireport报表问题！！
如下是我的代码，运行到jasperPrint =JasperFillManager.fillReport(jasperReport,reportParams,jrds);时，出现如下错误Exception in thread "main" java.lang.NullPointerException
  at net.sf.jasperreports.engine.fill.JRFiller.fillReport(JRFiller.java:89)
  at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:601)
  at page.myreport2.reportName(myreport2.java:67)
  at page.myreport2.main(myreport2.java:84)
Java Result: 1
到底是怎么回事啊，急死了！！！


package page;
import java.io.File;
import java.sql.*;
import java.util.HashMap;
import java.util.Map;
import net.sf.jasperreports.engine.JRDataSource;
import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JRField;
import net.sf.jasperreports.engine.JasperFillManager;
import net.sf.jasperreports.engine.JRResultSetDataSource;
import net.sf.jasperreports.engine.JasperCompileManager;
import net.sf.jasperreports.engine.JasperExportManager;

import net.sf.jasperreports.engine.JasperPrint;
import net.sf.jasperreports.engine.JasperReport;
import net.sf.jasperreports.engine.design.JasperDesign;

import net.sf.jasperreports.engine.util.JRLoader;
import net.sf.jasperreports.engine.xml.JRXmlLoader;
import net.sf.jasperreports.view.JasperViewer;
public class myreport2
{
 public void reportName() throws JRException
 {
  JRResultSetDataSource jrds = null;
  JasperPrint jasperPrint = null;
  Map reportParams = new HashMap();
  ResultSet rs = null;
  Connection con = null;
 java.sql.Statement stmt = null;
  String sql = "select * from danci";
  try
  {
  //动态获取
  JasperDesign jasperDesign =new JasperDesign();
  JasperReport jasperReport=(JasperReport)JRLoader.loadObject("report4.jasper");
  //jasperDesign=JRXmlLoader.load("report4");
   
 // JasperReport jasperReport =JasperCompileManager.compileReport(jasperDesign);
  //建立连接
 

  con = DriverManager.getConnection("jdbc:sqlserver://localhost\\MSSQLSERVER:1433;databaseName=book","yuanxiaofei","123");
  stmt = con.createStatement();
  rs = stmt.executeQuery(sql);
  rs.next();
  jrds = new JRResultSetDataSource(rs);
  
  reportParams.put("parameter1", "missile");
  if(jasperReport==null)
  System.out.println("123");
  if(jrds==null)
  System.out.println("111");
  if(reportParams==null)
  System.out.println("123");
 jasperPrint =JasperFillManager.fillReport(jasperReport,reportParams,jrds);//运行到这出问题了！！！

  //调出JasperViewer进行打印预览
  JasperViewer.viewReport(jasperPrint);
  rs.close();
  stmt.close();
  con.close();
  }
 catch(SQLException ex)
  {
  ex.printStackTrace();
  }

 }


public static void main(String args[]) throws JRException, dori.jasper.engine.JRException{
new myreport2().reportName();

}
}


------解决方案--------------------
空指针 有可能你的数据源的信息和对应的模板上的参数不一致 有缺失