NULLPointerException

مرحبا

انا عندي مشكلة في تشغيل هذا الjava Code ولا اعرف السبب لماذا تظهر لي هذه الMessege

Exception in thread "main.java.lang.NullPinterException

at Send.main.java:152

رجاءا حاولو مساعدتي

مع جزيل الشكر

import java.sql.*;
import java.util.*;
import java.util.Date;

import javax.mail.*;
import javax.mail.internet.*;

class Project{

	String email;
	String name;
	long projectID;
	ArrayList mitarbeiter;

	public Project(String n, String em){
  name=n;
  email=em;
	}	
}

class Mitarbeiter{

	String vorname;
	String nachname;
	long userID;
	boolean has;

	public Mitarbeiter(String v, String n, long ID, boolean h){
  vorname = v;
  nachname = n;
  userID = ID;
  has = h;
	}	
}

public class SendMail {

	public Project [] projects = {new Project("LC", "email"), new Project("Professional Services", "email"),
 	 new Project("ASP&Support", "email"),new Project("Research&Development", "email")}; //Projekte

	public SendMail() {
  
  Statement stmt;
  Connection myConn;
  
  try {
 	 Class.forName("com.mysql.jdbc.Driver");
 	 myConn = DriverManager.getConnection(
   	 "jdbc:mysql://127.0.0.1/pr", "root", "h");
 	 stmt = myConn.createStatement();
  } catch (ClassNotFoundException e1) { 	 
 	 e1.printStackTrace();
 	 return;
  } catch (SQLException e1) {
 	 e1.printStackTrace();
 	 return;
  }

  Calendar cal = new GregorianCalendar();
  cal.setTime(new Date());
  
  //aktuelle Zeit in Millisekunden
  long zeit2 = cal.getTimeInMillis();
  
  //aktuele Zeit minus 24 Stunden in Millisekunden
  long zeit = zeit2 - (24 * 60 * 60 * 1000);
        
  for (int i=0;i<projects.length;i++){ 	 
 	 try {
    ResultSet rs; 
    rs = stmt
    .executeQuery("Select m.UserID,p.ProjectID, u.FirstName, u.LastName from Project"+
      " as p ,MemberOfProject as m, User as u where p.Name='"+projects.name+
      "and m.ProjectID = p.ProjectID and m.UserID = u.UserID");
    
    if (rs != null) {
   	 while (rs.next()) {
      ResultSet myResultSet2 = stmt
      .executeQuery("Select StartedAT,FinishedAt from Activity "
        + ""
        + "where UserID='"
        + rs.getLong("UserID")
        + "' and ProjectID='"
        + rs.getLong("ProjectID")
        + "'and FinishedAt between '"
        + zeit2
        + "' and '" + zeit + "'");
      
      boolean hat = false;
      if (myResultSet2 != null){
     	 hat = true;	
      }
      projects.mitarbeiter.add(new Mitarbeiter(rs.getString("LastName"),
        rs.getString("FirstName"), rs.getLong("ProjectID"), hat));
   	 }
    }
      
 	 } catch (SQLException e) {
    e.printStackTrace();
 	 }   	 
  }
	}

	public static void postMail(String recipient, String subject,
 	 String message, String from) throws MessagingException {
  Properties props = new Properties();
  props.put("mail.smtp.host", "mail.web.de");
  Session session = Session.getDefaultInstance(props);

  Message msg = new MimeMessage(session);

  InternetAddress addressFrom = new InternetAddress(from);
  msg.setFrom(addressFrom);

  InternetAddress addressTo = new InternetAddress(recipient);
  msg.setRecipient(Message.RecipientType.TO, addressTo);

  msg.setSubject(subject);
  msg.setContent(message, "text/plain");
  Transport.send(msg);
	}

	public static void main(String args[]) throws Exception {
  SendMail mail = new SendMail();
  String text  = "";
  String email = "";
  
  for (int i=0; i<mail.projects.length;i++){
 	 email = mail.projects.email;
 	 text = "Hallo";
 	 StringBuffer buffer = new StringBuffer();
 	 
 	 for(int n=0;n<mail.projects.mitarbeiter.size();n++){
    Mitarbeiter ma = (Mitarbeiter)mail.projects.mitarbeiter.get(n);
    text +=("Name: " + ma.vorname + " " + ma.nachname + "\n");
    if (ma.has){
   	 text +=("Hat Eintragungen in Zeiterfassung getätigt\n\n");	
    }else {
   	 text +=("Hat keine Eintragungen in Zeiterfassung getätigt\n\n");
    }    
 	 }
 	 
 	 postMail(email, "Zeiterfassung", text,
 	 "had@web.de");
  }
	}
}