Can anybody help me pls?

Question

im having a problem with my jsp and its giving me a null pointer exception
<%
                         if(request.getParameter("username")!=null){
                              String username=request.getParameter("username");
                              String password=request.getParameter("password");     
                                   try{
                                        statement = connection.createStatement();
                                        String query ="select password,username,usergroup_name from user where username='" username.trim()"'";
                                        rs = statement.executeQuery(query);
                                             if(rs.next()){
                                                       if(password.trim().equals(rs.getString("password"))){
                                                            if(rs.getString("usergroup_name").equals("administrator")){
                                                                 session.setAttribute("the_user",rs.getString("username"));
                                                                 session.setAttribute("the_role",rs.getString("usergroup_name"));
                                                                 response.sendRedirect("adminhome.jsp");
                                                            if(rs.getString("usergroup_name").equals("user")){
                                                                 session.setAttribute("the_user",rs.getString("username"));
                                                                 session.setAttribute("the_role",rs.getString("usergroup_name"));
                                                                 response.sendRedirect("userhome.jsp");
                                                       else{ out.println("<li>Incorrect Password!</li>"); }
                                             else{ out.println("<li>Username doesn't Exist</li>");     }
                                   }catch(Exception e){ }                    
               %>
java.lang.NullPointerException
     org.apache.jsp.adminlogin_jsp._jspService(adminlogin_jsp.java:93)
     org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

Answer 1

Firstly, neat and orderly code is goddly when you are expecting help from others!!!
<%
  String username = request.getParameter("username");
  String password = request.getParameter("password");
  if ( username !=null && password != null )
    try
      // This assumes that a connection variable exists and is not null
      statement = connection.createStatement();
      String query ="select password,username,usergroup_name from user where username='" +username.trim()+"'";
      rs = statement.executeQuery(query);
      if ( rs.next() )
        if ( password.trim().equals(rs.getString("password")) )
          String ug = rs.getString("usergroup_name");
          // This assumes that a session variable exists and is not null
          session.setAttribute("the_user", rs.getString("username"));
          session.setAttribute("the_role", rs.getString("usergroup_name"));
          if ( ug.equals("administrator") ) response.sendRedirect("adminhome.jsp");
          if ( ug.equals("user") ) response.sendRedirect("userhome.jsp");
        else out.println("<li>Incorrect Password!</li>");
      else out.println("<li>Username doesn't Exist</li>");
    catch ( Exception e )
      // The exception stack trace will appear in the stdout.log file
      // $tomcat_home/logs
      e.printStackTrace();
%>HTH