grails - Why values of list is changing while sending to a service -

i new grails , developing web application.

i have list of long values getting ids of domain class objects.

initially list [1,2,3]. need use list of values in service class saving associations.

but same list getting in service class [49,50,51]

why difference of 48 occurred? , how can list same sent.

controller class:

def createquestion(createquestioncommand createquestioncmd) {    if( createquestioncmd.haserrors() ) {      render(view:"create_question", model:[createquestioncmd:createquestioncmd , tags:tag.list()])    } else {      question question = new question()      question.title=createquestioncmd.title      question.description=createquestioncmd.description      list tags= createquestioncmd.tags      question = questionservice.create(question,tags)      render(view: "question_submitted")    }  } 

service class:

def create(question question, list<long> tagid) {    list<tag> taglist=gettagsbyid(tagid)    question.save( failonerror:true )    iterator itr=taglist.iterator();    while(itr.hasnext()) {       tag tag=itr.next()       question.addtotags(tag).save()    } }  def gettagsbyid(list tagid){    iterator itr=tagid.iterator();    list<tag> tags    while(itr.hasnext()) {      long id=itr.next()      println "value of id : "      println id      println id.getclass().getname()      tag tag=tag.findbyid(id)      tags.add(tag)    }    return tags  } 

createquestioncmd.tags list<string> , trying place list<long>