java - Issue with updating multiple values with the same key using HashMap -

i'm having issue 1 key/value pair getting updated properly, other values same key not getting updated. i'm using hashmap consists of list of strings (item nbr) key , values stored list of strings (po nbr), 1 many in regard. below code have implementing hashmap stuck. appreciated.

public void process(list<pobean> exceldata,list<string> errors) throws customexception  {            map<string,arraylist<string>> ponbritemnbrmap = new hashmap<string, arraylist<string>>();     arraylist<string> ponbrlist = new arraylist<string>();      int recordcount = exceldata.size();      for(pobean bean : exceldata)     {                                                if(rowvalidator.validate(bean, errors))         {             if (!newerrorinrow(errors))              {                 ponbrlist.add(bean.getpoid());                 ponbritemnbrmap.put(bean.getitemnbr(),bean.getpoid());             }                    }     }      list<dutyfees> dutyfeestempdao = myservice.getassocidbypoanditemnbr(new arraylist<string>(ponbritemnbrmap.keyset()),new arraylist<string>(ponbritemnbrmap.values()));                 for(dutyfees duty : dutyfeestempdao)     {            double dutyfees = new double(0);         if(ponbritemnbrmap.containskey(duty.getitemnbr()) && ponbritemnbrmap.containsvalue(duty.getpoid()))          {                            for(pobean dutybean : exceldata)             {                 if(duty.getpoid().equals(dutybean.getpoid()) && duty.getitemnbr().equals(dutybean.getitemnbr()))                 {                     dutyfees = new double(dutybean.getdutyfees());                     break;                 }             }             boolean result = myservice.updatedutyfeesbyassocid(duty.getassocid(), dutyfees);                     }                                    }        } 

you want 1 many code has 1 one

hashmap<string,string> ponbritemnbrmap = new hashmap<string,string>(); 

one string key 1 string value

the part in italics in contrast part in bold question.

i'm using hashmap consists of list of strings (item nbr) key , values stored list of strings (po nbr), so 1 many in regard.

italics means many many. bold means 1 many.

anyhow, let me give both implementation play with.

public class test {   public static void main(string[] args) {      system.out.println("= 1 many =");     map<string, list<string>> stringlistmap = new hashmap<>();     string key = "list of 4 strings";     list<string> valueslist = arrays.aslist("one","two","three","four");     stringlistmap.put(key,valueslist);     stringlistmap.foreach((strings, strings2) -> system.out.println(strings.tostring() + strings2.tostring()));      system.out.println("= many many =");     map<list<string>, list<string>> listlistmap = new hashmap<>();     list<string> keys = arrays.aslist("1","2","3","4");     list<string> values = arrays.aslist("one","two","three","four");     listlistmap.put(keys,values);     listlistmap.foreach((strings, strings2) -> system.out.println(strings.tostring() + strings2.tostring()));     } } 

---

edit response comment. not sure mean in comment, see couple of problems. first when putting in map putting seems item number , po id, both seem of type single strings , not arraylist. not sure how able compile that. unless getpoid getpoids , returns list. talking line

ponbritemnbrmap.put(bean.getitemnbr(),bean.getpoid()); 

now regarding

new arraylist<string>(ponbritemnbrmap.values()) 

you can not initialize array list that.

i don't know signature of getassocidbypoanditemnbr function can't suggest answer. however, if want send map values send directly why put in constructor argument new arraylist<>()?