replace duplicate values in hashmap java -

i have hashmap contains student id key , string value.

map<integer, string> data = new hashmap<integer, string>(); 

it contains data

1 2 b 3 4 c 5 b 6 

i want find duplicate values in map , replace them integer values. i.e. want map like

1 1 2 2 3 1 4 3 5 2 6 1 

i.e. map shud pick first value(a), find keys value , replace value of keys 1. pick second value(b) find keys , replace them 2 , on. file reading large cannot replace keys manually specifying each key. so, have tried far is

map<integer,integer> finalmap = new hashmap<integer,integer>(); int a=0;      list mapkey = new arraylist(data.keyset());      list mapval = new arraylist(data.values());      iterator valit = mapval.iterator();      while(valit.hasnext()){          a=a+1;          object valuet = valit.next();           iterator keyit = mapkey.iterator();          while(keyit.hasnext()){              object keyt = keyit.next();               string comp1 = data.get(keyt).tostring();              string comp2 = valuet.tostring();              if(comp1.equals(comp2)){                  finalmap.put((string)keyt,a);              }           }       }   

but not giving me correct output. doesnt start a=1. think first calculates incremented values of a. have text file 1000 records. , output is

1 1000 2 987 3 1000 4 298 5 987 6 1000 

i dont know m wrong. please me regarding this. thank you

first thing need understand, there no such thing "first" value in hashmap. if want ordered base on key, should use treemap instead.

if ordering not concern you, , need same integer replace same value, there lots of way do. 1 way (code not accurate, should demonstrate idea):

// setup map of oldvalue newvalue hashmap<string, integer> valuemap = ...; int = 0; (string oldvalue : data.values()) {     if ( ! valuemap.contains(oldvalue )) {         valuemap.put(oldvalue, ++i);     } }  // replace in data (map.entry<integer, string> dataentry : data.entryset()) {     finalmap.put(dataentry.getkey(), valuemap.get(dataentry.getvalue()); }