memory - Facing Problems while displaying entire hashmap - java out of heap space -

public static void main(string args[]) throws filenotfoundexception, ioexception {       filereader in = new filereader("/home/aoblah/downloads/file1.txt");     bufferedreader br = new bufferedreader(in);       // scanner in = null;     string answer = null;     string verb = null;     string line = null;     string [] split_npn = null;     string [] split_pn = null;     string [] split_dp2 = null;     string [] split_dp3 = null;      hashmap<string, hashmap<string, arraylist<string>>> hmap = new hashmap<string, hashmap<string, arraylist<string>>>();      try {           while ((line = br.readline()) != null)         {             if(line.contains("verb"))             {                   verb = line.substring(0, line.indexof("("));                  if(line.contains("npn")){                     string test = line.substring(line.indexof("npn"));                     answer = test.substring(test.indexof("npn"),test.indexof(']'));                       answer = answer.replace(",", " " );                                             split_npn = answer.split(" ");                 }                     if(line.contains("pn")){                     string test = line.substring(line.indexof("pn"));                     answer = test.substring(test.indexof("pn"), test.indexof(']'));                     answer = answer.replace(",", " " );                                             split_pn = answer.split(" ");                 }                  if(line.contains("dp2")){                     string test = line.substring(line.indexof("dp2"));                     answer = test.substring(test.indexof("dp2"), test.indexof(']'));                     answer = answer.replace(",", " " );                                             split_dp2 = answer.split(" ");                 }                 if(line.contains("dp3")){                     string test = line.substring(line.indexof("dp3"));                     answer = test.substring(test.indexof("dp3"), test.indexof(']'));                     answer = answer.replace(",", " " );                      split_dp3 = answer.split(" ");                 }                                   }              if(split_npn != null){                 arraylist<string> npn = new arraylist<string>();                 hmap.put(verb, new hashmap<string, arraylist<string>>());                 for(int = 1; i< split_npn.length; i++){                     npn.add(split_npn[i]);                 }                 npn.trimtosize();                 hmap.get(verb).put("npn", npn);             }              if(split_pn != null){                 arraylist<string> pn = new arraylist<string>();                 hmap.put(verb, new hashmap<string, arraylist<string>>());                 for(int = 1; i< split_pn.length; i++){                     pn.add(split_pn[i]);                 }                 pn.trimtosize();                 hmap.get(verb).put("pn", pn);             }                              if(split_dp2 != null){                 arraylist<string> dp2 = new arraylist<string>();                 hmap.put(verb, new hashmap<string, arraylist<string>>());                 for(int = 1; i< split_dp2.length; i++){                     dp2.add(split_dp2[i]);                 }                 dp2.trimtosize();                 hmap.get(verb).put("dp2", dp2);             }                                              if(split_dp3 != null){                 arraylist<string> dp3 = new arraylist<string>();                 hmap.put(verb, new hashmap<string, arraylist<string>>());                 for(int = 1; i< split_dp3.length; i++){                     dp3.add(split_dp3[i]);                 }                 dp3.trimtosize();                 hmap.get(verb).put("dp3", dp3);             }               system.out.println(hmap);          }      }       catch (filenotfoundexception e) {         // todo auto-generated catch block         e.printstacktrace();     } } 

the file contains entries such

calm(verb,naux,[nullobj,[dp2,down],[dp3,down]],calm).
calms(verb,[sg],calm).
calmed(verb,[sg,pl,en],calm).
calm(verb,[pl,inf],calm).
calming(verb,[ing],calm).
calmly(adv,mv,calmly).
calmness(noun,[sg],calmness).

i storing verbs, categories of prepositions associated , prepositions in nested hash map. have no trouble when printing particular category of prepositions associated verb, when display whole hashmap programs runs , never stops...ending in java out of space heap error. how can fix memory problem?

one suggestion instead of doing system.out.println(hmap);

try print out sequentually:

for(string outerkey: hmap.keyset()) {    system.out.println(outerkey + ": ");    map inner = hmap.get(outerkey);    for(string innerkey : innermap)    {     system.out.print(innerkey + ": ");     system.out.println(inntermap.get(innerkey).tostring());    }  }