Java: LinkedHashMaps overlaps over themselves -

i want create copy of linked hash map , want remove values (from list) instead of first entry. here got:

linkedhashmap<string, list<value>> facetsincategoriescopy = new linkedhashmap<>(facetsincategories);  if (!facets.equals("something")) {     (list<value> value : facetsincategoriescopy.values()) {         if (value.size() > 1) {             int nbrofelements = value.size();             (int = nbrofelements-1; > 0; i--) {                 value.remove(i);             }         }     } } 

after operation turns out facetsincategories modified too. why? , how solve issue? appreciated.

i don't have 50 reputation add comment. see answer assigning hashmap hashmap

essentially, copy constructor used make new map has references mutable objects i.e. facetsincategories , update when update facetsincategoriescopy map.

the solution instead deep copy instead. have added test code below, used string instead of value

  //test https://stackoverflow.com/questions/27324315/   public static void teststacko_q_27324315() {      map<string, list<string>> facetsincategories = new linkedhashmap<string, list<string>>();     string[] values = new string[]{"test1", "test2", "test3"};     list<string> valueslist = new arraylist<string>(arrays.aslist(values));     facetsincategories.put("test", valueslist);      map temp = collections.unmodifiablemap(facetsincategories);     linkedhashmap<string, list<string>> facetsincategoriescopy = (linkedhashmap<string, list<string>>)deepcopy(temp);      string facets = "test_me";      if (!facets.equals("something")) {         (list<string> value : facetsincategoriescopy.values()) {             if (value.size() > 1) {                 int nbrofelements = value.size();                 (int = nbrofelements-1; > 0; i--) {                     value.remove(i);                 }             }         }     }      system.out.println(facetsincategories);     system.out.println(facetsincategoriescopy); }  public static <k1, k2, v> map<k1, list<v>> deepcopy(       map<k1, list<v>> original){        map<k1, list<v>> copy = new linkedhashmap<k1, list<v>>();       for(map.entry<k1, list<v>> entry : original.entryset()){           copy.put(entry.getkey(), new arraylist<v>(entry.getvalue()));       }       return copy;   }