hashmap - Is it possible to create copy of Map Iterators in Java? -

public boolean placelizardsbydfs(int noofqueens){         if(noofqueens == 0) {             return true;         }         else {             iterator itforrow  = allowedrows.entryset().iterator();             while (itforrow.hasnext()) {                 double temprow = (double) ((map.entry) itforrow.next()).getkey();                 iterator itforcolumn = allowedcolumns.entryset().iterator();                 while(itforcolumn.hasnext()) {                     double tempcolumn = (double) ((map.entry) itforcolumn.next()).getkey();                     placequeen(temprow, tempcolumn);                     if (placelizardsbydfs(noofqueens - 1))                         return true;                     else                         removequeen(temprow, tempcolumn, temprangeforrow, temprangeforcolumn);                 }             }             return false;         }     } 

i'm trying solve n queens problem. seems bigger inputs, code inefficient. i'm trying optimize reducing no. of rows , columns search deeper levels of recursion. possible pass copy of iterator map? problem i'm facing here whether can pass new iterator next level of recursion without iterator @ higher level getting affected since java call reference?