//file: stringa nome file
//car = carattere da sostituire allo spazio

                fileCorr = new File(file);
               String ristemp="";
               char temp;
               int carInt, count=0;
               if (fileCorr.exists())
               {
                    BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream(file)));
                    while ((carInt=in.read())!=-1)
                    {
                        temp = (char) carInt;
                        if( temp == ' ')
                        {
                            ristemp=car+"";
                            count++;
                        }
                        else
                        {
                            ristemp=temp+"";
                        }

                    }
                    in.close();
                     if(count>0)
                    {
                        BufferedWriter dest = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file)));
                        dest.write(ristemp);
                        dest.close();
                    }