public static void writeFile(List<Product> products,String fileName, int mode) throws IOException { boolean modeEnd=false;int size=0; if(mode==1){modeEnd=true;size=products.size()-1;} String stringProduct=""; FileOutputStream fileWriter = new FileOutputStream(fileName,modeEnd); //System.out.println(size); for (int i=size;i<products.size();i++){ stringProduct=products.get(i).id+products.get(i).productName+products.get(i).price+products.get(i).quntity; fileWriter.write(stringProduct.getBytes(StandardCharsets.ISO_8859_1)); fileWriter.write(10); } fileWriter.close();