我正在编写一种自动提款机程序，该程序会将数据输出到文件中(是​​的，我知道它不是英语，但这不是重点)，并且遇到了错误。

当我尝试使用PrintWriter它不起作用时，我不知道为什么。

public void writeFooter(List list) throws Exception{

int amountSold = 0;

int amountNotSold = 0;

int moneyRecieved = 0;

openStreams();

printer.println("Проданные товары: ");

for(int i = 0; i <= list.size() - 1;i++){

if(list.get(i).isSold()){

writeToFile(list.get(i), dir);

amountSold++;

moneyRecieved += list.get(i).getPrice();

}

}

printer.println();

printer.println("Не проданные товары: ");

for(int i = 0; i <= list.size() - 1; i ++){

if(!list.get(i).isSold()){

writeToFile(list.get(i), dir);

amountNotSold++;

}

}

printer.println();

printer.println("Всего: "+list.size());

printer.println("Кол-во проданно: "+ amountSold);

printer.println("Кол-во не проданно: "+ amountNotSold);

printer.println("Выручка: "+ moneyRecieved);

printer.flush();

System.out.print(printer.checkError());

closeStreams();

}

private void openStreams() throws IOException{

writer = new FileWriter(file,true);

buffer = new BufferedWriter(writer);

printer = new PrintWriter(buffer);

}

private void closeStreams() throws IOException{

printer.flush();

printer.close();

buffer.close();

writer.close();

}

public void writeToFile(Purchase purchase,String dir) throws Exception{

file = new File(dir);

if(!file.exists()){

file.createNewFile();

}

openStreams();

printer.println(purchase.getName() + " По цене: " + purchase.getPrice() + "руб");

closeStreams();

}

for循环有效，但各行。这真的让我感到困惑！我已经尝试过checkError()并且得到了true，但这仍然无济于事。

有人可以解释我在做什么错吗？