我试图在用户单击更新按钮时在文本文件中写入和替换特定行，但事实证明，它会将更改/更新的行写入换行符。我对此有JTable。谢谢您的帮助！对不起，如果我的代码有点混乱。

    int updatedfoodcode = Integer.parseInt(fieldFoodCode.getText());
    String updatedfoodname = fieldFoodName.getText();
    int updatedfoodprice = Integer.parseInt(fieldFoodPrice.getText());
    int updatedfoodquantity = Integer.parseInt(fieldFoodQuantity.getText());
    int row = jTable1.getSelectedRow();
    foodlist.get(row).foodCode = updatedfoodcode;
    foodlist.get(row).foodName = updatedfoodname;
    foodlist.get(row).foodPrice = updatedfoodprice;
    foodlist.get(row).foodQuantity = updatedfoodquantity;
    dtm.setRowCount(0);

    for(int i = 0; i < foodlist.size(); i++){
        Object[] obj = {foodlist.get(i).foodCode,foodlist.get(i).foodName,foodlist.get(i).foodPrice,foodlist.get(i).foodQuantity};
        dtm.addRow(obj);
   }

    Food reload = new Food(
        Integer.parseInt(fieldFoodCode.getText()),fieldFoodName.getText(),Integer.parseInt(fieldFoodPrice.getText()),Integer.parseInt(fieldFoodQuantity.getText())
    );
    foodlist.set(row,reload);
            try {
                fileWriter =  new FileWriter("C:\\Users\\TEMP\\Documents\\Music\\Music\\Documents\\NetBeansProjects\\inventorytry\\src\\inventorytry\\inventory.txt",true);
                String write = "";
                for(int i = 0; i < foodlist.size(); i++)
                    if(i == row)
                    {
                        write += foodlist.get(i).foodCode + " " +  foodlist.get(i).foodName + " " + foodlist.get(i).foodPrice + " " + foodlist.get(i).foodQuantity + "\n";
                    }                
           fileWriter.write(write);
           fileWriter.close();
            }
            catch (Exception e){
          System.out.println("" + e);
        }
}