无法打印到文本文件

Question

Input file ViewOrder.dat contains

inv1102;p1600;brush;2;26.0;Partially Full

This is the java Code

public void viewBackOrder() {

    File fileViewOrder = new File("ViewOrder.dat");
    File fileViewBackOrder = new File("ViewBackOrder.dat");
    Scanner input = new Scanner(System.in);

    String orderNo, itemNo, itemName, itemQty, itemPrice, status;

    try {

        BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(fileViewOrder)));
        BufferedWriter bw = new BufferedWriter(new FileWriter(fileViewBackOrder));
        String line = null;

        while ((line = br.readLine()) != null) {

            String tokens[] = line.split(";");

            orderNo = tokens[0];
            itemNo = tokens[1];
            itemName = tokens[2];
            itemQty = tokens[3];
            itemPrice = tokens[4];
            status = tokens[5];

            System.out.println("Order No: [" + orderNo + "]" + " Item No: [" + itemNo + "]" + " Back Order No: [" + itemQty + "]\n");

        }

        System.out.print("Print Back Order List to file: ");
        String choice = input.next();
        if (choice.equalsIgnoreCase("y")) {

            while ((line = br.readLine()) != null) {

                String tokens[] = line.split(";");

                orderNo = tokens[0];
                itemNo = tokens[1];
                itemName = tokens[2];
                itemQty = tokens[3];
                itemPrice = tokens[4];
                status = tokens[5];


                bw.write("Order No: [" + orderNo + "]" + " Item No: [" + itemNo + "]" + " Back Order No: [" + itemQty + "]");
                bw.newLine();
                bw.flush();
                bw.close();
            }

            System.out.println("Successful add to file!");

        } else if (choice.equalsIgnoreCase("n")) {

            System.out.println("Error");
        }

    } catch (Exception e) {

        System.out.println("Error");
    }

}

Is there any error because it seems like I couldn't find out the problem or did i override it everytime i run? Or should i change the variable name?

Answer 1

You're consuming the BufferedReader br input twice.

First time you successfully print the entire input file to the screen.

But second time (when you try to write) your code fail to read it again, because you have already reached the end of file.

You should close and reopen it, I strongly suggest to have a look at Java try-with-resource statement .

Aside of this problem, I also suggest to create the BufferedWriter bw only when the user answer "yes" to the question (because if your user answer "no" you just create a useless empty file).