java - 文本文件写入后为空。获取索引越界

Question

代码要求用户输入商品名称、价格和数量。我看到它创建了一个文件，但里面没有字符串？缓冲区有问题吗？提前致谢，

用户输入:输入商品名称:商品1输入商品价格 $14输入商品数量:3您想要另一件商品吗？是(y)或否(n)n

代码:

while(userInput.charAt(0)!='n'){
    System.out.print("Enter item name: ");
    itemName = kybd.nextLine();
    PrintWriter out0 = new PrintWriter(new BufferedWriter(new FileWriter("registryCopy.txt", true)));

    System.out.print("Enter item price $");
    price = kybd.nextLine();
    PrintWriter out1 = new PrintWriter(new BufferedWriter(new FileWriter("registryCopy.txt", true)));

    System.out.print("Enter item quantity: ");
    quantity = kybd.nextLine();
    PrintWriter out2 = new PrintWriter(new BufferedWriter(new FileWriter("registryCopy.txt", true)));


    System.out.print("Do you want another item? Yes(y) or No(n)");
    userInput= kybd.next();
    }//end of whileLoop

编辑后仍然相同 - 文件内没有字符串:

while(userInput.charAt(0)!='n'){
        PrintWriter out0 = new PrintWriter(new BufferedWriter(new FileWriter("registryCopy.txt", true)));

    System.out.print("Enter item name: ");
    itemName = kybd.nextLine();
    out0.println(itemName);

update2: 好的，最后是刷新 out0.flush();我的输出是:item1//nextline，price//nextline，quantity//nextLine ...我如何使其保持在同一行，以便稍后可以使用hasNext进行一些操作？

更新3:获取indexOutOfBound。文件保存成功后。我打开该文件来执行以下任务:查找每个项目的总 cost、totalCount 和总和。不知道为什么我会越界。错误指出totalCost =+ Double.parseDouble(index[1].trim());源代码:

Scanner data = new Scanner(new File("registryCopy.txt"));

    while(data.hasNext()){
        String line = data.nextLine();
        System.out.println(line);

        String[] index = line.split("\\t");
        totalCost += Double.parseDouble(index[1].trim());
        totalCount += Integer.parseInt(index[2].trim());

        sum = totalCost/totalCount;

    }

Answer 1

您不是写此信:

PrintWriter out0 = new PrintWriter(new BufferedWriter(new FileWriter("registryCopy.txt", true)));

(或您的其他两位作家)，但只是打开它准备写作。尝试写入它并刷新/关闭它。

查看this SO question/answer有关如何写入文件的更多信息。