在Java

Question

我正在编写一些代码来从文本板读取静态库存号。我跑了它看看有什么问题，我似乎无法修复这个找不到符号错误。

import java.io.*;
import java.util.*;

public class StockMarket
{
    public static void main(String[] args) throws IOException
    {

        Scanner keyboard = new Scanner(System.in);

        System.out.println("Enter the filename: ");
        String filename = keyboard.nextLine();

        File file = new File(filename);
        Scanner inputFile = new Scanner(file);

        while (inputFile.hasNext())
        {
            checkValidity();
        }

        inputFile.close();

    }

    public static boolean checkValidity()
    {

    String line = inputFile.nextLine();
    double numberOfShares = inputFile.nextDouble();
    double buyPricePerShare = inputFile.nextDouble();
    double buyComissionRate = inputFile.nextDouble();
    double sellPricePerShare = inputFile.nextDouble();
    double sellComissionRate = inputFile.nextDouble();

    }

}

Answer 1

您的checkValidity()方法遇到的问题很少，如下所述：

（1）您的 Scanner对象范围仅存在于main方法中，因此将该对象传递给checkValidity方法

（2）验证checkValidity方法

中的输入

（3）您的 checkValidity方法已return类型boolean，因此您需要return boolean值从中，即如果验证成功，则返回true或如果验证失败，则返回false

您可以使用内联注释来引用以下代码：

public static boolean checkValidity(Scanner inputFile) {
        String line = inputFile.nextLine();
        double numberOfShares = inputFile.nextDouble();
        double buyPricePerShare = inputFile.nextDouble();
        double buyComissionRate = inputFile.nextDouble();
        double sellPricePerShare = inputFile.nextDouble();
        double sellComissionRate = inputFile.nextDouble();
        boolean validationSuccess = false;
        //validate your inputs
        // If validations are successful  then set validationSuccess = true;
        return validationSuccess;//return boolean
    }

另外，从scanner传递main()对象，如下所示：

while (inputFile.hasNext()) {
     checkValidity(inputFile);//pass scanner object
}

Answer 2

您的方法checkValidity无效。您尝试访问方法中未知的变量inputFile。你必须传递参数。

public static boolean checkValidity(Scanner inputFile)

{

String line = inputFile.nextLine();
double numberOfShares = inputFile.nextDouble();
double buyPricePerShare = inputFile.nextDouble();
double buyComissionRate = inputFile.nextDouble();
double sellPricePerShare = inputFile.nextDouble();
double sellComissionRate = inputFile.nextDouble();

}