Question

您好我在读取此项目的CSV文本文件时收到NumberFormatException错误。这是CSV

12345,Left-Handed Bacon Stretcher,125.95,PGH,2
24680,Smoke Shifter,0.98,PGH,48
86420,Pre-dug Post Hole,2.49,ATL,34
25632,Acme Widget,98.29,LOU,342
97531,Anti-Gravity Turbine,895.29,ATL,3
24680,Battery-Powered Battery Charger,252.98,ATL,2
12345,Left-Handed Bacon Stretcher,125.95,LOU,35
97531,Anti-Gravity Turbine,895.29,PHL,8
00000,Glass Hammer,105.90,PGH,8
01020,Inflatable Dartboard,32.95,PGH,453
86420,Pre-dug Post Hole,2.49,LOU,68
86420,Pre-dug Post Hole,2.49,PGH,124
24680,Battery-Powered Battery Charger,252.98,PHL,5

我对将要发生的事情有一个大致的了解。出现错误我相信因为它到达第一行的末尾然后弹出错误

Exception in thread "main" java.lang.NumberFormatException: For input 
string: "2 24680"

这是我到目前为止所做的：

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

public class Prog7
{

    public static void main(String[] args)
    {
        String warehouseID = null;
        String city = null;
        String state = null;
        int partNumber = 0;
        String description = null;
        double price = 0.0;
        int quantity = 0;
        int count = 0;

        int numWarehouse = 4;
        int numParts = 13;
        Scanner warehouseFile = null;
        Scanner partFile = null;

        Warehouse[] warehouse = new Warehouse[10];
        Part[] parts = new Part[20];

        try
        {
            warehouseFile = new Scanner(new File("warehouse.txt"));
            while (warehouseFile.hasNext())
            {
                warehouseID = warehouseFile.next();
                city = warehouseFile.next();
                state = warehouseFile.next();
                warehouse[count] = new Warehouse(warehouseID, city, state);
                count++;
            }

            partFile = new Scanner(new File("parts.txt"));
            partFile.useDelimiter(",");
            while (partFile.hasNext())
            {
                partNumber = Integer.parseInt(partFile.next());
                description = partFile.next();
                price = Double.parseDouble(partFile.next());
                warehouseID = partFile.next();
                quantity = Integer.parseInt(partFile.next());
                parts[count] = new Part(partNumber, description, price, warehouseID, quantity);
                count++;

            }

        }

        catch (FileNotFoundException e)
        {
            System.err.print("warehouse.txt or parts.txt not found");
        }

        for (int i = 0; i < numWarehouse; i++)
        {
            System.out.printf("%5s %5s %5s\n", warehouse[i].getWarehouseID(), warehouse[i].getCity(),
                    warehouse[i].getState());

            for (int j = 0; j < numParts; j++)
            {
                if (parts[j].getWarehouseID().equals(warehouse[i].getWarehouseID()))
                {
                    System.out.printf("%5s %5s %10.2f %5\nd", parts[j].getPartNumber(), parts[j].getDescription(),
                            parts[j].getPrice(), parts[j].getQuantity());

                }

            }
        }

    }

}

我认为它与程序有关，就是读取每个值，但是没有什么可以进入下一行。我有一个尝试过partFile.nextLine（）指令和一个hasNextLine（）while循环，我仍然得到相同的错误。或许我可以用换行符进行操作吗？

Answer 1

我认为问题在于：

        partFile.useDelimiter(",");

您告诉扫描仪只能用逗号分割。一旦到达parts.txt第一行中的最后一项，它就会向前读取，直到找到下一行中的第一个逗号，然后返回2，然后返回行尾，后跟{ {1}}作为下一个项目。

您不仅想要用逗号分割，还想用换行符分割。 useDelimiter采用正则表达式：以下内容告诉扫描程序拆分逗号或换行符的任意组合：

Answer 2

除了Luke Woodward的回答，也许你应该考虑到2018年，而不是1999年。以下代码应该做你正在寻找的东西，知道如何解析一条线移动到它所属的类中。我把它作为构造函数，但它也可以是静态valueOf方法。

Path warehouseFile = Paths.get("warehouse.txt");
Files.lines(warehouseFile)
  .map(Warehouse::new)
  .collect(toList());

static class Warehouse {
  public Warehouse(String line) {...}
}

在项目的CSV文件中读取问题

2 个答案: