java - 读取文件以打印到屏幕

Question

我有一个文件 Inventory.txt，我正在尝试将其打印到屏幕上。文件中的每一行都进入一个对象数组。我的代码编译时没有错误，但是当我运行它时，屏幕上什么也没有打印。我使用 Mac 和 TextEdit/Terminal。

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

public class VendingMachineSimulator
{
    to be imported
    public static void main(String[] args) throws FileNotFoundException 
    {

        File InventoryFile = new File("Inventory.txt");
        Scanner input = new Scanner(InventoryFile);

        //This code block will count the number of lines(products) are in the text file
        int counter = 0;
        while (input.hasNextLine())
        {
            counter = counter + 1;
        }

        Inventory[] InventoryObject = new Inventory[counter];
        String line = "";


        for (int i = 0; i < counter; i++)
        {
            String[] ProductArray = line.split("-");

            InventoryObject[i] = new Inventory(Integer.valueOf(ProductArray[0]), ProductArray[1], ProductArray[2], 
                                               ProductArray[3],Double.valueOf(ProductArray[4]), ProductArray[5], 
                                               Integer.valueOf(ProductArray[6]));
        } 

        for (int i = 0; i < counter; i++)
        {
            System.out.println();
            InventoryObject[i].PrintInventory();
        } 


    }

    public static void PrintMenu()
    {
        System.out.println();
        System.out.println("Display Inventory: <1>");
        System.out.println("Display Currency:  <2>");
        System.out.println("Purchase Item:     <3>");
        System.out.println("Exit:              <4>");
        System.out.println();
    }


}

class Inventory
{
    private int ID;
    private String Type;
    private String Name;
    private String PriceText;
    private double Cost;
    private String QuantityText;
    private int StockAmount;

    //Constructor method. values passed to it from the main method. 
    public Inventory(int ID, String Type, String Name, String PriceText, double Cost, String QuantityText, int StockAmount) 
    {
        this.ID = ID;
        this.Type = Type;
        this.Name = Name;
        this.PriceText = PriceText;
        this.Cost = Cost;
        this.QuantityText = QuantityText;
        this.StockAmount = StockAmount;
    }

    public void setID(int ID)
    {
        this.ID = ID;
    }

    public void setType(String Type)
    {
        this.Type = Type;
    }

    public void setName(String Name)
    {
        this.Name = Name;
    }

    public void setPriceText(String PriceText)
    {
        this.PriceText = PriceText;
    }

    public void setCost(double Cost)
    {
        this.Cost = Cost;
    }

    public void setQuantityText(String QuantityText)
    {
        this.QuantityText = QuantityText;
    }

    public void setStockAmount(int StockAmount)
    {
        this.StockAmount = StockAmount;
    }

    public int getID()
    {
        return ID;
    }

    public String getType()
    {
        return Type;
    }

    public String getName()
    {
        return Name;
    }

    public String getPriceText()
    {
        return PriceText;
    }

    public double getCost()
    {
        return Cost;
    }

    public String getQuantityText()
    {
        return QuantityText;
    }

    public int getStockAmount()
    {
        return StockAmount;
    }

    public void PrintInventory()
    {
        System.out.println(ID + " " + Type + " " + Name + " " + PriceText
                           + " " + Cost + " " + QuantityText + " " + StockAmount);
    }




}

Answer 1

你从来没有读过一行，你只是计算它们:

while (input.hasNextLine())
{
    counter = counter + 1;
}

您必须将 line = input.readLine(); 放置在该循环内的某个位置并相应地更改您的逻辑，否则，它将始终停留在 while 循环中。考虑一下何时需要更新或读取计数器。