線程“main”中的異常 java.lang.NumberFormatException：對於輸入字符串：“38”

Question

對於我幾乎准備好的作業，但似乎無法克服錯誤..文件 items.txt 數據

12345,Ballpeen Hammer,25,18.75

56789,十字螺絲刀,120,10.95

24680,爪錘,35,15.98

13579,套筒扳手,48,20.35

28967,六角扳手,70,19.98

文件activity.txt數據

D,12345,0

R,12345,100

S,12345,45

我一次又一次收到的錯誤告訴我錯誤

                       Exception in thread "main" java.lang.NumberFormatException: For input string: " 38"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:569)
at java.lang.Integer.parseInt(Integer.java:615)
at InventoryItemTest.main(InventoryItemTest.java:21)

C:\\Users\\Noah\\AppData\\Local\\NetBeans\\Cache\\8.2\\executor-snippets\\run.xml:53：Java 返回：1 BUILD FAILED（總時間：0 秒）

不工作的代碼

    import java.io.*;
    import java.text.NumberFormat;
    import java.time.format.DateTimeFormatter;
    import java.util.Calendar;
    import java.util.Scanner;

     public class InventoryItemTest {
     private static final int INVENTORY_SIZE=100;
     public static void main(String[] args)
            {
               InventoryItem[] inventoryItems= new 
               InventoryItem[INVENTORY_SIZE];
                        int i= 0;
                 //Process the file
                 try {
                                                                                          Scanner scanfile = new Scanner(new File("items.txt"));

        while (scanfile.hasNextLine())
        {
            String[] lines = scanfile.nextLine().split(",");
            if(Integer.parseInt(lines[0])>=20000 && Integer.parseInt(lines[0])<=79999) { 
                inventoryItems[i] = new InventoryItem(Integer.parseInt(lines[0]), lines[1], Integer.parseInt(lines[2]), Double.parseDouble(lines[3]));
                i++;
           }
        }
        System.out.println(i+" items has been created.");
        scanfile.close();
    }
    catch (FileNotFoundException ex)
    {
        System.err.println("FILE NOT FOUND!!!!");
    }

    try
    {
        int processedCount=0,skippedCount=0;
        Scanner scanFile = new Scanner(new File("activity.txt"));

        while (scanFile.hasNextLine())
        {
            String[] tokens = scanFile.nextLine().split(",");
            int id = Integer.parseInt(tokens[1]);
            System.out.println(id);
            int q = Integer.parseInt(tokens[2]);
            for (int j = 0; j <i ; j++) {
                if(id==inventoryItems[j].getItemNumber())
                {
                    processedCount++;
                    switch (tokens[0])
                    {
                        case "D":
                            inventoryItems[j].setQuantity(q);
                            break;
                        case "R":
                            inventoryItems[j].receiveItems(q);
                            break;
                        case "S":
                            inventoryItems[j].shipItems(q);
                            break;
                    }
                }
                skippedCount++;
            }
        }
        System.out.println("Total Number of received Process: "+processedCount);
        System.out.println("Number of records skipped: "+skippedCount);
        scanFile.close();
        PrintWriter writer = new PrintWriter(new FileWriter("report.txt"));
        //Preparing Report
        double grandTotal=0;
        double value =0;

        writer.println("Joe E. Bagadonuts for the Albatross Company, Ltd.\nPrepared On: "+ Calendar.getInstance().getTime());
        writer.println("\t\tI N V E N T O R Y  R E P O R T\nInventory Item");
        writer.println(String.format("%5s %19s %10s %10s %10s","Number","Description","Quantity","Unit Price","Value"));
        writer.println(String.format("%5s %19s %10s %10s %10s","------","-----------","--------","----------","------"));
        for (int j = 0; j <i ; j++) {
            value = inventoryItems[j].getQuantity()*inventoryItems[j].getUnitCost();
            grandTotal+=value;
            writer.println(String.format("%5s %19s %10s %11s %11s",inventoryItems[j].getItemNumber(),inventoryItems[j].getDescription(),inventoryItems[j].getQuantity(),NumberFormat.getCurrencyInstance().format(inventoryItems[j].getUnitCost()),NumberFormat.getCurrencyInstance().format(value)));

        }
        writer.println(String.format("%5s %19s %10s %10s %10s"," "," "," ","","==================="));
        writer.println(String.format("%5s %19s %10s %11s %11s"," "," "," ","Total ", NumberFormat.getCurrencyInstance().format(grandTotal)));

        writer.close();
    }
    catch (FileNotFoundException ex)
    {
        System.err.println("File not found...");
    } catch (IOException e) {
        System.err.println("Error in creating report");
    }
}

}

Answer 1

您收到該異常是因為您嘗試解析的數字有空格。 trim()是java中的一個函數，用於去除字符串前后的空格。 閱讀 本文以了解有關修剪的更多信息。

import java.io.*;
import java.text.NumberFormat;
import java.time.format.DateTimeFormatter;
import java.util.Calendar;
import java.util.Scanner;

public class InventoryItemTest {
    private static final int INVENTORY_SIZE=100;
    public static void main(String[] args)
    {
        InventoryItem[] inventoryItems= new
                InventoryItem[INVENTORY_SIZE];
        int i= 0;
        //Process the file
        try {
            Scanner scanfile = new Scanner(new File("items.txt"));

            while (scanfile.hasNextLine())
            {
                String[] lines = scanfile.nextLine().split(",");
                int i1 = Integer.parseInt(lines[0].trim());
                if(i1>=20000 && i1<=79999) {
                    inventoryItems[i] = new InventoryItem(i1, lines[1], Integer.parseInt(lines[2].trim()), Double.parseDouble(lines[3].trim()));
                    i++;
                }
            }
            System.out.println(i+" items has been created.");
            scanfile.close();
        }
        catch (FileNotFoundException ex)
        {
            System.err.println("FILE NOT FOUND!!!!");
        }

        try
        {
            int processedCount=0,skippedCount=0;
            Scanner scanFile = new Scanner(new File("activity.txt"));

            while (scanFile.hasNextLine())
            {
                String[] tokens = scanFile.nextLine().split(",");
                int id = Integer.parseInt(tokens[1].trim());
                System.out.println(id);
                int q = Integer.parseInt(tokens[2].trim());
                for (int j = 0; j <i ; j++) {
                    if(id==inventoryItems[j].getItemNumber())
                    {
                        processedCount++;
                        switch (tokens[0])
                        {
                            case "D":
                                inventoryItems[j].setQuantity(q);
                                break;
                            case "R":
                                inventoryItems[j].receiveItems(q);
                                break;
                            case "S":
                                inventoryItems[j].shipItems(q);
                                break;
                        }
                    }
                    skippedCount++;
                }
            }
            System.out.println("Total Number of received Process: "+processedCount);
            System.out.println("Number of records skipped: "+skippedCount);
            scanFile.close();
            PrintWriter writer = new PrintWriter(new FileWriter("report.txt"));
            //Preparing Report
            double grandTotal=0;
            double value =0;

            writer.println("Joe E. Bagadonuts for the Albatross Company, Ltd.\nPrepared On: "+ Calendar.getInstance().getTime());
            writer.println("\t\tI N V E N T O R Y  R E P O R T\nInventory Item");
            writer.println(String.format("%5s %19s %10s %10s %10s","Number","Description","Quantity","Unit Price","Value"));
            writer.println(String.format("%5s %19s %10s %10s %10s","------","-----------","--------","----------","------"));
            for (int j = 0; j <i ; j++) {
                value = inventoryItems[j].getQuantity()*inventoryItems[j].getUnitCost();
                grandTotal+=value;
                writer.println(String.format("%5s %19s %10s %11s %11s",inventoryItems[j].getItemNumber(),inventoryItems[j].getDescription(),inventoryItems[j].getQuantity(),NumberFormat.getCurrencyInstance().format(inventoryItems[j].getUnitCost()),NumberFormat.getCurrencyInstance().format(value)));

            }
            writer.println(String.format("%5s %19s %10s %10s %10s"," "," "," ","","==================="));
            writer.println(String.format("%5s %19s %10s %11s %11s"," "," "," ","Total ", NumberFormat.getCurrencyInstance().format(grandTotal)));

            writer.close();
        }
        catch (FileNotFoundException ex)
        {
            System.err.println("File not found...");
        } catch (IOException e) {
            System.err.println("Error in creating report");
        }
    }

Answer 2

在讀取 items.txt 時，在 InventoryItemTest 中調用 parseInt 時嘗試使用以下方法。

Integer getIntVal(String val){
 return val!=null ? Integer.parseInt(val.trim()) : null;
}

例如：

if(getIntVal(lines[0])>=20000 && getIntVal(lines[0])<=79999) { 
                inventoryItems[i] = new InventoryItem(getIntVal(lines[0]), lines[1], getIntVal(lines[2]), Double.parseDouble(lines[3]));
                i++;
           } 

Answer 3

在您訪問 lines[] 數組的任何地方使用 trim()。

 if (Integer.parseInt(lines[0].trim().trim()) >= 20000 && Integer.parseInt(lines[0].trim()) <= 79999)
 {
      inventoryItems[i] = new InventoryItem(Integer.parseInt(lines[0].trim()), lines[1].trim(), Integer.parseInt(lines[2].trim()), Double.parseDouble(lines[3].trim()));
      i++;
 }