![](/img/trans.png)
[英]java.lang.NumberFormatException: empty String [FloatingDecimal]
[英]“java.lang.NumberFormatException: empty String” with a not empty String
我目前正在課外開展個人項目,在閱讀文本文件到鏈表時遇到了一些問題。 當讀到第一雙時,我得到一個
java.lang.NumberFormatException: empty String
錯誤。 我在程序中添加了一條打印行,打印出我想要解析為double的內容,而變量實際上並非空,實際上是一個雙精度數。
就像我上面說的那樣,我添加了一個打印行來打印出我想要解析成雙字符串的字符串,它似乎沒問題。 這是讀入並分割成我正在打印的數組的String:
500.0 % 04/05/2019 % This is paycheck 1 % true % 49.5
我必須將兩個字符串解析為雙精度數,而我只遇到第一個問題。 當我注釋掉第一個被解析的雙子程序時,程序運行沒有問題。 這是從運行到程序的完整輸出
*File loading*
*500.0*
*Exception in thread "main" java.lang.NumberFormatException: empty String*
*at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)*
*at sun.misc.FloatingDecimal.parseDouble(Unknown Source)*
*at java.lang.Double.parseDouble(Unknown Source)*
*at fileHandling.readPaycheck(fileHandling.java:194)*
*at UserMenu.main(UserMenu.java:20)*
問題發生在這行代碼中的“將數組拆分為適當的臨時變量”部分:
payCheckAmount = Double.parseDouble(tempArray[0]);
以下是此方法的代碼
public void readPaycheck(LinkedList<PayCheck> paycheck) throws IOException {
// Declare Variables
Scanner sc = new Scanner(payChecks); // Scanner used to read in from the payChecks text file
String temp; // A string used to hold the data read in from the file temporarily
String[] tempArray; // A String array used to temporarily hold data from the text file
double payCheckAmount; // A double holding the amount of the paycheck
String paycheckDate; // A string holding the date of the paycheck
String description; // A string holding a description of the paycheck
boolean payCheckSplit; // A boolean stating if the paycheck has been split or not
double amountUnSplit; // A double
// A while loop that runs while the text file still has data in it
while (sc.hasNextLine()) {
// Reading in a new line from the paycheck file
temp = sc.nextLine();
// Splitting the line into an array
tempArray = temp.split(" % ");
// Temp output used for testing of the issue at hand
System.out.println(tempArray[0]);
// Splitting the array into its appropriate temp variables
payCheckAmount = Double.parseDouble(tempArray[0]);
paycheckDate = tempArray[1];
description = tempArray[2];
payCheckSplit = Boolean.parseBoolean(tempArray[3]);
amountUnSplit = Double.parseDouble(tempArray[4]);
// putting the temp variables into a temp paycheck object
PayCheck tempCheck = new PayCheck(payCheckAmount, paycheckDate, description, payCheckSplit, amountUnSplit);
paycheck.add(tempCheck);
}
}
編輯:
這是我遇到的問題的最小,完整和可驗證的示例:
import java.io.File;
import java.io.IOException;
import java.util.Scanner;
public class test {
public static void main(String[] args) throws IOException {
// Declare Variables
File payChecks = new File("C:\\Users\\zwtw\\Documents\\paychecks.txt");
Scanner sc = new Scanner(payChecks);
while (sc.hasNextLine()) {
String temp = sc.nextLine();
String[] tempArray = temp.split(" % ");
System.out.println(tempArray[0]);
// Splitting the array into its appropriate temp variables
double payCheckAmount = Double.parseDouble(tempArray[0]);
String paycheckDate = tempArray[1];
String description = tempArray[2];
boolean payCheckSplit = Boolean.parseBoolean(tempArray[3]);
double amountUnSplit = Double.parseDouble(tempArray[4]);
}
}
}
以下是上述代碼中提到的文本文件的內容:
500.0 % 04/05/2019 % This is paycheck 1 % true % 49.5
450.0 % 04/09/2019 % This is paycheck 2 % true % 49.75
您的文本文件可能包含空行。 您可以刪除文本文件中的新行,更改文本文件的創建方式,也可以在閱讀時跳過空行。
這是你跳過空行的方法:
while (sc.hasNextLine()) {
String temp = sc.nextLine();
if (temp.equals("")) { continue; } // <--- notice this line
String[] tempArray = temp.split(" % ");
System.out.println(tempArray[0]);
// Splitting the array into its appropriate temp variables
double payCheckAmount = Double.parseDouble(tempArray[0]);
String paycheckDate = tempArray[1];
String description = tempArray[2];
boolean payCheckSplit = Boolean.parseBoolean(tempArray[3]);
double amountUnSplit = Double.parseDouble(tempArray[4]);
}
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.