[英]NoSuchElementException when trying to read integers from a file?
[英]Error: NoSuchElementException when trying to read values from file to array
好的。 因此,這是該學期的最后一次硬件作業,我在程序中忽略了很大一部分,因為這是我似乎無法解決的唯一問題。 我正在設置FileInputStream並使用for循環將值讀入數組,就像我過去所做的一樣,沒有任何問題。 由於某種原因,我遇到了這個異常,無法解決。 我已經研究了圍繞此異常的許多其他線程,但同樣,似乎也無法弄清楚。 請暫停。
這是代碼,它可以編譯;
import java.util.*;
import java.io.*;
public class CollinDunn_1_10 {
// Declare constants
static final int MAX_EMPLOY = 30;
static final String TAB = "\t";
static final String NL = "\n";
static final double IRA_INVEST = .08;
static final double FEDERAL_WITH = .18;
static final double STATE_WITH = .045;
static final double SAVINGS = .10;
public static void main (String [] args) throws Exception {
// I/O String references
final String INPUT = "CollinDunn_1_10_Input.txt";
final String OUTPUT = "CollinDunn_1_10_Output.txt";
// Declare variables
// One-dimensional array for storing employee names
String [] names = new String [MAX_EMPLOY];
// Two-dimensional array for storing employee pay data
// [0] hours worked [1] pay rate [2] gross pay [3] net pay
// [4] savings amount [5] IRA amount [6] taxs withheld
double [][] payInfo = new double [MAX_EMPLOY][6];
// Set up I/O
FileInputStream inputDataFile = new FileInputStream(INPUT);
Scanner inputFile = new Scanner(inputDataFile);
FileWriter outputDataFile = new FileWriter(OUTPUT);
PrintWriter outputFile = new PrintWriter(outputDataFile);
// Read data from the file
readData(inputFile, payInfo, names);
// Test printing to see if values are stored - REMOVE
for (int i = 0; i < MAX_EMPLOY; i++) {
System.out.print(names[i] + TAB + payInfo[i][0] + TAB + payInfo[i][1]);
}
} // End main
// Method for reading file data into the file.
// Data is sorted as (number of hours) (pay rate) (name)
public static void readData (Scanner inputFile, double [][] payInfo, String [] names) {
for (int i = 0; i < MAX_EMPLOY; i++) {
payInfo [i][0] = inputFile.nextDouble();
payInfo [i][1] = inputFile.nextDouble();
names [i] = inputFile.nextLine();
} // End For
return;
} // End readData
} // End Class
*文本文件中的字段為:(小時)(薪水)(名稱)
50.00 10.60輕卡倫
52.00 10.80法根·伯特·托德
62.00 12.24安特里姆·福雷斯特N *
The Exception and stack trace:
Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:862)
at java.util.Scanner.next(Scanner.java:1485)
at java.util.Scanner.nextDouble(Scanner.java:2413)
at CollinDunn_1_10.readData(CollinDunn_1_10.java:56)
at CollinDunn_1_10.main(CollinDunn_1_10.java:42)
在嘗試檢索值之前,您永遠不會檢查是否有要檢索的值(查找Scanner.hasNextDouble)。 由於您的for循環經過MAX_EMPLOY迭代,因此只要您的輸入文件包含少於MAX_EMPLOY行的數據,就會發生此異常。
您應該每次檢查表或文件中是否包含正確數量的元素,或者它們是否足夠大。 代碼應如下所示:
public static void readData (Scanner inputFile, double [][] payInfo, String [] names) {
Integer payInfoLenght = payInfo.lenght;
Integer namesLenght = names.lenght;
if (MAX_EMPLOY > payInfoLenght || MAX_EMPLOY > namesLenght) {
System.out.println("Wrong size of tabels");
} else {
for (int i = 0; i < MAX_EMPLOY; i++) {
if (inputFile.hasNextDouble()) {
payInfo [i][0] = inputFile.nextDouble();
}
if (inputFile.hasNextDouble()) {
payInfo [i][1] = inputFile.nextDouble();
}
if (inputFile.hasNextLine()) {
names [i] = inputFile.nextLine();
}
}
}
}
而且您不需要“返回”; 在此方法的末尾,因為此方法沒有任何回報。 這是“無效”的方法。
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