This是我的任务：
以下是我的问题：
线程“main”中的异常java.lang.NumberFormatException：empty String at sun.misc.FloatingDecimal.readJavaFormatString（FloatingDecimal.java:1012） 在java.lang.Double.parseDouble（Double.java:527） 在extracredit.Main.readData（Main.java:72） 在extracredit.Main.main（Main.java:27）
到目前为止，这是我的代码：
import java.io.*;
import javax.swing.JOptionPane;
import java.util.*;
import java.util.StringTokenizer;
public class Main {
public static void main(String[] args) throws IOException {
String fname = "data.txt"; //Read in the data file for use in the array
String pass= JOptionPane.showInputDialog("Please enter the " +
"password to continue:"); /*Have the user enter the password to
access the file. */
checkPass(pass); // Verify that the password is correct before continuing.
readData (fname); // Read data, print output and save output file.
}
private static void checkPass (String pass)
{
String password= "INF260";
int passCount= 0;
if (pass.equals(password)) {
System.out.println("The password is correct. Continuing...");
}
else {
do {
pass= JOptionPane.showInputDialog("Please re-enter the" +
"password:");
passCount++;
} while (!pass.equals(password) && passCount < 2);
if (!pass.equals(password)) {
System.out.println("You have tried to enter the " +
"password too many times. Exiting...");
System.exit(0);
}
else {
System.out.println("The password is correct. Continuing...");
}
}
}
public static void readData (String data) throws IOException{
FileReader inputData= new FileReader (data);
BufferedReader findNum= new BufferedReader (inputData);
String str= findNum.readLine ();
int count=-1;
int countNum= 0;
double total= 0;
double min= 0;
double max= 0;
double average= 0;
FileWriter writeFile = new FileWriter("sales.txt");
PrintWriter printFile = new PrintWriter(writeFile);
while (str != null)
{
double num= Double.parseDouble (str);
if (count == 0){
countNum++; // counter of Reciepts to use
}
str = findNum.readLine();
}
double [][] input = new double [countNum][10];
total= getCurrentTotal(input); /*This will get the total
from the method getCurrentTotal.*/
min= getCurrentMin(input); /*This will get the minimum value from
the method getCurrentMin.*/
max= getCurrentMax (input); /*This will get the maximum value from
the method getCurrentMax.*/
average= (total / countNum); //Calculate the average.
System.out.println("The List of Today's Sales:");
for (int row = 0; row < input.length; row++){
System.out.println ();
System.out.println("Customer " + row + "\t");
for (int column = 0; column < input[row].length; column++){
if (input [row].length < 10){
System.out.println(input[row][column] + "\t");
str = findNum.readLine();
}
else{
System.out.println ("There are too many receipts" +
" for one Customer.\n");
System.exit (0);
}
}
}
System.out.println ("There are " + countNum + "receipts in the list.");
/*This will print the total of receipts in the list.*/
System.out.println ("The total of today's sales is $" + total); /*
This will print the total of the sales for the day.*/
System.out.println ("The average of today's sales is $" + average); /*
This will print the average sale total.*/
System.out.println ("The highest receipt is $" + max); /* This will print
the highest sale.*/
System.out.println ("The lowest receipt is $" + min); /* This will print
the lowest sale.*/
Date date = new Date();
System.out.println ("\n The current time is:" + date.toString()); /* This
will print the current date and time */
}
public static double getCurrentTotal (double [][] input){
double totalAmount = 0;
for (int row = 0; row < input.length; row++){
for (int column = 0; column < input [row].length; column++){
totalAmount += input [row][column];
}
}
return totalAmount;
}
public static double getCurrentMin (double [][] input) {
double currentMin = input[0][0];
for (int row = 0; row < input.length; row++){
for (int column = 0; column < input [row].length; column++){
if (currentMin > input[row][column])
currentMin = input[row][column];
}
}
return currentMin;
}
public static double getCurrentMax (double [][] input){
double currentMax = input[0][0];
for (int row = 0; row < input.length; row++){
for (int column = 0; column < input [row].length; column++){
if (currentMax < input[row][column]){
currentMax = input[row][column];
}
}
}
return currentMax;
}
}
答案 0 :(得分：3)
最佳解决方案是：
答案 1 :(得分：1)
// from your main method
String fname = "data.txt";
readData (fname);
// the method being called
public static void readData (String data[][]){
BufferedReader br = new BufferedReader(new FileReader(data));
我们在这里不兼容。
所有这三个应该是相同的数据类型。
如何将每个“收据”与零分开（如上图中的图片链接所示）？
你不必。您必须从该文件中读取其中的零 我建议你写一个像这样的方法：
public double [] readOneReceipt（BufferedReader reader）;
此方法
如何将输出写入单独的文件？
使用java.io.FileWriter
这个IMO中最困难的事实是你被告知要将数据存储在一个二维数组中，但是在你读取数据之前你没有确切的数量。 这意味着您要么使用临时动态结构，要么读取文件两次 - 一次查找有多少收据以便您可以制作数组，然后再次实际读取收据数据。