在Java中读取CSV文件时出现NumberFormatException

Question

I'm beginner in java and kinda stuck in these two problems so I'm trying to let the program read from a CSV file line by line.

So in the file I have first row as String and the column is double. So the problem is when it read first line It's reading the titles as double and it gives me an error.

By the way it is CSV file

The error i got are these below Exception in thread "main" java.lang.NumberFormatException: For input string: "CLOSE" This is first error

Second error >> at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecima‌​l.java:1222) –

Third error >> at java.lang.Double.parseDouble(Double.java:510)

Forth error >>> at AlgorithmTrader.ReadInputData(AlgorithmTrader.java:63)

Fifth Error >> at AlgorithmTrader.Run(AlgorithmTrader.java:16)

Last error >> SimpleAlgorithmTradingPlatform.main(SimpleAlgorithmTradingPl‌​atform.java:15)

So the first row in the file has TIMESTAMP | Close | High | Low | open | volume and under each of those row there is numbers as double except volume has integer numbers

Your suggestion will appreciated. Thanks

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Scanner;

public class AlgorithmTrader {

    public void Run() {

        ReadInputData();
    }

    public void ReadInputData() {

        // create object of scanner class for user input
        Scanner scan = new Scanner(System.in);
        // declare file name for input file
        String inputFileName = "";

        // input from user for input file
        System.out.print("Enter Input File Name: ");
        inputFileName = scan.nextLine();
        try {
            PrintWriter pw = new PrintWriter("output.csv");// to open the file

            // create a new file
            File file = new File(inputFileName);
            // create a new scanner object to read file
            Scanner readFile = new Scanner(file);

            // for each line data
            String line = "";

            line = readFile.nextLine();//skip the first line

            while (readFile.hasNextLine()) {

                readFile.nextLine();
                // pass file to scanner again
                readFile = new Scanner(file);

                ArrayList<String> list = new ArrayList<String>();

                // read stock data line by line

                while (readFile.hasNextLine()) {
                    // read line from file
                    line = readFile.nextLine();
                    // split line data into tokens
                    String result[] = line.split(",");

                    // variables to create a Stock object

                    String timestamp = result[0];
                    double close = Double.parseDouble(result[1]);
                    double high = Double.parseDouble(result[2]);
                    double low = Double.parseDouble(result[3]);
                    double open = Double.parseDouble(result[4]);
                    int volume = Integer.parseInt(result[5]);

                    // store data into ArrayList
                    list.add(readFile.next());
                    pw.print(list.add(readFile.next()));

                    Stock stock = new Stock(timestamp, close, high, low, open, volume);
                }// end of while to read file

                //close readFile object
                readFile.close();
                pw.close();//close file
            }
        } catch (FileNotFoundException e1) {

            System.out.println(" not found.\n");
            System.exit(0);
        } catch (IOException e2) {
            System.out.println("File can't be read\n");
        }
    }
}

I have another file Stock class

public class Stock {

    String timestamp;

    double close;
    double high;
    double low;
    double open;
    int volume;

    Stock(String t, double c, double h, double l, double o, int v) {
        timestamp = t;
        close = c;
        high = h;
        low = l;
        open = o;
        volume = v;
    }

    public void settimestamp(String t) {
        this.timestamp = t;
    }

    public void setclose(double c) {
        this.close = c;
    }

    public void sethigh(double h) {
        this.high = h;
    }

    public void setopen(double o) {
        this.open = o;
    }

    public void setvolume(int v) {
        this.volume = v;
    }

    public String gettimestamp() {
        return timestamp;
    }

    public double close() {
        return close;
    }

    public double high() {
        return high;
    }

    public int volume() {
        return volume;
    }
}

And The main method in another file as well

import java.text.DecimalFormat;

public class SimpleAlgorithmTradingPlatform {

    public static void main(String[] args) {

        DecimalFormat fmt = new DecimalFormat("#0.00"); // to get the      DecimalFormat

        AlgorithmTrader test = new AlgorithmTrader();

        test.Run();
    }
}

Answer 1

You are you having NumberFormatException because here

line = readFile.nextLine();//skip the first line 

you are not skipping first line. You'd better use BufferedReader instead of Scanner after getting file name. I have corrected you code a bit.

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

public class AlgorithmTrader {

    public void Run() {
        ReadInputData();
    }

    public void ReadInputData() {

        // create object of scanner class for user input
        Scanner scan = new Scanner(System.in);
        // declare file name for input file
        String inputFileName = "";

        // input from user for input file
        System.out.print("Enter Input File Name: ");
        inputFileName = scan.nextLine();

        // create a new file
        File csvFile = new File(inputFileName);
        String line;
        ArrayList<Stock> list = new ArrayList<>();

        try (BufferedReader br = new BufferedReader(new FileReader(csvFile))) {

            System.out.println("Reading file " + csvFile);

            System.out.println("Skipping title of the CSV file");
            // Skip first line because it is title
            br.readLine();

            System.out.println("Converting line to Stock");

            while ((line = br.readLine()) != null) {

                String result[] = line.split(",");
                String timestamp = result[0];
                double close = Double.parseDouble(result[1]);
                double high = Double.parseDouble(result[2]);
                double low = Double.parseDouble(result[3]);
                double open = Double.parseDouble(result[4]);
                int volume = Integer.parseInt(result[5]);

                list.add(new Stock(timestamp, close, high, low, open, volume));
            }

            System.out.println("Done");

        } catch (FileNotFoundException e1) {
            System.out.println(" not found.");
            System.exit(0);
        } catch (IOException e2) {
            System.out.println("File can't be read");
        }
    }
}

Answer 2

It would be nice to see a fictional example of the contents within your CSV file but please spare us any additional comments. ;)

It looks like your errors (and probably all of them) are most likely coming from your Stock Class. That's for another posted question however your getters and setters need attention. Some are missing as well but perhaps this is by choice.

You should be able to carry out this task with one Scanner object and one while loop. Use the same Scanner object for User input and file reading, it's reinitialized anyways.

The code below is one way to do it:

ArrayList<String> list = new ArrayList<>();
// create object of scanner class for user input
// and File Reading.
Scanner scan = new Scanner(System.in);
// declare file name for input file
String inputFileName = "";
// input from User for input file name.
System.out.print("Enter Input File Name: ");
inputFileName = scan.nextLine();

String tableHeader = "";
try {
    // create a new file with PrintWriter in a 
    PrintWriter pw = new PrintWriter("output.csv"); 
    File file = new File(inputFileName);
    // Does the file to read exist?
    if (!file.exists()) {
        System.err.println("File Not Found!\n");
        System.exit(0);
    }   
    // create a new scanner object to read file
    scan = new Scanner(file);
    // for each line data
    String line = "";
    tableHeader = scan.nextLine();
    String newline = System.getProperty("line.separator");
    // Print the Table Header to our new file.
    pw.print(tableHeader + newline);

    while (scan.hasNextLine()) {
        line = scan.nextLine();
        // Make sure we don't deal with a blank line.
        if (line.equals("") || line.isEmpty()) {
            continue;
        }
        // split line data into a String Array.
        // Not sure if there is a space after 
        // comma delimiter or not but I'm guessing
        // there is. If not then remove the space.
        String result[] = line.split(", ");
        // variables to create a Stock object
        String timestamp = "";
        double close = 0.0;
        double high = 0.0;
        double low = 0.0;
        double open = 0.0;
        int volume = 0;

        // Make sure there are enough array elements 
        // from our split string to fullfil all our 
        // variables. Maybe some data is missing.
        int resLen = result.length;
        if (resLen > 0) {
            if (resLen >= 1) { timestamp = result[0]; }
            if (resLen >= 2) { close = Double.parseDouble(result[1]); }
            if (resLen >= 3) { high = Double.parseDouble(result[2]); }
            if (resLen >= 4) { low = Double.parseDouble(result[3]); }
            if (resLen >= 5) { open = Double.parseDouble(result[4]); }
            if (resLen >= 6) { volume = Integer.parseInt(result[5]); }
        }
        // store data into ArrayList.
        // Convert the result Array to a decent readable string.
        String resString = Arrays.toString(result).replace("[", "").replace("]", "");
        list.add(resString);
        // Print the string to our output.csv file.
        pw.print(resString + System.getProperty("line.separator"));

        //Stock stock = new Stock(timestamp, close, high, low, open, volume);
    }   
    //close file
    scan.close();
    pw.close();
} 
catch (IOException ex ){
    System.err.println("Can Not Read File!\n" + ex.getMessage() + "\n");
    System.exit(0);
}

// Example to show that the ArrayList actually 
// contains something....
// Print data to Console Window.
tableHeader = tableHeader.replace(" | ", "\t");
tableHeader = "\n" + tableHeader.substring(0, 10) + "\t" + tableHeader.substring(10);
System.out.println(tableHeader);
for (int i = 0; i < list.size(); i++) {
    System.out.println(list.get(i).replace(", ", "\t"));
}