Develop Reference

NumberFormatException when reading CSV file in java

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();
}
}

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");
}
}
}

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"));
}

PrintWriter isn't writing the int values into the new file it created

So I'm supposed to read in a .txt file and then write a new one with the numbers backwards. For some reason only the number 0 is being printed in the new file when it should be 987654321987654321.
EDIT:
The input file reads:
123456789123456789
import java.io.*;
import java.util.*;
class Reverb
{
public static void main(String[] args) throws IOException
{
//System.out.println("Enter the name of the file you wish to open and reverse.");
Scanner kb = new Scanner(System.in);
//String s = kb.next();
Scanner inFile = new Scanner(new File("Untitled.txt"));
PrintWriter outFile = new PrintWriter("reversamundo2.txt");
int[] a = new int[18];
int index = 0;
while(inFile.hasNextInt())
{
a[index] = inFile.nextInt();
index++;
}
for(int i = index; i >= 0; i--)
{
outFile.println(a[i]);
}
inFile.close();
outFile.close();
}
}

You want to read character by character instead of a string and then reverse it. You can just read the String and reverse it using StringBuilder. So the code looks like:
Scanner inFile = new Scanner(new File("Untitled.txt"));
PrintWriter outFile = new PrintWriter("reversamundo2.txt");
// Read the first String from the input file.
String line = inFile.next();
// Create a StringBuilder object for that string, reverse it and return a string.
String reverse = new StringBuilder(line).reverse().toString();
// Print the reversed string to a new file.
outFile.print(reverse);

Input a text file in a two dimensional array with doubles

I'm new in Java.
I want to input a text file and create from it a two dimensional array the input is
like this
12,242 323,2324
23,4434 23,4534
23,434 56,3434
....
34,434 43,3443
I have tried
import java.util.Scanner;
import java.io.File;
import java.io.IOException;
public class InputText {
/**
* #param args the command line arguments
* #throws java.io.IOException
*/
public static void main(String[] args) throws IOException {
int i=0;
File file;
file = new File("file.txt");
Scanner read=new Scanner(file);
while (read.hasNextLine()) {
String line=read.nextLine();
System.out.println(line);
}
}
}
which gives me the input but I cannot insert this in an array I tried different ways like splitting it.
Any suggestions?
Sorry for not being clear. The input i mentioned is doubles seperated by spaces. Also the format i gave you is what i get after i run the part of the programm i wrote. What i see in the text file is the numbers seperated by spaces. I tried to implement your suggestion but nothing seemed to work. I'm really lost here....

If you want to split a line to two numbers you can use
string[] numbers = line.split("\\s+");
If you want to read a double with comma
NumberFormat format = NumberFormat.getInstance(Locale.FRANCE);
...
double d1 = format.parse(numbers[0]).doubleValue();
double d2 = format.parse(numbers[1]).doubleValue();
Personally i prefer to use scanner. In that case create it with
Scanner scanner = new Scanner(file);
while (scanner.hasNextLine()) {
Scanner scanner2 = new Scanner(scanner.nextLine()).useLocale(Locale.FRANCE);
if (!scanner2.hasNextDouble()){
System.out.println("Do not have a pair");
continue;
}
double d1 = scanner2.nextDouble();
if (!scanner2.hasNextDouble()){
System.out.println("Do not have a pair");
continue;
}
double d2 = scanner2.nextDouble();
//do something
}

After reading the line.. you will have to again split the string on ','. The split string need to be converted into interger. YOu can see as below:
import java.util.Scanner;
import java.io.File;
import java.io.IOException;
public class InputText {
/**
* #param args the command line arguments
* #throws java.io.IOException
*/
public static void main(String[] args) throws IOException {
int i = 0;
File file;
file = new File("file.txt");
Scanner read = new Scanner(file);
while (read.hasNextLine()) {
String line = read.nextLine();
String[] numbers = line.split(",");
for (i = 0; i < numbers.lenght; i++) {
String numStr = numbers[i];
String x=numStr.replaceAll("\\s+",""); //eleminate the space in any.
Double num = Double.valueOf(x);
System.out.println(" num is: " + num); //Here you can store the number in array.
}
}
}
}

Try to use something like that(add also try catch statement)
String line = "";
br = new BufferedReader(new FileReader("file.txt"));
int i=0;
while ((line = br.readLine()) != null) {
// use comma as separator
String[] lineArray= line.split(",");
for(int j=0;j<lineArray.length;j++){
my2DArray[i][j] = lineArray[j];
}
i++;
}
for(int i=0;i<my2DArray[0].length;i++){
for(int j=0;j<my2DArray[1].length;j++){
System.out.print(my2DArray[i][j] + " ");
}
}

JAVA Filling a 2D array from a file with an unknown amount of rows

I am trying to figure out how to make a program that reads data from a text file, and fills a Jtable with it, I will need to be able to search the table, and do some calculations with the numbers.
A row in the text file would contain:
name, country, gender, age, weight
The number of rows is unknown (I need to count the number of rows).
This is what I tried, but it seems to crash. I need to count the # of rows, and then fill the array with the content from the rows.
package Jone;
import java.io.*;
import java.util.*;
public class Jone {
public static void main (String [] args)throws IOException{
int rows = 0;
Scanner file = new Scanner (new File("data.txt"));
while (file.hasNextLine()){rows++;}
Object[][] data = new Object[rows][5];
System.out.print(rows);
file.nextLine();
for(int i = 0;i<rows;i++)
{
String str = file.nextLine();
String[] tokens= str.split(",");
for (int j = 0;j<5;j++)
{
data[i][j] = tokens[j];
System.out.print(data[i][j]);
System.out.print(" ");
}
}
file.close();
}
}

change your code as follows
package Jone;
import java.io.*;
import java.util.*;
public class Jone {
public static void main (String [] args)throws IOException{
try{
int rows = 0;
Scanner file = new Scanner (new File("data.txt"));
while (file.hasNextLine())
{
rows++;
file.nextLine();
}
file = new Scanner (new File("data.txt"));
System.out.println(rows);
Object[][] data = new Object[rows][5];
for(int i = 0;i<rows;i++)
{
String str = file.nextLine();
String[] tokens= str.split(",");
for (int j = 0;j<5;j++)
{
data[i][j] = tokens[j];
System.out.print(data[i][j]);
System.out.print(" ");
}
}
file.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}

You create an array with 0 rows and then you try to access the empty array dimension.
Also I suppose you should reset the pointer of the scanner after counting the rows.
ArrayList should be more useful for your goal.

class Person {
String name, country, gender;
int age;
double weight;
public Person(String n, String c, String g, int a, double w) {
name = n;
country = c;
gender = g;
age = a;
weight = w;
}
}
Would properly model your data better when you are extracting from the file (I took a guess at Person but call it what you will). We then use ArrayList like so:
public static void main (String[] args) throws IOException {
ArrayList<Person> people = new ArrayList<Person>();
Scanner file = new Scanner (new File("data.txt"));
while (file.hasNextLine()) {
String str = file.nextLine();
String[] tokens= str.split(",");
people.add(new Person(tokens[0], tokens[1], tokens[2],
Integer.parseInt(tokens[3], Double.parseDouble(tokens[4]))));
}
file.close();
Person[] arrayPeople = people.toArray();
}
ArrayLists are far more powerful than arrays as you can perform all sorts of operations on them like sorts and searches and of course you don't have to worry about their initial size because they just grow as you add new elements.

Maroun is right, you really need to use some Collections to help you with that :
public static void main(String[] args) throws Exception {
List<String[]> lines = readFiles(new File("data.txt"));
String[][] data = lines.toArray(new String[0][]);
}
public static List<String[]> readFiles(File file) {
List<String[]> data = new LinkedList<>();
Scanner scanner = null;
try {
scanner = new Scanner(file);
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
String[] tokens = line.split(",");
data.add(tokens);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
scanner.close();
}
return data;
}
Note that you can use some third party libraries like Commons IO to read the file's lines :
List<String> lines = org.apache.commons.io.FileUtils.readLines(new File("data.txt"));)
Less code = less bugs!
Hope it helps

Move this line
Object[][] data = new Object[rows][5];
below
System.out.print(rows);
But as per answers above, we suggest change the code to use array lists if possible.

Read from a file in Java

Does anybody know how to properly read from a file an input that looks like this:
0.12,4.56 2,5 0,0.234
I want to read into 2 arrays in Java like this:
a[0]=0.12
a[1]=2
a[2]=0;
b[0]=4.56
b[1]=5
b[2]=0.234
I tried using scanner and it works for input like 0 4 5 3.45 6.7898 etc but I want it for the input at the top with the commas.
This is the code I tried:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class IFFTI {
public static int size=0;
public static double[] IFFTInputREAL= new double[100];
public static double[] IFFTInputIMAG= new double[100];
static int real=0;
static int k=0;
public static void printarrays(){
for(int k=0;k<size;k++){
System.out.print(IFFTInputREAL[k]);
System.out.print(",");
System.out.print(IFFTInputIMAG[k]);
System.out.print("\n");
}
}
public static void readIFFT(String fileName){
try {
Scanner IFFTI = new Scanner(new File(fileName));
while (IFFTI.hasNextDouble()) {
if(real%2==0){
IFFTInputREAL[k] = IFFTI.nextDouble();
real++;
}
else{
IFFTInputIMAG[k] = IFFTI.nextDouble();
real++;
k++;}
}
try{
size=k;
}catch(NegativeArraySizeException e){}
} catch (FileNotFoundException e) {
System.out.println("Unable to read file");
}
}
}

I think this will do what you want:
String source = "0.12,4.56 2,5 0,0.234";
List<Double> a = new ArrayList<Double>();
List<Double> b = new ArrayList<Double>();
Scanner parser = new Scanner( source ).useDelimiter( Pattern.compile("[ ,]") );
while ( parser.hasNext() ) {
List use = a.size() <= b.size() ? a : b;
use.add( parser.nextDouble() );
}
System.out.println("A: "+ a);
System.out.println("B: "+ b);
That outputs this for me:
A: [0.12, 2.0, 0.0]
B: [4.56, 5.0, 0.234]
You'll obviously want to use a File as a source. You can use a.toArray() if you want to get it into a double[].

You will have to read the complete line.
String line = "0.12,4.56 2,5 0,0.234"; //line variable will recieve the line read
Then.. you split the line on the commas or the spaces
String[] values = line.split(" |,");
This will result in an array like this: [0.12, 4.56, 2, 5, 0, 0.234]
Now, just reorganize the contents between the two order arrays.

Reading from a file in Java is easy:
http://www.exampledepot.com/taxonomy/term/164
Figuring out what to do with the values once you have them in memory is something that you need to figure out.
You can read it one line at a time and turn it into separate values using the java.lang.String split() function. Just give it ",|\\s+" as the delimiter and off you go:
public class SplitTest {
public static void main(String[] args) {
String raw = "0.12,4.56 2,5 0,0.234";
String [] tokens = raw.split(",|\\s+");
for (String token : tokens) {
System.out.println(token);
}
}
}

EDIT Oops, this is not what you want. I don't see the logic in the way of constructing the arrays you want.
Read the content from the file
Split the string on spaces. Create for each element of the splitted array an array.
String input = "0.12,4.56 2,5 0,0.234";
String parts[] = input.split(" ");
double[][] data = new double[parts.length][];
Split each string on commas.
Parse to a double.
for (int i = 0; i < parts.length; ++i)
{
String part = parts[i];
String doubles[] = part.split(",");
data[i] = new double[doubles.length];
for (int j = 0; j < doubles.length; ++j)
{
data[i][j] = Double.parseDouble(doubles[j]);
}
}

File file = new File("numbers.txt");
BufferedReader reader = null;
double[] a = new double[3];
double[] b = new double[3];
try {
reader = new BufferedReader(new FileReader(file));
String text = null;
if ((text = reader.readLine()) != null) {
String [] nos = text.split("[ ,]");
for(int i=0;i<nos.length/2;i++){
a[i]=Double.valueOf(nos[2*i]).doubleValue();
b[i]=Double.valueOf(nos[2*i+1]).doubleValue();
}
}
for(int i=0;i<3;i++){
System.out.println(a[i]);
System.out.println(b[i]);
}
} catch (FileNotFoundException e) {
} catch (IOException e) {
} finally {
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
}
}