CODEWITHSUNDEEP
java
user2738145
user2738145

Reputation: 116

having an error reading from a file in java

need help fixing this error. I am trying to print out the array length of string countryNames. 

Exception in thread "main" java.util.NoSuchElementException: No line found
at java.util.Scanner.nextLine(Scanner.java:1516)
at CSVReader.setUp(CSVReader.java:25)
at CSVReader.<init>(CSVReader.java:16)
at TestCSVReader.main(TestCSVReader.java:16)

I am reading from a cvs file and i keep getting the error above. Below is my code:

import java.io.*;
import java.util.Scanner;
public class CSVReader {
//String countryNames;
String[] countryNames;
int yearLabels;
int[] yearNum;
 double cellularDataTable;
 double[][] tables;
Scanner scan;

public CSVReader(String filename)// throws FileNotFoundException 
{ 
    setUp(filename);
}
private void setUp(String filename) //throws FileNotFoundException
{
    File file = new File(filename);
    try{
        String input="";
        scan = new Scanner(file);
        scan.nextLine();
        while((input=scan.nextLine())!=null)
        {
            String[] countryNames = input.split(",");
            //int a = Integer.parseInt(countryNames[1]);
            System.out.println(countryNames[0]);
            //System.out.println(a);
        }
        scan.close();
    }
    catch(FileNotFoundException e)
    {
        System.out.println(e);
    }
}
    public String[] getCountryNames()
{
    return countryNames;
}

Below is my TestCSV class file:

public class TestCSVReader {

/**
 * Includes test examples for class CSVReader.
 */
public static void main(String[] args) 
{   
    final String FILENAME = "data/cellular.csv";    // Directory path for Mac OS X
    //final String FILENAME = "data\cellular.csv";  // Directory path for Windows OS (i.e. Operating System)


    CSVReader parser = new CSVReader(FILENAME);

    String [] countryNames = parser.getCountryNames();
    System.out.println(countryNames.length);
    }

my csv file looks like this below: This is a summary as i did not want to print out the entire 252 countries. Basically i take in 252 countries and store it in a string array, the years and store them in an int array and stats of cellular data of each country in a 2d double array. I am new to programming and would like to know if i am heading in the right direction and if not how would you country name in a string array, the years in an int. and stats in a 2d double array.

cvs file looks like this:

World Development Indicators
Number of countries,252
Country  Name,1960,1961,1962,1963,1964,1965,1966,1967,1968,1969,1970,1971,1972,1973,1974,1975,1976,1977,1978,1979,1980,1981,1982,1983,1984,1985,1986,1987,1988,1989,1990,1991,1992,1993,1994,1995,1996,1997,1998,1999,2000,2001,2002,2003,2004,2005,2006,2007,2008,2009,2010,2011,2012
 Aruba,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0.029310471,0,0,2.138784453,3.605985937,3.98141538,6.16435217,13.48254011,16.50927821,57.05427692,65.05605558,72.10431377,99.64250268,103.3849507,108.1325002,112.2180618,119.2038996,126.2103374,129.72824,0,131.8565401
Andorra,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1.307211734,1.278625641,1.250259142,4.424155104,8.538444783,13.44671556,22.12730607,32.14530928,35.99902139,43.27794118,45.77115817,68.60251444,73.82494308,79.48487497,84.27763597,78.1171579,80.2836099,82.06181111,84.06818386,83.53432222,81.50204186
 Afghanistan,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0.112598381,0.865196277,2.498055472,4.826865367,9.833164022,17.71624331,29.22037376,37.89493697,45.77817474,60.32631999,60.35299258

Upvotes: 3

Views: 1707

Answers (4)

A-Tomy-k
A-Tomy-k

Reputation: 91

The problem posed in the thread has been solved with 

while(scan.hasNextLine()) {

But there's another problem that you'll find in your code. Inside the loop, you've created a local variable countryNames[], which isn't related with the String[] countryNames declared in the class.

I recommend you to change the declaration just like that:

public class CSVReader {     
    List<String> countryNames;

And initialize it in the constructor of the class:

public CSVReader(String filename)// throws FileNotFoundException 
{ 
    countryNames = new ArrayList<String>();
    setUp(filename);   
}

ArrayList allows you to add values dynamically. So, inside the loop, you must add each country name to this ArrayList:

String[] countryValues = input.split(",");
countryNames.add(countryValues[0]);

Upvotes: 4

Tom
Tom

Reputation: 17567

This line while((input=scan.nextLine())!=null) tries to read separate lines from the file until input becomes null. But nextLine() will throw an exception if there are no more lines available.

To avoid this, change your code to the following

//String input=""; // this line is obsolete
scan = new Scanner(file);
scan.nextLine();
while(scan.hasNextLine()) {
    final String input = scan.nextLine(); // read the line after the check (to make sure there is a line available)
    String[] countryNames = input.split(",");
    //int a = Integer.parseInt(countryNames[1]);
    System.out.println(countryNames[0]);
    //System.out.println(a);
}

Upvotes: 6

ToYonos
ToYonos

Reputation: 16833

Maybe like this, you have a specific method to test if scan has more element to read

String input="";
scan = new Scanner(file);
scan.nextLine();
while(scan.hasNext())
{
    input=scan.nextLine();
    String[] countryNames = input.split(",");
    //int a = Integer.parseInt(countryNames[1]);
    System.out.println(countryNames[0]);
    //System.out.println(a);
}
scan.close();

Upvotes: 2

babeyh
babeyh

Reputation: 699

I think countryNames array is null. try to initialize it before adding data. debug your code and check countryNames...

String[] countryNames = new String[...]

if you don't know length of array, you had better use Arraylist. (when using Arraylist,you don't have to initialize first.)

Upvotes: 0

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