Error reading from file in java
need help fixing this error. I am trying to print the length of a countryNames string array.
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 cvs file and I keep getting above error. 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: This is a summary as I didn't want to print all 252 countries. Basically I take in 252 countries and store them in an array of strings, years and store them in an array of int and each country's cell statistics in a two dimensional 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 name the country in an array of strings, years in int. and statistics in a two-inch array.
The 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
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This line while((input=scan.nextLine())!=null)
tries to read individual lines from the file until input
it becomes null
. But it nextLine()
will throw an exception if there are no more rows 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);
}
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The problem posed in the thread was solved with
while(scan.hasNextLine()) {
But there is also another problem you will find in your code. Within the loop, you have created a local variable countryNames [] that is not associated with the String [] countryNames declared in the class.
I recommend that you change your declaration like this:
public class CSVReader {
List<String> countryNames;
And initialize it in the class constructor:
public CSVReader(String filename)// throws FileNotFoundException
{
countryNames = new ArrayList<String>();
setUp(filename);
}
ArrayList allows you to dynamically add values. So, inside the loop, you have to add the name of each country to this ArrayList:
String[] countryValues = input.split(",");
countryNames.add(countryValues[0]);
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Perhaps so, you have a special method of checking if there is more item to read in the scan
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();
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I think the countryNames array is null. try initializing it before adding data. debug your code and check country names ...
String[] countryNames = new String[...]
If you don't know the length of the array, you are better off using Arraylist. (when using Arraylist, you don't need to initialize first.)
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