CODEWITHSUNDEEP
javacsvfile-io
Reece Akhtar
Reece Akhtar

Reputation: 45

Problems reading a CSV file in Java. Only the first line is read

For a Java homework assignment, I need to create a class that reads and writes CSV files. I'm currently having some problems reading the the CSV. The code below, only outputs the first line of the code and then generates the following error message: 'Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1 at com.gc01.FileManager.CSVManager.main(CSVManager.java:27)".

I have looked at various examples, and I am aware of the 'opencsv' package, but I need to write this code myself. I have located the problem to the statement "System.out.print(data[i]);". However, when cross-referencing this code it all seems to be fine.

I am using the methods from the FileInput class, as specified by my teacher (http://www.devjavasoft.org/SecondEdition/SourceCode/Share/FileInput.java).

public class CSVManager {
    public static void main(String [] args){

        Scanner sc = new Scanner (System.in);
        System.out.println("Please enter the file directory of the chosen CSV");
        System.out.println("For Example: /Users/UserName/Downloads/FileName.csv");
        ///Users/ReeceAkhtar/Desktop/GeoIPCountryWhois.csv
        final String fileName = sc.nextLine();
        System.out.println("How many columns?");
        final int columns = sc.nextInt();

        BufferedReader br = null;
        String line = "";
        String splitBy = " , ";

        try {
            br = new BufferedReader(new FileReader(fileName));
            while((line = br.readLine()) != null) {
                for (int i = 0; i < columns; i++) {
                    String[] data = line.split(splitBy);
                    System.out.print(data[i]);
                }
            }
        } catch (FileNotFoundException e){
            e.printStackTrace();
        } catch (IOException e) {   
            e.printStackTrace();  
        } finally {  
            if (br != null) {  
            try {  
                    br.close();  
                } catch (IOException e) {  
                    e.printStackTrace();  
                }
            }
        }
        System.out.println("File Read");
    }
}

Upvotes: 0

Views: 2587

Answers (3)

Sage
Sage

Reputation: 15418

 while((line = br.readLine()) != null){
    for (int i = 0; i < columns; i++){
    String[] data = line.split(splitBy);
    System.out.print(data[i]);
    }
  1. You are splitting one line multiple times inside the for loop without any reason.
  2. You are using " , " for splitting (which might be the reason you are having ArrayIndexOfBound exception) Instead use ","; use trim() on data[i] to get rid of trailing/leading white space if you wish to.
  3. After Splitting, put checking whither data.length is equal to columns for consistency.
  4. We are now in the era of JDK 7 where we can use try-with-resource which close the declared resource inside try(){} context, allowing us to get rid of finally block

So your could should look like as follows:

  try (BufferedReader br = new BufferedReader(new FileReader(fileName))){
     while((line = br.readLine()) != null){
        String[] data = line.split(splitBy);

        if(data.length != columns)continue; // check for consistency, 
                                       //might throw an exception 

        for (int i = 0; i < columns; i++){
          System.out.print(data[i].trim());
        }

  }catch(IoExection ex)
  {
     ex.printStackTrace();  
  }

Upvotes: 0

yilmazburk
yilmazburk

Reputation: 917

Try this one. If you take splitting out the for loop everything will be okay.

String[] data = line.split(splitBy);
while((line = br.readLine()) != null){
    for (int i = 0; i < columns; i++){
        System.out.print(data[i]);
    }
}

Upvotes: 1

sanbhat
sanbhat

Reputation: 17622

Exception is very clear

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1

means, you are trying to access 1st element in the array which doesn't exist

Since you are saying System.out.print(data[i]); is the line where the exception is occurring, then for the first line data must have populated with only single element

Debug the issue with IDE to find out why split method is resulting unexpected elements. I suspect usage of spaces around , is the cause in " , "

Upvotes: 1

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