Why do I get IndexOutOfBounds in my function?

Question

I am reading a csv file and then writing it to other file with additional column, when I am moving the data from a list to the additional column I got IndexOutOfBounds

private void writeDataToCSVDestinationFile(Path csvPath, Path destPath, String colToNormalize) throws IOException, CsvException {
        CSVWriter writer = new CSVWriter(new FileWriter(destPath.toString()));
        CSVReader reader = new CSVReader(new FileReader(csvPath.toString()));
        
        String [] headerDes = new String [header.length+1];  
        for (int i=0; i<header.length; i++){
        headerDes[i]= header[i];
        }
        headerDes[header.length]= colToNormalize+"_scaled";
        writer.writeNext(headerDes);
        
       String[] eachLineInTheOriginalFile;
       String[] lineToBeWritten = new String[headerDes.length];
         int j =0;
       while ((eachLineInTheOriginalFile=reader.readNext())!=null){
             
            for (int i =0; i<eachLineInTheOriginalFile.length; i++ ){
            lineToBeWritten[i] = eachLineInTheOriginalFile[i];
            }
            lineToBeWritten[eachLineInTheOriginalFile.length]=dataAfterNormalization.get(j).toString(); //the line  generate the exception
            j++;
        }
       writer.writeNext(lineToBeWritten);
    }

Any one can help me to solve it.

You set as `String[] lineToBeWritten = new String[headerDes.length];` why would you expect `lineToBeWritten[eachLineInTheOriginalFile.length]` to be relevant? — Scary Wombat, Jul 08 '21 at 01:24

score 0 · Answer 1 · answered Jul 08 '21 at 01:31

0

There is no index j in dataAfterNormalization, so your get is throwing that error.

You also have another problem on that line. The final index of lineToBeWritten is eachLineInTheOriginalFile.length - 1

answered Jul 08 '21 at 01:31

James Schultz

171
6

What do you mean no index `j`. It starts at `0` and continues incrementing. – WJS Jul 08 '21 at 01:40
Correct, `j` contains a value. At some point in the loop, the dataAfterNormalization object does not have anything at index `j`. When get(j) is called on it it throws an exception. – James Schultz Jul 08 '21 at 01:50
@ James Schultz How can I solve it please – shahed aa Jul 08 '21 at 01:54
I can't tell from your snippet, is start by looking at where dataAfterNormalization comes from. Check `dataAfterNormalization.size()` and make sure it is >= `eachLineInTheOriginalFile.length`. – James Schultz Jul 08 '21 at 02:00

score 0 · Answer 2 · answered Jul 12 '21 at 03:05

0

The reason the reported error might be, the number of elements in the list "dataAfterNormalization" are less than the number of rows(lines of data) in the soure csv (eachLineInTheOriginalFile)

answered Jul 12 '21 at 03:05

Giri

14
1

score -1 · Answer 3 · answered Jul 12 '21 at 02:10

This code may work for you 

package index;

import  java.util.List;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;

import com.opencsv.CSVReader;
import com.opencsv.CSVWriter;
import com.opencsv.exceptions.CsvException;

public class Sample {

    public static void main(String[] args) {
        List<String> dataAfterNormalization=new ArrayList<String>();  
        dataAfterNormalization.add("Development");
        dataAfterNormalization.add("QA");
        
        try{
        Path csvPath = Paths.get("C:\\YourFolderName\\source.csv");
        Path destPath = Paths.get("C:\\YourFolderName\\destination.csv");
        writeDataToCSVDestinationFile(csvPath,destPath,"Department", dataAfterNormalization);
        }catch (Exception e) {
            e.printStackTrace();
        }
                    
    }
    
private static void writeDataToCSVDestinationFile(Path csvPath, Path destPath, String colToNormalize, List<String> dataAfterNormalization) throws IOException, CsvException {
    CSVWriter writer = new CSVWriter(new FileWriter(destPath.toString()));
    CSVReader reader = new CSVReader(new FileReader(csvPath.toString()));
    
    String[] header = reader.readNext(); // assuming first read
    String [] headerDes = new String [header.length+1];  
    for (int i=0; i<header.length; i++){
    headerDes[i]= header[i];

    }
    headerDes[header.length]= colToNormalize+"_scaled";
    writer.writeNext(headerDes);

   String[] eachLineInTheOriginalFile;
   String[] lineToBeWritten = new String[headerDes.length];
     int j =0;
   while ((eachLineInTheOriginalFile=reader.readNext())!=null){
         
        for (int i =0; i<eachLineInTheOriginalFile.length; i++ ){
        lineToBeWritten[i] = eachLineInTheOriginalFile[i];
        }
        lineToBeWritten[eachLineInTheOriginalFile.length]=dataAfterNormalization.get(j).toString();
        j++;
        writer.writeNext(lineToBeWritten);
    }
   writer.close();
   reader.close();
} 

}

Why do I get IndexOutOfBounds in my function?

3 Answers3