How to select few columns from one csv and write it into another csv using java

Question

I am writing an program to select few columns from one csv and write it into another csv. i am able to select the columns i want to write but i am not able to write it into another csv.

public class ReadingCSV {

public static void main(String[] args) {

    String csvFile = "/Users/Desktop/NEW Automation/combined.csv";
    String out = "/Users/Desktop/NEW Automation/a.csv";
    BufferedReader br = null;
    String line = "";
    String cvsSplitBy = ",";

    try {

        br = new BufferedReader(new FileReader(csvFile));
        while ((line = br.readLine()) != null) {

            // use comma as separator
            String[] mydata = line.split(cvsSplitBy);
            //System.out.println("[Client = " + mydata[1] + " , Acct_id=" + mydata[2] + "]");
            PrintWriter output = new PrintWriter("out", "UTF-8");

            output.println(mydata[0] + cvsSplitBy + mydata[1] + cvsSplitBy + mydata[2]);
        }

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (br != null) {
            try {
                br.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

}

}

Atul · Accepted Answer · 2017-02-19 21:59:07Z

1

You have to initialize Printwriter outside your while block, and you need to close it in finally.

public static void main(String[] args) {

String csvFile = "/Users/Desktop/NEW Automation/combined.csv";
String out = "/Users/Desktop/NEW Automation/a.csv";
BufferedReader br = null;
String line = "";
String cvsSplitBy = ",";
PrintWriter output = new PrintWriter("out", "UTF-8");
try {


    br = new BufferedReader(new FileReader(csvFile));
    while ((line = br.readLine()) != null) {

        // use comma as separator
        String[] mydata = line.split(cvsSplitBy);
        //System.out.println("[Client = " + mydata[1] + " , Acct_id=" + mydata[2] + "]");

        output.println(mydata[0] + cvsSplitBy + mydata[1] + cvsSplitBy + mydata[2]);
    }

} catch (FileNotFoundException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
} finally {
    if (br != null) {
        try {
            br.close();
            output.close(); 
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

I will also suggest to use opensource project http://opencsv.sourceforge.net/ to parse csv instead of writing your own code.

edited Feb 19, 2017 at 21:59

answered Feb 18, 2017 at 7:23

Atul

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2 Comments

BATMAN_2008 Over a year ago

Thanks for the response. But its throwing error in finally block for the output.close(); as output is an unresolved variable. I commented it out and ran the program, its not populating anything in my output csv.

Atul Over a year ago

@Aravinda I just updated the code and moved output outside try block.

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