How to add values to specific column in existing csv file using java

Question

For example header1,header2,header3 are there in csv file and how to add values to header3 column in existing csv file. Below is my code and trying to add values to column3.

BufferedReader br=null;
BufferedWriter bw=null;

try {
    File file = new File("ResponseTest.csv");
    File newfile = new File("ResponseTestNew.csv");

    br = new BufferedReader(new InputStreamReader(new FileInputStream(file))) ;  //old file includes header 1,header2
    bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(newfile))); //new file

    String line = null;
    String value3= "7898798";

    while((line = br.readLine())!=null){
        String addedValue = "\t"+"value3";  // adding value to column -header3
        bw.write(line+addedValue +System.lineSeparator());
    }
} catch(Exception e){
    System.out.println(e);
} finally  {
    br.close();
    bw.close();
}

output is :

header1|header2|header3 value3
value1|value2|value3

problem is value3 is getting added from first row of header3

Jens · Accepted Answer · 2022-07-22 08:24:13Z

0

You should ignore line one in your loop:

boolean isFirstLine = true;
while((line = br.readLine())!=null){
    if (isFirstline){
       bw.write(line+System.lineSeparator());
       isFirstline = false;
       continue;
    }
    bw.write(line+ "\t"+"value3"+System.lineSeparator());

}

answered Jul 22, 2022 at 8:24

Jens

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3 Comments

Priya Over a year ago

I can see that values are getting added from second line to last column. but its ignoring all the headers and not writing to csv file. and also the in column 3 same value is adding in all the lines. im trying to pass that dynamically. Could you please suggest. eg : header|header2|header3| value1|value2|value3 (value 3 is getting repeatedly for all lines)

Jens Over a year ago

and also the in column 3 same value is adding in all the lines that is exactly what you code shows us

Jens Over a year ago

* but its ignoring all the headers and not writing to csv file.* shouldn't. It should be written in the line bw.write(line+System.lineSeparator());

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