How to extract CSV columns with the specific header names and output to a new file using JAVA and Op-CodePudding

If I have the file. The content inside looks like this:

ID,Name,Gender,Age,Enabled
1,Kevin,M,1,true
2,James,M,2,true
3,Jane,F,3,true
4,Jenny,F,4,true

Now I would like to extract the columns: ID, name, Gender and output them to a new file the following:

ID,Name,Age
1,Kevin,1
2,James,2
3,Jane,3
4,Jenny,4

I would like to extract the columns based on the header name, instead of the index number.

I would like to use OpenCSV.

How to achieve it?

CodePudding user response：

There is no in-built method in CSVReader to read values using column names. But you can have a workaround as below for that by have another method created to get the correct column position.

    private int getPositionUsingName(String[] allColumnNames, String columnName) {
           return Arrays.asList(allColumnNames).indexOf(columnName);
    }

So your method will be like:

CSVReader csvReader = new CSVReader(new FileReader("inputFile.csv"));
String [] allColumnNames;
String [] nextLine;
int idPosition;
int namePosition;
int agePosition;

allColumnNames = csvReader.readNext();
idPosition = getPositionUsingName(allColumnNames, "ID");
namePosition = getPositionUsingName(allColumnNames, "Name");
agePosition = getPositionUsingName(allColumnNames, "Age");

while ((nextLine = csvReader.readNext()) != null) {
   System.out.println(nextLine[idPosition] " " nextLine[namePosition] " " nextLine[agePosition]);
}