https://www.callicoder.com/java-read-write-csv-file-apache-commons-csv/
Reading a CSV file (Access Values by Names assigned to each column)
In the earlier example, We accessed the values in each record using their column index. If you don’t want to use column indexes to retrieve the values in each record, then you can assign names to each column in the CSV file and retrieve the values using the assigned names.
Check out the following example where we define a manual header and retrieve the values using the header names.
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVRecord;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.nio.file.Files;
import java.nio.file.Paths;
public class CSVReaderWithManualHeader {
private static final String SAMPLE_CSV_FILE_PATH = "./users.csv";
public static void main(String[] args) throws IOException {
try (
Reader reader = Files.newBufferedReader(Paths.get(SAMPLE_CSV_FILE_PATH));
CSVParser csvParser = new CSVParser(reader, CSVFormat.DEFAULT
.withHeader("Name", "Email", "Phone", "Country")
.withIgnoreHeaderCase()
.withTrim());
) {
for (CSVRecord csvRecord : csvParser) {
// Accessing values by the names assigned to each column
String name = csvRecord.get("Name");
String email = csvRecord.get("Email");
String phone = csvRecord.get("Phone");
String country = csvRecord.get("Country");
System.out.println("Record No - " + csvRecord.getRecordNumber());
System.out.println("---------------");
System.out.println("Name : " + name);
System.out.println("Email : " + email);
System.out.println("Phone : " + phone);
System.out.println("Country : " + country);
System.out.println("---------------\n\n");
}
}
}
}
Generating a CSV file
Finally, Let’s see an example of generating a CSV file with Apache Commons CSV.
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVPrinter;
import java.io.*;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
public class CSVWriter {
private static final String SAMPLE_CSV_FILE = "./sample.csv";
public static void main(String[] args) throws IOException {
try (
BufferedWriter writer = Files.newBufferedWriter(Paths.get(SAMPLE_CSV_FILE));
CSVPrinter csvPrinter = new CSVPrinter(writer, CSVFormat.DEFAULT
.withHeader("ID", "Name", "Designation", "Company"));
) {
csvPrinter.printRecord("1", "Sundar Pichai ♥", "CEO", "Google");
csvPrinter.printRecord("2", "Satya Nadella", "CEO", "Microsoft");
csvPrinter.printRecord("3", "Tim cook", "CEO", "Apple");
csvPrinter.printRecord(Arrays.asList("4", "Mark Zuckerberg", "CEO", "Facebook"));
csvPrinter.flush();
}
}
}
The above program will generate the following CSV file -
ID,Name,Designation,Company
1,Sundar Pichai ♥,CEO,Google
2,Satya Nadella,CEO,Microsoft
3,Tim cook,CEO,Apple
4,Mark Zuckerberg,CEO,Facebook
