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Write Data to a CSV File in Java
How to read/A library named OpenCSV provides API’s to read and write data from/into a.CSV file. Here it is explained how to read the contents of a .csv file using a Java program.
Maven dependency
<dependency> <groupId>com.opencsv</groupId> <artifactId>opencsv</artifactId> <version>4.4</version> </dependency> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.9</version> </dependency>
The CSVReader class of the com.opencsv package represents a simple csv reader. While instantiating this class you need to pass a Reader object representing the file to be read as a parameter to its constructor. It provides methods named readAll() and readNext() to read the contents of a .csv file
Using the readNext() method
The readNext() method of the CSVReader class reads the next line of the .csv file and returns it in the form of a String array.
Example
The following Java program demonstrates how to read the contents of a .csv file using the readNext() method.
import java.io.FileReader; import com.opencsv.CSVReader; public class ReadFromCSV { public static void main(String args[]) throws Exception { //Instantiating the CSVReader class CSVReader reader = new CSVReader(new FileReader("D://sample.csv")); //Reading the contents of the csv file StringBuffer buffer = new StringBuffer(); String line[]; while ((line = reader.readNext()) != null) { for(int i = 0; i<line.length; i++) { System.out.print(line[i]+" "); } System.out.println(" "); } } }
Output
id name salary start_date dept 1 Rick 623.3 2012-01-01 IT 2 Dan 515.2 2013-09-23 Operations 3 Michelle 611 2014-11-15 IT 4 Ryan 729 2014-05-11 HR 5 Gary 843.25 2015-03-27 Finance 6 Nina 578 2013-05-21 IT 7 Simon 632.8 2013-07-30 Operations 8 Guru 722.5 2014-06-17 Finance
Writing data to a CSV file
The CSVWriter class of the com.opencsv package represents a simple csv writer. While instantiating this class you need to pass a Writer object representing the file, to which you want to write the data, as a parameter to its constructor. It provides methods named writeAll() and writeNext() to write data to a .csv file
Using the writeNext() method −
The writeNext() method of the CSVWriter class writes the next line to the .csv file
Example
The following Java program demonstrates how to write data to a .csv file using the writeNext() method.
import java.io.FileWriter; import com.opencsv.CSVWriter; public class WritingToCSV { public static void main(String args[]) throws Exception { //Instantiating the CSVWriter class CSVWriter writer = new CSVWriter(new FileWriter("D://output.csv")); //Writing data to a csv file String line1[] = {"id", "name", "salary", "start_date", "dept"}; String line2[] = {"1", "Krishna", "2548", "2012-01-01", "IT"}; String line3[] = {"2", "Vishnu", "4522", "2013-02-26", "Operations"}; String line4[] = {"3", "Raja", "3021", "2016-10-10", "HR"}; String line5[] = {"4", "Raghav", "6988", "2012-01-01", "IT"}; //Writing data to the csv file writer.writeNext(line1); writer.writeNext(line2); writer.writeNext(line3); writer.writeNext(line4); //Flushing data from writer to file writer.flush(); System.out.println("Data entered"); } }
Output
Data entered