The CSV stands for Comma-Separated Values. It is a simple file format which is used to store tabular data in simple text form, such as a spreadsheet or database.
The files in the CSV format can be imported to and exported from programs (Microsoft Office and Excel) which store data in tables. The CSV file used a delimiter to identify and separate different data token in a file.
The CSV file format is used when we move tabular data between programs that natively operate on incompatible formats. There are following ways to read CSV file in Java. The default separator of a CSV file is a comma (,).
Read CSV file using Apache Commons CSV
Here in this example we will read csv file in java by using the Apache Commons CSV library.
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.techblogstation</groupId>
<artifactId>ReadCSVFiles</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-csv -->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-csv</artifactId>
<version>1.7</version>
</dependency>
</dependencies>
</project>Reading a CSV file records by column index:
Sample CSV File
Name,Phone,Country
Rahul,986525689,India
Sam,852647182,GermanyWe have created a BufferedReader for the file and passed it to CSVParser with the default CSV format. And once we get the CSVParser then we can iterate over records one by one using a for loop.
Program for this is:
package com.techblogstation.csv;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVRecord;
import java.io.IOException;
import java.io.Reader;
import java.nio.file.Files;
import java.nio.file.Paths;
public class ReadCSVFile
{
private static final String FILE_PATH = "E:\\Files\\Employees.csv";
public static void main(String[] args) throws IOException
{
// using try with resources
try (
Reader reader = Files.newBufferedReader(Paths.get(FILE_PATH));
CSVParser csvParser = new CSVParser(reader, CSVFormat.DEFAULT);
) {
for (CSVRecord csvRecord : csvParser) {
// Getting values by Column Index
String name = csvRecord.get(0);
String phone = csvRecord.get(1);
String country = csvRecord.get(2);
System.out.println("Record Number - " + csvRecord.getRecordNumber());
System.out.println("Name : " + name);
System.out.println("Phone : " + phone);
System.out.println("Country : " + country);
System.out.println("\n");
}
}
}
}##Output##
Record Number - 1
Name : Rahul
Phone : 986525689
Country : India
Record Number - 2
Name : Sam
Phone : 852647182
Country : Germany
Reading a CSV file records by column name:
The ignoreHeaderCase is used to not make the header names case-sensitive and the trim method is used to trim leading and trailing blank spaces from the values.
package com.techblogstation.csv;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVRecord;
import java.io.IOException;
import java.io.Reader;
import java.nio.file.Files;
import java.nio.file.Paths;
public class ReadCSVFile
{
private static final String FILE_PATH = "E:\\Files\\Employees.csv";
public static void main(String[] args) throws IOException
{
// using try with resources
try (
Reader reader = Files.newBufferedReader(Paths.get(FILE_PATH));
CSVParser csvParser = new CSVParser(reader, CSVFormat.DEFAULT
.withHeader("Name","Phone","Country")
.withIgnoreHeaderCase()
.withTrim().withSkipHeaderRecord());
) {
for (CSVRecord csvRecord : csvParser) {
// Getting values by Name of each column
String name = csvRecord.get("Name");
String phone = csvRecord.get("Phone");
String country = csvRecord.get("Country");
System.out.println("Record Number - " + csvRecord.getRecordNumber());
System.out.println("Name : " + name);
System.out.println("Phone : " + phone);
System.out.println("Country : " + country);
System.out.println("\n");
}
}
}
}##Output##
Record Number - 1
Name : Rahul
Phone : 986525689
Country : India
Record Number - 2
Name : Sam
Phone : 852647182
Country : Germany
Read CSV file using OpenCSV
Here in this example we will read csv file in java by using the OpenCSV library
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.techblogstation</groupId>
<artifactId>ReadCSVFiles</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<!-- https://mvnrepository.com/artifact/com.opencsv/opencsv -->
<dependency>
<groupId>com.opencsv</groupId>
<artifactId>opencsv</artifactId>
<version>5.0</version>
</dependency>
</dependencies>
</project>Read Records one by one
package com.techblogstation.csv;
import com.opencsv.CSVReader;
import com.opencsv.exceptions.CsvValidationException;
import java.io.IOException;
import java.io.Reader;
import java.nio.file.Files;
import java.nio.file.Paths;
public class ReadCSVFile
{
private static final String FILE_PATH = "E:\\Ashish\\Files\\Employees.csv";
public static void main(String[] args) throws IOException, CsvValidationException
{
// using try with resources
try (
Reader reader = Files.newBufferedReader(Paths.get(FILE_PATH));
CSVReader csvReader = new CSVReader(reader);
) {
// Fetching Records One by One in a String array
String[] csvRecord;
while ((csvRecord = csvReader.readNext()) != null)
{
System.out.println("Name : " + csvRecord[0]);
System.out.println("Phone : " + csvRecord[1]);
System.out.println("Country : " + csvRecord[2]);
}
}
}
}Conclusion
Readers you have learned how to read a csv file in java using apache commons csv and open csv api.
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