How to use the OpenCSV library in Java for read and write operations of CSV files
In Java, you can use the OpenCSV library to perform the read and write operation of the CSV file.CSV (comma division value) is a commonly used file format for storing structured data.
First, you need to add the dependencies of the OpenCSV library to the project.You can configure the following dependencies in Maven or Gradle:
// Maven
<dependency>
<groupId>com.opencsv</groupId>
<artifactId>opencsv</artifactId>
<version>5.3</version>
</dependency>
// Gradle
implementation 'com.opencsv:opencsv:5.3'
Then, you can use the following steps to use OpenCSV to read and write the CSV file:
1. Import the necessary classes and packages:
import com.opencsv.CSVReader;
import com.opencsv.CSVWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
2. Read the CSV file:
try (CSVReader reader = new CSVReader(new FileReader("input.csv"))) {
String[] line;
while ((line = reader.readNext()) != null) {
// Read each line of data and process it
for (String data : line) {
System.out.print(data + " ");
}
System.out.println();
}
} catch (IOException e) {
e.printStackTrace();
}
In the above code, first create a CSVReader object and pass the CSV file to it.Then use the `Readnext ()" method to read the content of the CSV file one by one, and store each line of data in a string array.
3. Write into CSV file:
try (CSVWriter writer = new CSVWriter(new FileWriter("output.csv"))) {
String[] header = {"Name", "Age", "City"};
writer.writeNext(header);
String[] row1 = {"John Doe", "25", "New York"};
String[] row2 = {"Jane Smith", "30", "San Francisco"};
writer.writeNext(row1);
writer.writeNext(row2);
System.out.println("CSV file written successfully.");
} catch (IOException e) {
e.printStackTrace();
}
In the above code, first create a CSVWriter object and specify the CSV file to be written.Then, you can write data through the method of `` writenext () `.You can use a string array to represent the data of each line.
In addition, you can also use other methods provided by the OpenCSV library to perform more complicated operations, such as reading specific columns of data and CSV files with specific separators.
In summary, using the OpenCSV library can easily perform read and write operations of CSV files in Java.Make sure the required dependencies are added to the project, and read and write the CSV files with appropriate methods.
