Camel: How to use the CSV framework in the Java library
How to use the CSV framework in the Java class library
CSV (comma separation value) is a commonly used text format that is used to store table data as pure text files.In Java, we can use the CSV framework to read and write into the CSV file.This article will introduce how to use the CSV framework in the Java library and provide the corresponding Java code example.
First, we need to introduce the dependency library of the CSV framework.In this example, we will use one of the most popular CSV frameworks in the Java class library, the Apache Commons CSV.You can import this framework by adding the following dependencies to your Maven configuration file:
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-csv</artifactId>
<version>1.8</version>
</dependency>
Below is a sample CSV file (data.csv), which contains information about names and age:
Name, age
Zhang San, 20
Li Si, 25
Wang Wu, 30
Next, we will show how to use Apache Commons CSV frameworks to read and write CSV files.
1. Read the CSV file:
The following is a sample code. Demonstrate how to use the CSV framework to read the data from the CSV file and print it:
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;
public class CSVReaderExample {
public static void main(String[] args) {
try {
Reader reader = new FileReader("data.csv");
CSVParser csvParser = new CSVParser(reader, CSVFormat.DEFAULT
.withheader ("Name", "Age")
.withIgnoreHeaderCase()
.withTrim());
for (CSVRecord csvRecord : csvParser) {
String name = csvrecord.get ("name");
int Age = Integer.parseint (CSVRECORD.GET ("Age");
System.out.println ("Name:" + Name);
System.out.println ("age:" + Age);
System.out.println("---------------------------");
}
csvParser.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
The above code first creates a Filereader object to read the CSV file, and then use the CSVFormat class to define the CSV format and set the name of the title line.Then, we obtained the values of each column by traversing the CSVRecord object and printed.
2. Write into CSV file:
The following is a sample code, demonstrating how to use the CSV framework to write the data to the CSV file:
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVPrinter;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.Arrays;
import java.util.List;
public class CSVWriterExample {
public static void main(String[] args) {
try {
Writer writer = new BufferedWriter(new FileWriter("output.csv"));
CSVPrinter csvPrinter = new CSVPrinter(writer, CSVFormat.DEFAULT
.withheader ("Name", "Age");
List <string> Person1 = Arrays.aslist ("Zhang San", "20");
List <string> Person2 = Arrays.aslist ("Li Si", "25");
List <string> Person3 = Arrays.aslist ("Wang Wu", "30");
csvPrinter.printRecord(person1);
csvPrinter.printRecord(person2);
csvPrinter.printRecord(person3);
csvPrinter.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
In this example, we use the CSVPrinter class to use each line as a Record object, and then write the information of each person into the file with the PrintRecord () method.
Through the above example code, we can see how to use the CSV framework in the Java library to read and write the CSV file.You can modify the code based on actual needs and analyze or generate data based on the structure of the CSV file.I hope this article can help you handle CSV files in Java.
