Genjava CSV framework development case commonly used in the Java class library
CSV framework development case commonly used in the Java class library
CSV (COMMA SEPARATED VALUE) is a common text file format that is commonly used in data introduction, export, processing and storage.In the development of Java, there are many mature CSV frameworks for use to facilitate developers to process CSV data.Next, we will introduce the usage of the CSV framework commonly used in the Java class library through an example.
Suppose we have a CSV file (Students.csv) that stores student information, including the following: student ID, name, age, and grade.We need to read this file and perform some operations, such as calculating the average score and the largest student information output.
First, we can use the Apache Commons CSV framework to read the CSV file and convert it to the Java object.The following is a code example using Apache Commons CSV framework to read CSV files:
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;
public class CSVReaderExample {
public static void main(String[] args) {
try (CSVParser parser = new CSVParser(new FileReader("students.csv"), CSVFormat.DEFAULT)) {
for (CSVRecord record : parser) {
String studentId = record.get(0);
String studentName = record.get(1);
int studentAge = Integer.parseInt(record.get(2));
double studentScore = Double.parseDouble(record.get(3));
// Do other operations, such as calculating the average score or finding the oldest student information
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above example, we use the `CSVPARSER` class to read records from the CSV file and use the` csvrecord` class to obtain the attribute value of each record.
In addition to reading CSV files, we can also use some class libraries to create, write and modify the CSV files.For example, using the OpenCSV framework can easily create and write CSV files.The following is an example of creating a CSV file using OpenCSV framework:
import com.opencsv.CSVWriter;
import java.io.FileWriter;
import java.io.IOException;
public class CSVWriterExample {
public static void main(String[] args) {
try (CSVWriter writer = new CSVWriter(new FileWriter("students.csv"))) {
String [] header = {"student ID", "name", "age", "grade"};
writer.writeNext(header);
// Write student information into CSV files
String [] student1 = {"1", "Zhang San", "18", "85.5"};
String [] student2 = {"2", "Li Si", "19", "90.0"};
writer.writeNext(student1);
writer.writeNext(student2);
// Write other student information into CSV files
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above example, we use the `csvwriter` class to create a CSV file, and use the` writenext` method to write records one by one.
In summary, the Java class library provides many powerful CSV frameworks, which can greatly simplify the processing of CSV data.Whether it is reading, writing, or modifying CSV files, these frameworks can help developers perform CSV data operations more efficiently.For more details, please refer to the corresponding library document.
