In -depth analysis of the technical principles of Table/IO CSV SUPPORT framework in the Java library
Table/IO CSV SUPPORT framework technical principles and examples in the Java class library
The Table/IO CSV SUPPORT framework in the Java class library is an important tool for processing CSV files. It provides a simple and flexible way to read and write CSV files.In this article, we will explore the technical principles of this framework and provide some Java code examples to help readers better understand.
CSV (comma separation value) is a commonly used file format that is used to store and exchange some simple table data.It is separated by a comma to separate each value to store a line of data.The Table/IO CSV SUPPORT framework in the Java class library aims to simplify the read and write operation of the CSV file, and provide many extension functions and options.
To use Table/IO CSV SUUPPORT framework, you need to import the corresponding packages first.In the Java 8 and above versions, the following ways can be imported:
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import com.opencsv.CSVReader;
import com.opencsv.CSVReaderBuilder;
import com.opencsv.CSVWriter;
Next, we will introduce the two main functions of the framework in detail: read CSV files and write to CSV files.
## Reading CSV file
To read the CSV file, we need to create a CSVReader object and specify the file path to be read.We can then read data with the method provided by the CSVReader object.
The following is an example. How to read a CSV file called "Example.csv" and print the data of each line:
try (CSVReader reader = new CSVReader(new FileReader("example.csv"))) {
String[] nextLine;
while ((nextLine = reader.readNext()) != null) {
// Print each row of data
for (String value : nextLine) {
System.out.print(value + " ");
}
System.out.println();
}
} catch (IOException e) {
e.printStackTrace();
}
In the above code, we use the Readnext () method of the CSVReader object to read the data routinely and store each row of data in a String array.We then use a nested cycle to traverse each line of data and print it out.
## Write into CSV file
To write the CSV file, we need to create a CSVWriter object and specify the file path to be written.We can then write the data with the method provided by the CSVWriter object.
The following is an example. Demonstration of how to write some data into a CSV file called "Output.csv"::
try (CSVWriter writer = new CSVWriter(new FileWriter("output.csv"))) {
// Create a two -dimensional array, indicating the data to be written
String[][] data = {{"Name", "Age", "City"}, {"John", "25", "New York"}, {"Alice", "30", "London"}};
// data input
writer.writeAll(List.of(data).stream().map(arr -> (String[])arr).collect(Collectors.toList()));
} catch (IOException e) {
e.printStackTrace();
}
In the above code, we first created a two -dimensional array called "Data" for storing data to be written.We then write the data into the CSV file with the Writall () method of the CSVWriter object.
In addition to basic reading and writing operations, the Table/IO CSV Support framework also provides many other functions, such as processing CSV files with heads, customizers or quotes, jumps or columns, etc.These functions need to be configured and used according to specific needs.
In summary, the Table/IO CSV SUPPORT framework is a powerful and easy -to -use Java class library. It simplifies the read and write operation of the CSV file and provides many convenient functions.It is hoped that the introduction and example of this article can help readers better understand the technical principles and use of the framework.
