Java流groupby和Java同时用于csv导出

import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public class GroupByExample {
    public static void main(String[] args) {
        // 创建一个包含多个Person对象的列表
        List<Person> persons = Arrays.asList(
                new Person("Alice", 25),
                new Person("Bob", 30),
                new Person("Alice", 35),
                new Person("Bob", 40)
        );

        // 使用groupingBy方法按照Person对象的name属性进行分组
        Map<String, List<Person>> groupedPersons = persons.stream()
                .collect(Collectors.groupingBy(Person::getName));

        // 打印分组结果
        groupedPersons.forEach((name, group) -> {
            System.out.println("Group: " + name);
            group.forEach(System.out::println);
            System.out.println();
        });
    }

    static class Person {
        private String name;
        private int age;

        public Person(String name, int age) {
            this.name = name;
            this.age = age;
        }

        public String getName() {
            return name;
        }

        public int getAge() {
            return age;
        }

        @Override
        public String toString() {
            return "Person{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    '}';
        }
    }
}

import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVPrinter;

import java.io.FileWriter;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;

public class CsvExportExample {
    public static void main(String[] args) {
        // 创建要导出的数据列表
        List<List<String>> data = Arrays.asList(
                Arrays.asList("Name", "Age", "Country"),
                Arrays.asList("Alice", "25", "USA"),
                Arrays.asList("Bob", "30", "Canada"),
                Arrays.asList("Charlie", "35", "UK")
        );

        // 指定CSV文件的路径
        String csvFilePath = "output.csv";

        try (FileWriter fileWriter = new FileWriter(csvFilePath);
             CSVPrinter csvPrinter = new CSVPrinter(fileWriter, CSVFormat.DEFAULT)) {

            // 写入数据到CSV文件
            for (List<String> rowData : data) {
                csvPrinter.printRecord(rowData);
            }

            System.out.println("CSV file exported successfully.");

        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}