如何使用Java多线程概念将多个csv文件合并为一个文件

import java.io.*;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.List;

public class CsvFileReader implements Runnable {
    private String inputFilePath;
    private String outputFilePath;

    public CsvFileReader(String inputFilePath, String outputFilePath) {
        this.inputFilePath = inputFilePath;
        this.outputFilePath = outputFilePath;
    }

    @Override
    public void run() {
        try {
            List<String> lines = Files.readAllLines(Paths.get(inputFilePath));
            synchronized (CsvFileMerger.class) {
                Files.write(Paths.get(outputFilePath), lines, StandardOpenOption.APPEND);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.util.ArrayList;
import java.util.List;

public class CsvFileMerger {
    public static void main(String[] args) {
        String[] inputFiles = {"file1.csv", "file2.csv", "file3.csv"};
        String outputFile = "merged_output.csv";

        List<Thread> threads = new ArrayList<>();

        for (String inputFile : inputFiles) {
            Thread thread = new Thread(new CsvFileReader(inputFile, outputFile));
            threads.add(thread);
            thread.start();
        }

        for (Thread thread : threads) {
            try {
                thread.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        System.out.println("CSV files have been merged.");
    }
}