Java – is writer an atomic method?

I want to write some strings to the file Therefore, I use the bufferedwriter class Since many threads tend to write to this file, I wonder if the write and writeline methods are atomic

In addition, I want the program to write the output to multiple files, 100 lines each (such as file. Txt0, file. Txt1,...) for example

public class Main {
    static ExecutorService exec = Executors.newFixedThreadPool(5);
    BufferedWriter bw;
    public class myWriter implements Runnable {
        String str;
        myWriter (String str) {
            this.str = str;
        }
        public void run() {
            bw.write(str);
            bw.writeLine();
        }
    }
    public static void main(String[] args) {
        bw = new BufferedWriter(new  FileWriter("train.txt"));
        for (String arg: args)
            exec.execute(new myWriter(arg));
        exec.awaitTermination(100000,TimeUnit.MILLISECONDS);
    }
}

Can someone help me? If they are not atomic, how can I make them atomic and avoid collisions?

Solution

No, those are not atomic

If you want to write multiple tapes to the same file, use filelocks

try {
    // Get a file channel for the file
    File file = new File("filename");
    FileChannel channel = new RandomAccessFile(file,"rw").getChannel();

    // Use the file channel to create a lock on the file.
    // This method blocks until it can retrieve the lock.
    FileLock lock = channel.lock();

    // Try acquiring the lock without blocking. This method returns
    // null or throws an exception if the file is already locked.
    try {
        lock = channel.tryLock();
    } catch (OverlappingFileLockException e) {
        // File is already locked in this thread or virtual machine
    }

    // Release the lock
    lock.release();

    // Close the file
    channel.close();
} catch (Exception e) {
}