Is it possible to write to the same file from different methods?

I have the following method:

public static void writeContestantsToFile(ArrayList<Contestant> contestants) throws IOException {
    FileOutputStream fos = new FileOutputStream("minos.dat");
    ObjectOutputStream oos = new ObjectOutputStream(fos);

    oos.writeObject(contestants);
    oos.flush();
    oos.close();
}

But I am wondering whether or not I can write to t开发者_如何转开发he file minos.dat again with another arraylist? For example have another method like this:

public static void writeContestantsToFile(ArrayList<Times> times) throws IOException {
    FileOutputStream fos = new FileOutputStream("minos.dat");
    ObjectOutputStream oos = new ObjectOutputStream(fos);

    oos.writeObject(times);
    oos.flush();
    oos.close();
}

Will I be able to retrieve both the times arraylist and contestants? Or do I need to write to separate files?

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You can, but if you don't want to override the content of the file, but only append, open it like that:

FileOutputStream fos = new FileOutputStream("minos.dat", true);

(using this constructor)

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If you mean sequentially in one thread then you use @MByD solution. Its called appending. If this is multithreaded then you will need to block and synchronize.

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Not in the case of object streams. Without special measures you cannot append to a file using object output streams. You must:

• leave the file open
• synchronize access to it
• use the same ObjectOutputStream for the life of the process
• and ensure it is closed when you exit.