How to write an ArrayList to file and retrieve it?

Question

now im trying to use this

FileOutputStream fos = getContext().openFileOutput("CalEvents", Context.MODE_PRIVATE);
    ObjectOutputStream oos = new ObjectOutputStream(fos);
    oos.writeObject(returnlist);
    oos.close();

in order to save "returnlist" which is an ArrayList to the file "CalEvents" now my question is , is that the right way to do it? and how do i retrieve the list back?

thanks in advance

Answer 1

Is this what you want to do ?

FileInputStream fis;
try {
    fis = openFileInput("CalEvents");
    ObjectInputStream ois = new ObjectInputStream(fis);
    ArrayList<Object> returnlist = (ArrayList<Object>) ois.readObject();
    ois.close();
} catch (FileNotFoundException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
} catch (ClassNotFoundException e) {
    e.printStackTrace();
}

EDIT: Can be simplified:

FileInputStream fis;
try {
    fis = openFileInput("CalEvents");
    ObjectInputStream ois = new ObjectInputStream(fis);
    ArrayList<Object> returnlist = (ArrayList<Object>) ois.readObject();
    ois.close();
} catch (Exception e) {
    e.printStackTrace();
}

Assuming that you are in a class which extends Context (like Activity). If not, then you will have to call the openFileInput() method on an object which extends Context.

Answer 2

Use this method to write your Arraylist in a file

public static void write(Context context, Object nameOfClass) {
    File directory = new File(context.getFilesDir().getAbsolutePath()
            + File.separator + "serlization");
    if (!directory.exists()) {
        directory.mkdirs();
    }

    String filename = "MessgeScreenList.srl";
    ObjectOutput out = null;

    try {
        out = new ObjectOutputStream(new FileOutputStream(directory
                + File.separator + filename));
        out.writeObject(nameOfClass);
        out.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

Complete example here, with Read method