Serializing ArrayList android not working

Question

UPDATE: After a bit of testing I've determined the file itself isnt being created, at least according to the file.exists check anyway. Any ideas?

Hi I'm trying to serialize an arraylist when my app is exited and read it back when its resumed. It doesnt seem to be creating the file.

Here is my code.

protected void onPause() {
    super.onPause();

    if(!myArrayList.isEmpty())
    {
        final String FILENAME = "myfile.bin";
        try{
            FileOutputStream fos;

            fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);

            //FileOutputStream fileStream = new FileOutputStream(FILENAME);
            ObjectOutputStream os = new ObjectOutputStream(fos);
            os.writeObject(myArrayList);
            os.flush();
            os.close();
        } catch (FileNotFoundException e) {
                e.printStackTrace();
            }catch(IOException e){
                e.printStackTrace();
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
    }
}

@SuppressWarnings("unchecked")
    @Override
    protected void onResume() {
        super.onResume();

    File file = new File("myfile.bin");
    if(file.exists()){
        final String FILENAME="myfile.bin";
        try{
            FileInputStream fileStream = new FileInputStream(FILENAME);
            ObjectInputStream os = new ObjectInputStream(fileStream);
            myArrayList = (ArrayList<MyObject>)os.readObject();
            os.close();
        } catch (FileNotFoundException e) {
                e.printStackTrace();
            }catch(IOException e){
                e.printStackTrace();
        }
    }




}

Any ideas? My MyObject class implements serializable.

The e.getMessage() in your catch statements does absolutely nothing so you are essentially silently ignoring any thrown exceptions. Improving your error handling will help you pinpoint the issue. — Chris Knight
– Chris Knight, Commented Mar 23, 2011 at 21:47
@Chris Knight Added some more handling filenotfound and ioexcpetion still no errors in logcat/error log. — Nicklas O
– Nicklas O, Commented Mar 23, 2011 at 21:51
Aside: you should definitely consider moving the IO you are doing into Loaders or AsyncTasks — Jon Willis
– Jon Willis, Commented Mar 23, 2011 at 22:06
I've never developed Andriod before, but can you not put System.out.println statements after each step in the code above to verify what is (or is not) happening? — Chris Knight
– Chris Knight, Commented Mar 23, 2011 at 22:09

bstpierre · Accepted Answer · 2011-03-25 13:10:12Z

1

Got it to work by changing FileInputStream fileStream = new FileInputStream(FILENAME) to FileInputStream fileStream= openFileInput(FILENAME).

edited Mar 25, 2011 at 13:10

bstpierre

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answered Mar 24, 2011 at 23:02

Nicklas O

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1 Comment

Jason Plank Over a year ago

Glad to see you solved your problem! Don't forget to mark your answer as accepted by clicking the check mark at left.

Naveen · Accepted Answer · 2011-03-23 21:56:47Z

0

os.writeObject(myArrayList);
os.flush();
os.close();

Try os.close() immediately after writeObject, it should call flush() anyways.

answered Mar 23, 2011 at 21:56

Naveen

1161 silver badge3 bronze badges

3 Comments

Nicklas O Over a year ago

That was my original code, I added the flush after seeing it as a suggestion somewhere on google. Still didn't work.

Naveen Over a year ago

confirm if MyObject is in the classpath, see if simple ArrayList<String> works.

Nicklas O Over a year ago

The class is in the same package/directory of the main program if thats what you mean?

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