Question

I have a an app with an IM style page, the text is displayed using a custom listview

When I leave the activity and come back I want to still have the listview with all my data in it. SO far I have tried saving the contents of my arraylist using onSavedInstance and onRestoredInstance then setting the adapter again in onRestoredInstance but that doesn’t work.

Here is my code for my activity:

private ArrayList<String> nameList = new ArrayList<String>();
    private ArrayList<String> messageList = new ArrayList<String>();
    private ArrayList<String> timeList = new ArrayList<String>();

    Button send = (Button) findViewById(R.id.chat_send);
    EditText send = (EditText) findViewById(R.id.edit_text);
    ListView chat_list = (ListView) findViewById(R.id.chat_list);
    MyCustomArrayAdapter myArrayAdapter = new MyCustomArrayAdapter(this, messageList, nameList,
            timeList, receiverName, senderName, language_chosen);

    chat_list.setAdapter(myArrayAdapter);       

    send.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            String new_text = edit_text.getText().toString();
            String sys_time = new Time(System.currentTimeMillis())
                    .toString();
            timeList.add(sys_time);
            messageList.add(new_text);
            nameList.add(username);
            myArrayAdapter.notifyDataSetChanged();
            chat_list.setSelection(chat_list.getChildCount()-1);
        }
    });

And here is the code for my Adapter

public MyCustomArrayAdapter(Context context, ArrayList<String> planetList,
        ArrayList<String> NameList, ArrayList<String> TimeList,
        String receiver, String sender, String language) {
    super(context, R.layout.custom_chat_layout, planetList);
    this.context = context;
    messageList = planetList;
    nameList = NameList;
    timeList = TimeList;
    receiverName = receiver;
    senderName = sender;
    language_chosen = language;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    LayoutInflater inflater = (LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    holder = new ViewHolder();

    rowView = inflater.inflate(R.layout.custom_chat_layout, parent, false);
    holder.chat_name = (TextView) rowView
            .findViewById(R.id.custom_chat_name);
    holder.chat_time = (TextView) rowView
            .findViewById(R.id.custom_chat_timestamp);
    holder.chat_text = (TextView) rowView
            .findViewById(R.id.custom_chat_text);


    holder.chat_name.setText(nameList.get(position));
    holder.chat_time.setText(timeList.get(position));
    holder.chat_text.setText(messageList.get(position));

    return rowView;
}

static class ViewHolder {
    TextView chat_name;
    TextView chat_time;
    TextView chat_text;
    RelativeLayout relative;
    RelativeLayout relative1;
}

Answer 1

You should save the data in onPause and re-populate the adapter in onResume. Things like instant messages should be saved to persistent data storage (for example, an SQLite database), and then loaded with a CursorAdapter. A lot of the details of maintaining the data load across the Activity lifecycle can be abstracted out by making use of the LoaderManager and loading the data with a CursorLoader instead.

It also sounds like you want to have a Service running in the background that can receive messages and save instant messages to the data store even when the Activity isn’t in focus.