Question

I want to show an empty list view, which is then populated by user input. I have the UI flow working, and I populate a list of my custom objects after the user enters some information via a view which is invoked through setContentView (i.e. no a new Activity).

I take the input and add it to a list, which I want to be summarised on the ListView. However, whenever I add to the list and/or the ArrayAdapter and call adapter.notifyDataSetChanged() it does not do what I want. The ListView is still empty. Argh! It’s driving me insane!

@Override
public void onCreate(Bundle blah) {
    ListView listView = (ListView) findViewById(R.id.results_list);
    listView.setAdapter(new ArrayAdapter(this, android.R.layout.simple_list_item_1, list));
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case R.id.mnu_add:
        final Activity act = this;
        setContentView(R.layout.record_details);// the sub-view that takes the user input
        // the button on the form to 'add' details:-
        ((Button) findViewById(R.id.recored_details_add_btn))
        .setOnClickListener(
            new OnClickListener() {
            public void onClick(View v) {
                    // get input from widgets 
                    list.add(someObject);
                    ((ArrayAdapter<Object>) listView.getAdapter()).notifyDataSetChanged();
                    setContentView(R.layout.list_view);

                }
            }
        );
        ((ArrayAdapter<Object>) listView.getAdapter()).notifyDataSetChanged();
        break;
    }
    return true;
}

Please, save me from my misery and inform me of my stupidty?

Thanks in advance.

Answer 1

public void onClick(View v) {
    // get input from widgets 
    list.add(someObject);
    ((ArrayAdapter<Object>) listView.getAdapter()).notifyDataSetChanged();
    setContentView(R.layout.list_view);

Is it possible that this setContentView in the onClick handler is creating a new instance of the list view widget (with no adapter) or reinitializing the list view (clearing the adapter)?

Try putting something in the list initially in onCreate and then see if it disappears when you hit the button.

I haven’t seen any code (although I’m a relative newbie) that switches views within the activity’s lifetime to bring up essentially bring up different pages – most use a separate activity.

Edit:

OP asks:

Thanks…So how can I get what I want? The list I’m backing the adapter with is static; should I just use activities instead and rely on onCreate loading from the static field?

Some options:

1. Use separate activities

2. Re-associate the adapter (call setAdapter again) – probably a bad idea

3. Declare both layouts in the same file. You’ll hide one and unhide the other to switch between views rather can calling setContentView. This is similar to how ListView layout works (one for when the list is empty and one for when it is not). I think I’ve seen an example of this somewhere on the net, but I don’t have a reference right now.