Question

I have a following Spinner in the OnCreate Method:

    spinnerArrayAdapter = new ArrayAdapter<String>(this,   android.R.layout.simple_spinner_item, accounts);
        spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); // The drop down view
        spinner.setAdapter(spinnerArrayAdapter); 
        spinner.setOnItemSelectedListener(this);

and I want add some entries to the Spinner in a other Method like this:

spinnerArrayAdapter.add(value.toString());
spinner.setAdapter(spinnerArrayAdapter); 

but the app crashes. What can I do?
Thanks!

Answer 1

You have 2 possibilities:

Either:

in place where you are about to add new record to adapter:
spinnerArrayAdapter.add("Your new item");
spinnerArrayAdapter.notifyDataSetChanged();

Or:

In your onCreate when initialising adapter add spinnerArrayAdapter.setNotifyOnChange(true);
when you want to add record to adapter later simply call spinnerArrayAdapter.add("Your new item");. No need to call notifyDataSetChanged() as it has been called by add internally.

in both cases you don’t have to re-assign adapter to spinner.

if you initialize your adapter with array, add method will raise exception, as what adapter stores internally is (List<T>) Arrays.asList(objects) where objects is the array you provided in constructor. asList returns the List interface wrapper implementation over the array so it does not support add opeation. In order to be able to use adapter’s add method you must provide the backing data as List with supported add/remove methods – i suggest ArrayList.

so in your case init it like that:

spinnerArrayAdapter = new ArrayAdapter<String>(
        this, android.R.layout.simple_spinner_item, 
        new ArrayList<String>(Arrays.asList(accounts)));

or longer but more efficent (e.g. you do not create
overhead list object to be abandoned a moment later)

final int length = accounts.length;
ArrayList<String> backingData = new ArrayList<String>(length);
for(int i=0; i<length; i++) {
    backingData.add(i, accounts[i]);
}
spinnerArrayAdapter = new ArrayAdapter<String>(
        this, android.R.layout.simple_spinner_item, backingData);