how to add item to Spinner's ArrayAdapter?

Question

i had a EditText , a button and a spinner . When click the button , the spinner will add a new item with name you entered in the EditText. But here is the question, my adapter.add() method seems doesn't work...here is my code:

public class Spr extends Activity {
Button bt1;
EditText et;
ArrayAdapter<CharSequence> adapter;
Spinner spinner;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    bt1 = (Button)this.findViewById(R.id.bt1);
    et = (EditText)this.findViewById(R.id.et);  
    spinner = (Spinner)this.findViewById(R.id.spr);

    adapter = ArrayAdapter.createFromResource(
            this, R.array.planets_array, android.R.layout.simple_spinner_item);

    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

    spinner.setAdapter(adapter);

    bt1.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            String temp = et.getText().toString();

            adapter.add(temp);
            adapter.notifyDataSetChanged();
            spinner.setAdapter(adapter);

        }
    });


    spinner.setOnItemSelectedListener(new Spinner.OnItemSelectedListener(){

        @Override
        public void onItemSelected(AdapterView<?> parent, View view,
                int pos, long id) {

            Toast.makeText(parent.getContext(), "The planet is " +
                      parent.getItemAtPosition(pos).toString(), Toast.LENGTH_LONG).show();

        }

        @Override
        public void onNothingSelected(AdapterView<?> arg0) {

        }});
}

}

thanks! ...still waitting

Answer 1

I believe this is working as designed, but not as expected. ArrayAdapter used to only take an array, but the list constructor was added later. I'm guessing its just doing a toArray() on your list. This is why you have to either call add on the adapter, or create a new adapter when your List changes.

Answer 2

I tried this and I am getting an error message:
07-25 14:18:44.221: ERROR/AndroidRuntime(2180): Caused by: java.lang.UnsupportedOperationException 07-25 14:18:44.221: ERROR/AndroidRuntime(2180): at java.util.AbstractList.add(AbstractList.java:411)

What I did is to add the "add" method after setAdapter. See Below:

adapter = ArrayAdapter.createFromResource( this, R.array.planets_array, android.R.layout.simple_spinner_item);

adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

spinner.setAdapter(adapter);

String temp = et.getText().toString();

adapter.add(temp);
adapter.notifyDataSetChanged();
spinner.setAdapter(adapter);

Answer 3

Hi I was wondering if you have solved this problem eventually? I ran into an exact problem like yours and am researching for a solution...thanks.

HT

Answer 4

When you have created your ArrayAdapter you haven't assigned a resizeable List to it, so when you do add() it cannot increment the size of it and throws a UnsupportedOperationException.

Try something like this:

List<CharSequence> planets = new ArrayList<CharSequence>();
adapter = new ArrayAdapter<CharSequence>(context,
                       R.array.planets_array, planets);
//now you can call adapter.add()

You should use a List. With an Array such as CharSequence[] you would get the same UnsupportedOperationException exception.