android UnsupportedOperationException in ArrayAdapter<String>

Question

I am trying to create an onDisimiss listener to my app as for now this is what i have

The activity

public class listview_test extends Activity {
ListView list;
String[] web = {
        "Google Plus",
        "Twitter",
        "Windows",
} ;
Integer[] imageId = {
        R.drawable.ic_launcher,
        R.drawable.icon,
        R.drawable.ic_launcher,
};
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.list_test);
    final CustomList adapter = new
            CustomList(listview_test.this, web, imageId);
    list=(ListView)findViewById(R.id.list);
    list.setAdapter(adapter);
    list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                                int position, long id) {
            Toast.makeText(listview_test.this, "You Clicked at " +web[+ position], Toast.LENGTH_SHORT).show();
        }
    });
    SwipeDismissListViewTouchListener touchListener =
            new SwipeDismissListViewTouchListener(
                    list,
                    new SwipeDismissListViewTouchListener.DismissCallbacks() {
                        @Override
                        public boolean canDismiss(int position) {
                            return true;
                        }

                        @Override
                        public void onDismiss(ListView listView, int[] reverseSortedPositions) {
                            for (int position : reverseSortedPositions) {
                                adapter.remove(adapter.getItem(position));
                            }
                            adapter.notifyDataSetChanged();
                        }
                    }
            );
    list.setOnTouchListener(touchListener);
    // Setting this scroll listener is required to ensure that during ListView scrolling,
    // we don't look for swipes.
    list.setOnScrollListener(touchListener.makeScrollListener());
}
}

And the custom adapter

public class CustomList extends ArrayAdapter<String>{
private final Activity context;
private final String[] web;
private final Integer[] imageId;
public CustomList(Activity context,
                  String[] web, Integer[] imageId) {
    super(context, R.layout.weather_item, web);
    this.context = context;
    this.web = web;
    this.imageId = imageId;
}
@Override
public View getView(int position, View view, ViewGroup parent) {
    LayoutInflater inflater = context.getLayoutInflater();
    View rowView= inflater.inflate(R.layout.weather_item, null, true);
    TextView txtTitle = (TextView) rowView.findViewById(R.id.city);
    ImageView imageView = (ImageView) rowView.findViewById(R.id.info_image);
    txtTitle.setText(web[position]);
    imageView.setImageResource(imageId[position]);
    return rowView;
}

For some reason every time i am swiping an item to dismiss it force closes and gives me this exception

    java.lang.UnsupportedOperationException

In this line

adapter.remove(adapter.getItem(position));

A--C · Accepted Answer · 2014-07-16 01:21:30Z

3

java.lang.UnsupportedOperationException

is thrown when you back an Adapter by an array or non-modifiable List. Since you cannot change their size, deleting is impossible.

Instead, modify your Adapter so it accepts a List instead of an array and make sure that the List you pass off is fully flexible.

Something like

List <String> web = new ArrayList <String> ();
web.add ("Google Plus");
web.add ("Twitter");
//etc.

is enough to ensure a flexible list.

This means that your CustomList adapter should also call up to the superclass constructor that also accepts in a List, which in this case is

public ArrayAdapter (Context context, int resource, List<T> objects)

For more information refer to the ArrayAdapter documentation.

edited Jul 16, 2014 at 1:21

answered Jul 16, 2014 at 1:15

A--C

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2 Comments

user3068269 Over a year ago

so instead of an "ArrayAdapter" i should use ListAdapter?

A--C Over a year ago

@user3068269 no, ListAdapter is an interface implemented by ArrayAdapter. Continue to use ArrayAdapter but change the super call.

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