从arraylist中删除项目时，无法使用notifydatasetchanged刷新listview

Question

Im having a problem beeing able to refresh my listview when deleting items on longclick. It seems to be that the items from the arraylist are being deleted, yet the adapter is'nt refreshing immediately, even though I'm calling adapter.notifydatasetchanged. Can't figure out why the adapter will not set the new values. Any help very much appreciated.

public class MySongBookActivity extends ActionBarActivity {
ArrayList<String> test;
ListView list;
private static final String TAG = "MySongBookActivity";
CustomAdapter adapter;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my_song_book);

    try {
        DataBaseHandler db = new DataBaseHandler(this);
        final ListView list = (ListView) findViewById(R.id.mySongBookListView);
        list.setDivider(null);
        TinyDB tinydb = new TinyDB(getBaseContext());
        final ArrayList<String> test = tinydb.getList("hello");

        String[] values = test.toArray(new String[0]);

        final CustomAdapter adapter = new CustomAdapter(this,
                R.layout.list_item_row, values);

        list.setAdapter(adapter);

        list.setOnItemClickListener(new OnItemClickListener() {

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

                String data = (String) list.getItemAtPosition(position);
                data.toString();
                int hej = list.getCheckedItemPosition();

                Intent i = new Intent(MySongBookActivity.this,
                        SBLyricsActivity.class);
                i.putExtra("titelName", data);
                i.putExtra("pos", position);

                startActivity(i);

            }

        });
        list.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> av, View view,
                    int position, long id) {
                return onLongListItemClick(view, position, id);
            }

            protected boolean onLongListItemClick(View view, int position,
                    long id) {
                Log.i(TAG, "onLongListItemClick id=" + position);
                test.remove(position);
                list.setAdapter(adapter);
                adapter.notifyDataSetChanged();

                Log.i("test.size()", "" + test.size());
                return true;
            }

        });



    } catch (Exception ex) {
        ex.printStackTrace();
    }

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment()).commit();
    }

}


@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.my_song_book, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_my_song_book,
                container, false);
        return rootView;
    }
}

}

My adapter class:

public class CustomAdapter extends BaseAdapter {

private String[] data;
private Context context;

public CustomAdapter(Context context,int resourceId, String[] data1) {
    super();
    this.data = data1;

    this.context = context;
}

@Override
public int getCount() {
    return data.length;
}

@Override
public Object getItem(int position) {
    return data[position];
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View rowView = LayoutInflater.from(context).
            inflate(R.layout.list_item_row, parent, false);

    TextView text1 = (TextView) rowView.findViewById(R.id.txtTitle);


    text1.setText(data[position]);


    return rowView;
}

}

Answer 1

Your adapter is bound to String[] values = test.toArray(new String[0]); , that is a copy of test . So when you change test , values don't change and so doesn't the content of the list .

What you can do is to bind adapter to the ArrayList itself:

public CustomAdapter(Context context,int resourceId, ArrayList<String> data1) {
    this.data = data1; // this.data should be List<String>
    this.context = context;
}

// change other methods accordingly

So to initialize the adapter you do:

final ArrayList<String> test = tinydb.getList("hello");

final CustomAdapter adapter = new CustomAdapter(this,
        R.layout.list_item_row, test);

Also, you don't have to call list.setAdapter(adapter); in onLongListItemClick() (I think you did it out of despair)