如何从ArrayAdapter类更新ListView？

Question

I have a ArrayList which uses an ArrayAdapter to display its list data in a ListView

Each ListView item has a single TextView and a Button. Clicking the button updates the data held in the ArrayList and this works fine. How do I get the ListView to update at the same time? I know how to do this from the Activity where the ArrayAdapter is created because I can call itemAdapter.notifyDataSetChanged() to update the view. But I don't see how I can do it from within the ArrayAdapter class (ie ListItemAdapter) when Button myButton is clicked.

Any ideas? Thanks.

StartActivity Class

public class StartActivity extends Activity {

ArrayList<DataRecord> datalist;
ListView listView;
ListItemAdapter itemAdapter;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.list_screen);

    datalist = new ArrayList<DataRecord>();

    listView = (ListView) findViewById(R.id.ListViewId);
    itemAdapter = new ListItemAdapter(this, android.R.layout.simple_list_item_1, datalist);
    listView.setAdapter(itemAdapter);

    DataRecord dataRecord = new DataRecord("Data Item 1 ");
    datalist.add(dataRecord);

    dataRecord = new DataRecord("Data Item 2 ");
    datalist.add(dataRecord);

    dataRecord = new DataRecord("Data Item 3");
    datalist.add(dataRecord);

    itemAdapter.notifyDataSetChanged();
}
}

ListItemAdapter Class

public class ListItemAdapter extends ArrayAdapter<DataRecord> {
private ArrayList<DataRecord> datalist;

public ListItemAdapter(Context context, int textViewResourceId, ArrayList<DataRecord> datalist) {
    super(context, textViewResourceId, datalist);
    this.datalist = datalist;
}

@Override
public View getView(final int position, View convertView, final ViewGroup parent) {
    View v = convertView;
    if (v == null) {
        LayoutInflater vi = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        v = vi.inflate(R.layout.list_row, null);

    }
    Button mybutton = (Button)v.findViewById(R.id.pushBtn);

    final DataRecord dataitem = datalist.get(position);

    mybutton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            dataitem.information = "Hello";
            for (int i = 0; i < datalist.size(); i++) {
                Log.d("Item", datalist.get(i).information);   // this shows the ArrayList gets updated
            }
        }
    });


    if (dataitem != null) {
        TextView listText = (TextView) v.findViewById(R.id.list_text);

        if (listText != null) {
            listText.setText(dataitem.information);
        }

    }
    return v;
}
}

Answer 1

Just use the same method in the adapter, but without the object reference, since you are in the context of the object

mybutton.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        dataitem.information = "Hello";
        notifyDataSetChanged();
    }
});

Answer 2

try this

mybutton.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View view) {
     //
     //update data
     //
     this.notifyDataSetChanged();
  }
});

Answer 3

mybutton.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        dataitem.information = "Hello";
        ListItemAdapter.this.notifyDataSetChanged();
    }
});