java如何在加载其他项之前清除listview

Question

我调用这个类是为了用下面的代码填充列表视图，问题是当调用它时，它会附加一个列表视图，我需要它来清除以前填充的数据。我该怎么做谢谢

  protected String doInBackground(String... args) {
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("Products", Products));
        JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
        Log.d("All Products: ", json.toString());
        try {
            int success = json.getInt(TAG_SUCCESS);
            if (success == 1) {
                products = json.getJSONArray(TAG_PRODUCTS);
                for (int i = 0; i < products.length(); i++) {
                    JSONObject c = products.getJSONObject(i);
                    String id = c.getString(TAG_PID);
                    String name = c.getString(TAG_NAME);
                    HashMap<String, String> map = new HashMap<String, String>();
                    map.put(TAG_PID, id);
                    map.put(TAG_NAME, name);
                    productsList.add(map);
                }
            } else {}
        } catch (JSONException e) {e.printStackTrace();}
        return null;
    }
    protected void onPostExecute(String file_url) {
        pDialog.dismiss();
        runOnUiThread(new Runnable() {
            public void run() {
                ListAdapter adapter = new SimpleAdapter(
                        Concurency_main.this, productsList,
                        R.layout.list_item, new String[] { TAG_PID,
                                TAG_NAME},
                        new int[] { R.id.user_id, R.id.user_name});
                setListAdapter(adapter);
            }
        });
      }

Answer 1

如果你添加到一个列表中，它会被追加。如果要删除所有，然后添加

Call list.clear() method to remove all the entries in the list.

protected String doInBackground(String... args) {
//remove all your list items
productsList.clear();
//Now your list is empty, try adding it now!

}