Android 更改数据库中的数据时，ListView上的新数据不会直接显示

这是我的第一篇帖子，我想问一些问题
我的应用程序使用JSON从/向数据库获取和发布数据，每次发布或获取数据时我都这样做

过程如下：

OrderListActivity-UpdateQtyActivity-OrderListActivity

OrderListActivity显示用户的订单，并可以更改其订单数量，当用户按下按钮

buttonOk

，它将处理数据并自动返回OrderListActivity以再次显示订单列表

但问题是，当用户从UpdateQtyActivity返回OrderListActivity时，listview中的数据没有改变，即使数据库中的数据改变了，它仍然显示旧数据

我需要返回到另一个活动或执行

OrderListActivity-UpdateQtyActivity-OrderListActivity

过程3次，以获得要更改的数据

我一直在尝试使用

adapter.notifyDataSetChanged（）

ArrayList.clear（）以前，但它没有给我什么

以下是我的OrderListActivity源代码：

public class OrderListActivity extends Activity implements OnClickListener {

ListView listProduct, listOrder, listDrink;
String FABId, FABPrice, FABName, ORDQty, SLSId;
TextView totalHarga, OrderPrice, QUANTITY;
String sum;

JSONObject jsonOrder;
Button buttonMin, buttonPlus, buttonOk;

SimpleAdapter adapter;

private ProgressDialog pDialog;
private String url_orderlist = "http://websitelink/get_order_details.php";
private static final String TAG_SUCCESS = "success";

private static final String TAG_FABID = "fab_id";
private static final String TAG_NAME = "fab_name";
private static final String TAG_PRICE = "fab_price";
private static final String TAG_SLSID = "sls_id";

private static final String TAG_ORD = "ord";
private static final String TAG_QTY = "ord_qty";
private static final String TAG_SUBTOTAL = "ord_subttl";
private static final String TAG_STATUS = "ord_status";
private static final String TAG_SUMSALES = "salesSum";
private static final String TAG_SUM = "sls_sum";

// Creating JSON Parser object
JSONParser jParser = new JSONParser();

ArrayList<HashMap<String, String>> productsListOrder = null;
HashMap<String, String> map = null;

// products JSONArray
JSONArray OrderList = null;
JSONObject SalesSummary = null;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.layout_ordlist);
    Intent i = getIntent();

    // getting product id (pid) from intent
    SLSId = i.getStringExtra(TAG_SLSID);

    productsListOrder = new ArrayList<HashMap<String, String>>();
    productsListOrder.remove(map);
    productsListOrder.isEmpty();
    productsListOrder.clear();
    TextView SLS = (TextView) findViewById(R.id.ordslsId);
    SLS.setText(SLSId);

    Button buttonBack = (Button) findViewById(R.id.buttonBack);
    buttonBack.setOnClickListener(this);
    buttonBack.setText("<");

    totalHarga = (TextView) findViewById(R.id.totalHarga);

    listOrder = (ListView) findViewById(R.id.orderList);

    adapter = new SimpleAdapter(OrderListActivity.this, productsListOrder,
            R.layout.list_order, new String[]{TAG_SLSID, TAG_FABID, TAG_STATUS,
            TAG_QTY, TAG_NAME, TAG_PRICE, TAG_SUBTOTAL},
            new int[]{R.id.slsId, R.id.ordFabId, R.id.ordStatus, R.id.ordQty, R.id.ordName,
                    R.id.ordPrice, R.id.ordSubtotal}) {
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            final View view = super.getView(position, convertView, parent);

            buttonMin = (Button) view.findViewById(R.id.buttonMinQty);
            buttonMin.setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View arg0) {
                    OrderPrice = (TextView) view.findViewById(R.id.ordPrice);
                    TextView OrderSubttl = (TextView) view.findViewById(R.id.ordSubtotal);
                    QUANTITY = (TextView) view.findViewById(R.id.ordQty);
                    int iQty = Integer.parseInt(QUANTITY.getText().toString());
                    int QUANTI = iQty - 1;

                    int iOrdPrice = Integer.parseInt(OrderPrice.getText().toString());
                    int PRICE = QUANTI*iOrdPrice;
                    OrderSubttl.setText(new Integer(PRICE).toString());
                    QUANTITY.setText(new Integer(QUANTI).toString());
                }
            });

            buttonPlus = (Button) view.findViewById(R.id.buttonPlusQty);
            buttonPlus.setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View arg0) {
                    jsonOrder.remove(TAG_SUCCESS);
                    OrderPrice = (TextView) view.findViewById(R.id.ordPrice);
                    TextView OrderSubttl = (TextView) view.findViewById(R.id.ordSubtotal);
                    QUANTITY = (TextView) view.findViewById(R.id.ordQty);
                    int iQty = Integer.parseInt(QUANTITY.getText().toString());
                    int QUANTI = iQty + 1;

                    int iOrdPrice = Integer.parseInt(OrderPrice.getText().toString());
                    int PRICE = QUANTI*iOrdPrice;
                    OrderSubttl.setText(new Integer(PRICE).toString());
                    QUANTITY.setText(new Integer(QUANTI).toString());
                }
            });

            buttonOk = (Button) view.findViewById(R.id.buttonOk);
            buttonOk.setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View arg0) {
                    SLSId = ((TextView) findViewById(R.id.slsId)).getText()
                            .toString();
                    FABId = ((TextView) view.findViewById(R.id.ordFabId)).getText()
                            .toString();
                    FABPrice = ((TextView) view.findViewById(R.id.ordPrice)).getText()
                            .toString();
                    ORDQty = ((TextView) view.findViewById(R.id.ordQty)).getText()
                            .toString();

                    Intent in = new Intent(OrderListActivity.this.getApplicationContext(),
                            UpdateQtyActivity.class);
                    in.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
                    in.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
                    // sending pid to next activity
                    in.putExtra(TAG_SLSID, SLSId);
                    in.putExtra(TAG_FABID, FABId);    // Starting new intent
                    in.putExtra(TAG_PRICE, FABPrice);    // Starting new intent.
                    in.putExtra(TAG_QTY, ORDQty);    // Starting new intent
                    in.putExtra(TAG_STATUS, "increase");

                    // starting new activity and expecting some response back
                    startActivityForResult(in,50);
                }
            });

            return view;
        }
    };

    new LoadOrder().execute();

}

public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    // if result code 100
    if (resultCode == 50) {
        // if result code 100 is received
        // means user edited/deleted product
        // reload this screen again
        Intent intent = getIntent();
        finish();
        startActivity(intent);
        } else {

    }

}

@Override
public void onBackPressed() {
    //super.onBackPressed(); // Comment this super call to avoid calling finish()
}


@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.buttonBack:
            // Create custom dialog object

            Intent in = new Intent(OrderListActivity.this.getApplicationContext(),
                    MainActivity.class);
            in.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
            // sending id to next activity
            in.putExtra(TAG_SLSID, SLSId);    // Starting new intent
            startActivity(in);
            finish();
            // closing this screen
            break;
    }

}

class LoadOrder extends AsyncTask<String, String, String> {

    /**
     * Before starting background thread Show Progress Dialog
     */
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(OrderListActivity.this);
        pDialog.setMessage("Memuat Pesanan...\n Tunggu Sebentar...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(false);
        pDialog.show();



    }

    /**
     * getting All products from url
     */
    protected String doInBackground(String... args) {
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("sls_id", SLSId));

        // getting JSON string from URL
        jsonOrder = jParser.makeHttpRequest(url_orderlist, "GET", params);


        // Check your log cat for JSON reponse
        Log.d("Orders : ", jsonOrder.toString());

        try {
            // Checking for SUCCESS TAG
            int successOrder = jsonOrder.getInt(TAG_SUCCESS);


            if (successOrder == 1) {
                // products found
                // Getting Array of Products
                OrderList = jsonOrder.getJSONArray(TAG_ORD);
                // looping through All Products
                for (int i = 0; i < OrderList.length(); i++) {
                    JSONObject c = OrderList.getJSONObject(i);

                    // Storing each json item in variable
                    String slsid = c.getString(TAG_SLSID);
                    String fabid = c.getString(TAG_FABID);
                    String name = c.getString(TAG_NAME);
                    String price = c.getString(TAG_PRICE);
                    String qty = c.getString(TAG_QTY);
                    String subtotal = c.getString(TAG_SUBTOTAL);
                    String status = c.getString(TAG_STATUS);

                    // creating new HashMap
                    map = new HashMap<String, String>();
                    // adding each child node to HashMap key => value
                    map.put(TAG_SLSID, slsid);
                    map.put(TAG_FABID, fabid);
                    map.put(TAG_NAME, name);
                    map.put(TAG_PRICE, price);
                    map.put(TAG_QTY, qty);
                    map.put(TAG_SUBTOTAL, subtotal);
                    map.put(TAG_STATUS, status);

                    // adding HashList to ArrayList
                    productsListOrder.add(map);
                }

                SalesSummary = jsonOrder.getJSONObject(TAG_SUMSALES);
                sum = SalesSummary.getString(TAG_SUM);


            } else {

            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return null;
    }

    /**
     * After completing background task Dismiss the progress dialog
     * *
     */
    protected void onPostExecute(String file_url) {
        runOnUiThread(new Runnable() {
            public void run() {
                // updating UI from Background Thread
                // updating listview
                Handler handler = new Handler();
                handler.postDelayed(new Runnable() {
                    public void run() {
                        pDialog.dismiss();
                        adapter.notifyDataSetChanged();
                        listOrder.getFirstVisiblePosition();
                        listOrder.getLastVisiblePosition();
                        listOrder.setAdapter(adapter);
                        ((SimpleAdapter)listOrder.getAdapter()).notifyDataSetChanged();
                        totalHarga.setText(sum);
                    }}, 3000);  // 3000 milliseconds
            }
        });
    }
} }

公共类OrderListActivity扩展活动实现OnClickListener{
ListView listProduct、listOrder、listDrink；
字符串FABId、FABPrice、FABName、ORDQty、SLSId；
text查看总价、订单价格、数量；
字符串和；
JSONObject jsonOrder；
按钮按钮分钟，按钮按钮lus，按钮nok；
SimpleAdapter适配器；
私人对话；
私有字符串url_orderlist=”http://websitelink/get_order_details.php";
私有静态最终字符串标记_SUCCESS=“SUCCESS”；
私有静态最终字符串TAG_FABID=“fab_id”；
私有静态最终字符串TAG_NAME=“fab_NAME”；
私有静态最终字符串TAG_PRICE=“fab_PRICE”；
私有静态最终字符串标记\u SLSID=“sls\u id”；
专用静态最终字符串标记_ORD=“ORD”；
专用静态最终字符串标记\u QTY=“ord\u QTY”；
私有静态最终字符串标记\u SUBTOTAL=“ord\u subttl”；
专用静态最终字符串标记_STATUS=“ord_STATUS”；
私有静态最终字符串标记_SUMSALES=“salesSum”；
私有静态最终字符串标记\u SUM=“sls\u SUM”；
//创建JSON解析器对象
JSONParser jParser=新的JSONParser（）；
ArrayList productsListOrder=null；
HashMap=null；
//产品JSONArray
JSONArray OrderList=null；
JSONObject SalesSummary=null；
@凌驾
创建时的公共void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.layout\u ordlist）；
Intent i=getIntent（）；
//从intent获取产品id（pid）
SLSId=i.getStringExtra（标记SLSId）；
ProductsListStorder=新的ArrayList（）；
productsListOrder.remove（映射）；
productsListOrder.isEmpty（）；
productsListStorder.clear（）；
TextView SLS=（TextView）findViewById（R.id.ordslsId）；
SLS.setText（SLSId）；
Button buttonBack=（Button）findViewById（R.id.buttonBack）；
setOnClickListener（这个）；
buttonBack.setText（“你能用这种方式试试吗

public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    // if result code 50
    if (resultCode == 50) {
        // if result code 50 is received
        // means user edited/deleted product
        // **reload previous data**
        new LoadOrder().execute();
    }
}

更新：您需要清除LoadOrder类的onPreExecute方法中的ProductsStorder ArrayList

/**
 * Before starting background thread Show Progress Dialog
 */
@Override
protected void onPreExecute() {
    super.onPreExecute();
    pDialog = new ProgressDialog(OrderListActivity.this);
    pDialog.setMessage("Memuat Pesanan...\n Tunggu Sebentar...");
    pDialog.setIndeterminate(false);
    pDialog.setCancelable(false);
    pDialog.show();

    productsListOrder.clear();
}

请查看更新，并让我知道。并确保UpdateQtyActivity类中的值发生更改。值发生更改，因为数据库中的数据也发生了更改，如果UpdateQtyActivity中的值没有更改，数据库也不会更改，先生。嗯，我想我将尝试另一种方法解决此问题，谢谢您的回复，我将检查此答案最有帮助的是，我解决了我的问题，我对我的应用程序使用了不同的方法，因此我不需要移动到另一个活动并返回，我只需将我的值发送到asynctask进行处理，并使用您的方式刷新我的arraylist，非常感谢您：D
/**
 * Before starting background thread Show Progress Dialog
 */
@Override
protected void onPreExecute() {
    super.onPreExecute();
    pDialog = new ProgressDialog(OrderListActivity.this);
    pDialog.setMessage("Memuat Pesanan...\n Tunggu Sebentar...");
    pDialog.setIndeterminate(false);
    pDialog.setCancelable(false);
    pDialog.show();

    productsListOrder.clear();
}