我正在从localhost服务器的listview中加载我的数据。我想在textview（locationCount）中显示计数。有任何想法吗？
我的listview有id / list，它是为加载产品的异步类引用的。因此，如果您将其视为普通列表视图或稍有不同，我会感到有点困惑？
我的数据库中有20个条目显示，因此计数应为20，但是当我删除条目时，计数应为19，如果我添加，则为21。请解释一下？
类别： 公共类ViewAllLocations扩展了ListActivity {
String id;
// Progress Dialog
private ProgressDialog pDialog;
// JSON parser class
JSONParser jsonParser = new JSONParser();
ArrayList<HashMap<String, String>> profileList;
// url to get all products list
private static String url_all_profile = "http://MYIP:8888/android_connect/get_all_location.php";
// url to delete product
private static final String url_delete_profile = "http://MYIP:8888/android_connect/delete_location.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_LOCATION = "Location";
private static final String TAG_ID = "id";
private static final String TAG_LATITUDE = "latitude";
private static final String TAG_LONGITUDE = "longitude";
// products JSONArray
JSONArray userprofile = null;
TextView locationCount;
int count = 0;
Button deleteLocation;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_all_locations);
// Hashmap for ListView
profileList = new ArrayList<HashMap<String, String>>();
deleteLocation = (Button) findViewById(R.id.deleteLocation);
// Loading products in Background Thread
new LoadAllLocation().execute();
deleteLocation.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
new DeleteLocation().execute();
}
});
// Get listview
ListView lo = getListView();
getListAdapter().getCount();
locationCount.setText(getListAdapter().getCount());
}
/*****************************************************************
* Background Async Task to Delete Product
* */
class DeleteLocation extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(ViewAllLocations.this);
pDialog.setMessage("Deleting Location...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
/**
* Deleting product
* */
protected String doInBackground(String... args) {
// Check for success tag
int success;
try {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("id", id));
// getting product details by making HTTP request
JSONObject json = jsonParser.makeHttpRequest(
url_delete_profile, "POST", params);
// check your log for json response
Log.d("Delete Product", json.toString());
// json success tag
success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// product successfully deleted
// notify previous activity by sending code 100
// Intent i = getIntent();
// send result code 100 to notify about product deletion
//setResult(100, i);
Toast.makeText(getApplicationContext(), "Location Deleted",
Toast.LENGTH_SHORT).show();
finish();
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog once product deleted
pDialog.dismiss();
}
}
/**
* Background Async Task to Load all product by making HTTP Request
* */
class LoadAllLocation extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(ViewAllLocations.this);
pDialog.setMessage("Loading Locations. Please wait...");
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>();
// getting JSON string from URL
JSONObject json = jsonParser.makeHttpRequest(url_all_profile, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Profiles: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
userprofile = json.getJSONArray(TAG_LOCATION);
// looping through All Products
for (int i = 0; i < userprofile.length(); i++) {
JSONObject c = userprofile.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_ID);
String latitude = c.getString(TAG_LATITUDE);
String longitude = c.getString(TAG_LONGITUDE);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_ID, id);
map.put(TAG_LATITUDE, latitude);
map.put(TAG_LONGITUDE, longitude);
// adding HashList to ArrayList
profileList.add(map);
}
} else {
// no products found
// Launch Add New product Activity
Intent i = new Intent(getApplicationContext(),
UserLocation.class);
// Closing all previous activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
ViewAllLocations.this, profileList,
R.layout.locationitem, new String[] { TAG_ID,
TAG_LATITUDE, TAG_LONGITUDE},
new int[] { R.id.id, R.id.latitude, R.id.longitude});
// updating listview
setListAdapter(adapter);
}
});
}
}
记录：＆＃34;它获取配置文件，然后当它到达最终结束时崩溃＆＃34;
04-19 19:09:48.665 26876-27452/com.example.ankhit.saveme D/All Profiles:﹕ {"success":1,"Location":[{"id":"26","longitude":"-0.5509257","latitude":"51.4276462"},{"id":"27","longitude":"-0.5509387","latitude":"51.4277023"},{"id":"28","longitude":"-0.5509387","latitude":"51.4277023"},{"id":"29","longitude":"-0.550991","latitude":"51.4275759"}]}
04-19 19:09:48.675 26876-26876/com.example.ankhit.saveme D/AndroidRuntime﹕ Shutting down VM
04-19 19:09:48.675 26876-26876/com.example.ankhit.saveme W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x42008ac8)
04-19 19:09:48.675 26876-26876/com.example.ankhit.saveme E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.ankhit.saveme.ViewAllLocations$LoadAllLocation$1.run(ViewAllLocations.java:260)
at android.app.Activity.runOnUiThread(Activity.java:4843)
at com.example.ankhit.saveme.ViewAllLocations$LoadAllLocation.onPostExecute(ViewAllLocations.java:246)
at com.example.ankhit.saveme.ViewAllLocations$LoadAllLocation.onPostExecute(ViewAllLocations.java:165)
at android.os.AsyncTask.finish(AsyncTask.java:631)
at android.os.AsyncTask.access$600(AsyncTask.java:177)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:176)
at android.app.ActivityThread.main(ActivityThread.java:5299)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
覆盖适配器中的get count（）方法或在此处发布，我会给你一些代码。
无论何时添加或删除项目，都要调用adapter.get count（）。