我正在尝试谷歌从谷歌api放置数据并显示在列表视图中。我成功获取数据并设置为适配器，但无法在listview中显示。
MainActivity。 java
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv=(ListView)findViewById(R.id.listView);
StringBuilder sbValue = new StringBuilder(sbMethod());
PlacesTask placesTask = new PlacesTask();
placesTask.execute(sbValue.toString());
MyAdapter adapter=new MyAdapter(MainActivity.this,R.layout.my_adapter_item,arr);
lv.setAdapter(adapter);
}
public StringBuilder sbMethod() {
//use your current location here
double mLatitude =-33.8670522;
double mLongitude =151.1957362;
StringBuilder sb = new StringBuilder("https://maps.googleapis.com/maps/api/place/nearbysearch/json?");
sb.append("location=" + mLatitude + "," + mLongitude);
sb.append("&radius=5000");
sb.append("&types=" + "restaurant");
sb.append("&sensor=true");
sb.append("&key=AIzaSyC2SaN5I5u2eWw3zr4OZoLwD0qvCU-_uUw");
Log.d("Map", "api: " + sb.toString());
return sb;
}
private class PlacesTask extends AsyncTask<String, Integer, String> {
String data = null;
// Invoked by execute() method of this object
@Override
protected String doInBackground(String... url) {
try {
data = downloadUrl(url[0]);
} catch (Exception e) {
Log.d("Background Task", e.toString());
}
return data;
}
// Executed after the complete execution of doInBackground() method
@Override
protected void onPostExecute(String result) {
ParserTask parserTask = new ParserTask();
// Start parsing the Google places in JSON format
// Invokes the "doInBackground()" method of the class ParserTask
parserTask.execute(result);
}
}
private String downloadUrl(String strUrl) throws IOException {
String data = "";
InputStream iStream = null;
HttpURLConnection urlConnection = null;
try {
URL url = new URL(strUrl);
// Creating an http connection to communicate with url
urlConnection = (HttpURLConnection) url.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream));
StringBuffer sb = new StringBuffer();
String line = "";
while ((line = br.readLine()) != null) {
sb.append(line);
}
data = sb.toString();
br.close();
} catch (Exception e) {
Log.d("Exception downloading", e.toString());
} finally {
iStream.close();
urlConnection.disconnect();
}
return data;
}
private class ParserTask extends AsyncTask<String, Integer, List<HashMap<String, String>>> {
JSONObject jObject;
// Invoked by execute() method of this object
@Override
protected List<HashMap<String, String>> doInBackground(String... jsonData) {
List<HashMap<String, String>> places = null;
Place_JSON placeJson = new Place_JSON();
try {
jObject = new JSONObject(jsonData[0]);
places = placeJson.parse(jObject);
} catch (Exception e) {
Log.d("Exception", e.toString());
}
return places;
}
// Executed after the complete execution of doInBackground() method
@Override
protected void onPostExecute(List<HashMap<String, String>> list) {
for (int i = 0; i < list.size(); i++) {
HashMap<String, String> hmPlace = list.get(i);
double lat = Double.parseDouble(hmPlace.get("lat"));
double lng = Double.parseDouble(hmPlace.get("lng"));
}
}
}
public class Place_JSON {
/**
* Receives a JSONObject and returns a list
*/
public List<HashMap<String, String>> parse(JSONObject jObject) {
JSONArray jPlaces = null;
try {
/** Retrieves all the elements in the 'places' array */
jPlaces = jObject.getJSONArray("results");
} catch (JSONException e) {
e.printStackTrace();
}
/** Invoking getPlaces with the array of json object
* where each json object represent a place
*/
return getPlaces(jPlaces);
}
private List<HashMap<String, String>> getPlaces(JSONArray jPlaces) {
int placesCount = jPlaces.length();
List<HashMap<String, String>> placesList = new ArrayList<HashMap<String, String>>();
HashMap<String, String> place = null;
/** Taking each place, parses and adds to list object */
for (int i = 0; i < placesCount; i++) {
try {
/** Call getPlace with place JSON object to parse the place */
place = getPlace((JSONObject) jPlaces.get(i));
placesList.add(place);
} catch (JSONException e) {
e.printStackTrace();
}
}
return placesList;
}
/**
* Parsing the Place JSON object
*/
private HashMap<String, String> getPlace(JSONObject jPlace) {
HashMap<String, String> place = new HashMap<String, String>();
String placeName = "-NA-";
String vicinity = "-NA-";
String latitude = "";
String longitude = "";
String reference = "";
try {
// Extracting Place name, if available
if (!jPlace.isNull("name")) {
placeName = jPlace.getString("name");
}
// Extracting Place Vicinity, if available
if (!jPlace.isNull("vicinity")) {
vicinity = jPlace.getString("vicinity");
}
latitude = jPlace.getJSONObject("geometry").getJSONObject("location").getString("lat");
longitude = jPlace.getJSONObject("geometry").getJSONObject("location").getString("lng");
reference = jPlace.getString("reference");
place.put("place_name", placeName);
place.put("vicinity", vicinity);
place.put("lat", latitude);
place.put("lng", longitude);
place.put("reference", reference);
map1=new HashMap<String, String>();
map1.put("Name",placeName);
map1.put("Vicinity",vicinity);
arr.add(map1);
Log.w("MainActivity",placeName+";"+vicinity);
} catch (JSONException e) {
e.printStackTrace();
}
return place;
}
}
这里我从HashMap<String, String> getPlace(JSONObject jPlace)获取数据并设置为适配器。
这个适配器我在Oncreate中设置为listview。
适配器类
public class MyAdapter extends BaseAdapter {
ArrayList<HashMap<String, String>> names;
int data;
Context ctxt;
LayoutInflater inflater;
public MyAdapter (Context c, int nes, ArrayList<HashMap<String, String>> enj){
this.ctxt = c;
this.data = nes;
this.names = enj;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return names.size();
}
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return names.get(arg0);
}
@Override
public long getItemId(int arg0) {
// TODO Auto-generated method stub
return arg0;
}
@Override
public View getView(int position, View convertView, ViewGroup viewGroup) {
// TODO Create the cell (View) and populate it with an element of the array
ViewHolder holder = new ViewHolder();
if (convertView == null) {
convertView = LayoutInflater.from(ctxt).inflate(data, viewGroup);
holder.nam = (TextView) convertView . findViewById (R.id.name);
holder.vic = (TextView) convertView . findViewById (R.id.vicinity);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView . getTag ();
}
holder.nam.setText(names.get(position).get("Name"));
holder.vic.setText(names.get(position).get("Vicinity"));
return convertView;
}
class ViewHolder {
TextView nam,vic;
}
}
这里我无法在listview中显示数据。请帮助我。
答案 0 :(得分：1)
一旦“arr”发生变化，我们需要通知适配器数据集已更改。在ParserTask的onPostExecute中，添加以下行
adapter.notifyDataSetChanged();
答案 1 :(得分：0)
尝试使用：
而不是
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return names.get(arg0);
}
使用
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return arg0;
}