我得到null jsonarray，使用官方android Facebook api示例代码Hackbook for user Check in and nearest places list。
public class Places extends Activity implements OnItemClickListener {
private Handler mHandler;
private JSONObject location;
protected ListView placesList;
private Facebook mFacebook;
protected LocationManager lm;
protected MyLocationListener locationListener;
private AsyncFacebookRunner mAsyncRunner;
protected static JSONArray jsonArray;
final static double TIMES_SQUARE_LAT = 40.756;
final static double TIMES_SQUARE_LON = -73.987;
protected ProgressDialog dialog;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mHandler = new Handler();
location = new JSONObject();
setContentView(R.layout.places_list);
mFacebook = new Facebook(Constants.FB_APP_ID);
mAsyncRunner = new AsyncFacebookRunner(mFacebook);
Bundle extras = getIntent().getExtras();
String default_or_new = extras.getString("LOCATION");
if (default_or_new.equals("times_square")) {
try {
location.put("latitude",new Double(TIMES_SQUARE_LAT) );
location.put("longitude",new Double(TIMES_SQUARE_LON));
} catch (JSONException e) {
}
fetchPlaces();
} else {
getLocation();
}
}
public void getLocation() {
/*
* launch a new Thread to get new location
*/
new Thread() {
@Override
public void run() {
Looper.prepare();
dialog = ProgressDialog.show(Places.this, "","Fetching Location", false, true,
new DialogInterface.OnCancelListener() {
@Override
public void onCancel(DialogInterface dialog) {
showToast("No location fetched.");
}
});
if (lm == null) {
lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
}
if (locationListener == null) {
locationListener = new MyLocationListener();
}
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_COARSE);
String provider = lm.getBestProvider(criteria, true);
if (provider != null && lm.isProviderEnabled(provider)) {
lm.requestLocationUpdates(provider, 1, 0, locationListener,
Looper.getMainLooper());
} else {
/*
* GPS not enabled, prompt user to enable GPS in the
* Location menu
*/
new AlertDialog.Builder(Places.this)
.setTitle("enable_gps_title")
.setMessage("enable_gps")
.setPositiveButton("GPS Settings",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
startActivityForResult(
new Intent(
android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS),
0);
}
})
.setNegativeButton(R.string.cancel,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
Places.this.finish();
}
}).show();
}
Looper.loop();
}
}.start();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
/*
* User returning from the Location settings menu. try to fetch location
* again.
*/
dialog.dismiss();
getLocation();
}
/*
* Fetch nearby places by providing the search type as 'place' within 1000
* mtrs of the provided lat & lon
*/
private void fetchPlaces() {
if (!isFinishing()) {
dialog = ProgressDialog.show(Places.this, "", "nearby_places", true,
true, new DialogInterface.OnCancelListener() {
@Override
public void onCancel(DialogInterface dialog) {
showToast("No places fetched.");
}
});
}
/*
* Source tag: fetch_places_tag
*/
Bundle params = new Bundle();
params.putString("type", "place");
try {
params.putString("center",
location.getString("latitude") + "," + location.getString("longitude"));
} catch (JSONException e) {
showToast("No places fetched.");
return;
}
params.putString("distance", "1000");
mAsyncRunner.request("search", params, new placesRequestListener());
}
/*
* Callback after places are fetched.
*/
public class placesRequestListener extends BaseRequestListener {
@Override
public void onComplete(final String response, final Object state) {
Log.d("Facebook-FbAPIs", "Got response: " + response);
dialog.dismiss();
try {
jsonArray = new JSONObject(response).getJSONArray("data");
if (jsonArray == null) {
showToast("Error: nearby places could not be fetched");
return;
}
} catch (JSONException e) {
showToast("Error: " + e.getMessage());
return;
}
mHandler.post(new Runnable() {
@Override
public void run() {
placesList = (ListView) findViewById(R.id.places_list);
placesList.setOnItemClickListener(Places.this);
placesList.setAdapter(new PlacesListAdapter(Places.this));
}
});
}
public void onFacebookError(FacebookError error) {
dialog.dismiss();
showToast("Fetch Places Error: " + error.getMessage());
}
}
@Override
public void onItemClick(AdapterView<?> arg0, View v, int position, long arg3) {
if (!mFacebook.isSessionValid()) {
Util.showAlert(this, "Warning", "You must first log in.");
} else {
try {
final String message = "Check-in from the " + getString(R.string.app_name);
final String name = jsonArray.getJSONObject(position).getString("name");
final String placeID = jsonArray.getJSONObject(position).getString("id");
new AlertDialog.Builder(this).setTitle("check_in_title")
.setMessage(String.format("check_in_at"))
.setPositiveButton("Chaeck in", new DialogInterface.OnClickListener() {
/*
* Source tag: check_in_tag Check-in user at the
* selected location posting to the me/checkins
* endpoint. More info here:
* https://developers.facebook
* .com/docs/reference/api/user/ - checkins
*/
@Override
public void onClick(DialogInterface dialog, int which) {
Bundle params = new Bundle();
params.putString("place", placeID);
params.putString("message", message);
params.putString("coordinates", location.toString());
mAsyncRunner.request("me/checkins", params, "POST",
new placesCheckInListener(), null);
}
}).setNegativeButton(R.string.cancel, null).show();
} catch (JSONException e) {
showToast("Error: " + e.getMessage());
}
}
}
public class placesCheckInListener extends BaseRequestListener {
@Override
public void onComplete(final String response, final Object state) {
showToast("API Response: " + response);
}
public void onFacebookError(FacebookError error) {
dialog.dismiss();
showToast("Check-in Error: " + error.getMessage());
}
}
public void showToast(final String msg) {
mHandler.post(new Runnable() {
@Override
public void run() {
Toast toast = Toast.makeText(Places.this, msg, Toast.LENGTH_LONG);
toast.show();
}
});
}
/**
* Definition of the list adapter
*/
public class PlacesListAdapter extends BaseAdapter {
private LayoutInflater mInflater;
Places placesList;
public PlacesListAdapter(Context context) {
mInflater = LayoutInflater.from(context);
}
@Override
public int getCount() {
return jsonArray.length();
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
JSONObject jsonObject = null;
try {
jsonObject = jsonArray.getJSONObject(position);
} catch (JSONException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
View hView = convertView;
if (convertView == null) {
hView = mInflater.inflate(R.layout.place_item, null);
ViewHolder holder = new ViewHolder();
holder.name = (TextView) hView.findViewById(R.id.place_name);
holder.location = (TextView) hView.findViewById(R.id.place_location);
hView.setTag(holder);
}
ViewHolder holder = (ViewHolder) hView.getTag();
try {
holder.name.setText(jsonObject.getString("name"));
} catch (JSONException e) {
holder.name.setText("");
}
try {
String location = jsonObject.getJSONObject("location").getString("street") + ", "
+ jsonObject.getJSONObject("location").getString("city") + ", "
+ jsonObject.getJSONObject("location").getString("state");
holder.location.setText(location);
} catch (JSONException e) {
holder.location.setText("");
}
return hView;
}
}
class ViewHolder {
TextView name;
TextView location;
}
class MyLocationListener implements LocationListener {
@Override
public void onLocationChanged(Location loc) {
dialog.dismiss();
if (loc != null) {
try {
location.put("latitude", new Double(loc.getLatitude()));
location.put("longitude", new Double(loc.getLongitude()));
} catch (JSONException e) {
}
showToast("Location acquired: " + String.valueOf(loc.getLatitude()) + " "
+ String.valueOf(loc.getLongitude()));
lm.removeUpdates(this);
fetchPlaces();
}
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
}
在下面的行中获取Jsonarray null：
jsonArray = new JSONObject（response）.getJSONArray（“data”）;
让我知道上面这段代码中有什么问题