我试图通过从 Telnet 传递值来获得经纬度位置。完成之后，现在我尝试实施反向地理编码以获取模拟器中的 apporx 地址。 关注了这个链接
但它显示应用程序流意外停止。
日志猫错误..
05-19 16:51:14.292: E/AndroidRuntime(460): java.lang.NullPointerException
05-19 16:51:14.292: E/AndroidRuntime(460): at com.gps.HelloAndroidGpsActivity$ReverseGeocodeLookupTask.onPostExecute(HelloAndroidGpsActivity.java:137)
05-19 16:51:14.292: E/AndroidRuntime(460): at com.gps.HelloAndroidGpsActivity$ReverseGeocodeLookupTask.onPostExecute(HelloAndroidGpsActivity.java:1)
05-19 16:51:14.292: E/AndroidRuntime(460): at android.os.AsyncTask.finish(AsyncTask.java:417)
05-19 16:51:14.292: E/AndroidRuntime(460): at android.os.AsyncTask.access$300(AsyncTask.java:127)
05-19 16:51:14.292: E/AndroidRuntime(460): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
05-19 16:51:14.292: E/AndroidRuntime(460): at android.os.Handler.dispatchMessage(Handler.java:99)
05-19 16:51:14.292: E/AndroidRuntime(460): at android.os.Looper.loop(Looper.java:130)
05-19 16:51:14.292: E/AndroidRuntime(460): at android.app.ActivityThread.main(ActivityThread.java:3683)
05-19 16:51:14.292: E/AndroidRuntime(460): at java.lang.reflect.Method.invokeNative(Native Method)
05-19 16:51:14.292: E/AndroidRuntime(460): at java.lang.reflect.Method.invoke(Method.java:507)
05-19 16:51:14.292: E/AndroidRuntime(460): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-19 16:51:14.292: E/AndroidRuntime(460): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-19 16:51:14.292: E/AndroidRuntime(460): at dalvik.system.NativeStart.main(Native Method)
...
HelloAndroidGpsActivity.java
package com.gps;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
import com.gps.GeoCodeResult;
import com.gps.GeoCoder;
public class HelloAndroidGpsActivity extends Activity {
private static final long MINIMUM_DISTANCE_CHANGE_FOR_UPDATES = 1; // in Meters
private static final long MINIMUM_TIME_BETWEEN_UPDATES = 1000; // in Milliseconds
private GeoCoder geoCoder = new GeoCoder();
protected LocationManager locationManager;
protected Location currentLocation;
protected Button retrieveLocationButton;
protected Button reverseGeocodingButton;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
retrieveLocationButton = (Button) findViewById(R.id.retrieve_location_button);
reverseGeocodingButton = (Button) findViewById(R.id.reverse_geocoding_button);
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MINIMUM_TIME_BETWEEN_UPDATES,
MINIMUM_DISTANCE_CHANGE_FOR_UPDATES,
new MyLocationListener()
);
retrieveLocationButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
showCurrentLocation();
}
});
reverseGeocodingButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
performReverseGeocodingInBackground();
}
});
}
protected void performReverseGeocodingInBackground() {
showCurrentLocation();
new ReverseGeocodeLookupTask().execute((Void[])null);
}
protected void showCurrentLocation() {
currentLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (currentLocation != null) {
String message = String.format(
"Current Location \n Longitude: %1$s \n Latitude: %2$s",
currentLocation.getLongitude(), currentLocation.getLatitude()
);
Toast.makeText(HelloAndroidGpsActivity.this, message,
Toast.LENGTH_LONG).show();
}
}
private class MyLocationListener implements LocationListener {
public void onLocationChanged(Location location) {
String message = String.format(
"New Location \n Longitude: %1$s \n Latitude: %2$s",
location.getLongitude(), location.getLatitude()
);
Toast.makeText(HelloAndroidGpsActivity.this, message, Toast.LENGTH_LONG).show();
}
public void onStatusChanged(String s, int i, Bundle b) {
Toast.makeText(HelloAndroidGpsActivity.this, "Provider status changed",
Toast.LENGTH_LONG).show();
}
public void onProviderDisabled(String s) {
Toast.makeText(HelloAndroidGpsActivity.this,
"Provider disabled by the user. GPS turned off",
Toast.LENGTH_LONG).show();
}
public void onProviderEnabled(String s) {
Toast.makeText(HelloAndroidGpsActivity.this,
"Provider enabled by the user. GPS turned on",
Toast.LENGTH_LONG).show();
}
}
public class ReverseGeocodeLookupTask extends AsyncTask <Void, Void, GeoCodeResult> {
private ProgressDialog progressDialog;
@Override
protected void onPreExecute() {
this.progressDialog = ProgressDialog.show(
HelloAndroidGpsActivity.this,
"Please wait...contacting Yahoo!", // title
"Requesting reverse geocode lookup", // message
true // indeterminate
);
}
@Override
protected GeoCodeResult doInBackground(Void... params) {
return geoCoder.reverseGeoCode(currentLocation.getLatitude(), currentLocation.getLongitude());
}
@Override
protected void onPostExecute(GeoCodeResult result) {
Toast.makeText(HelloAndroidGpsActivity.this, result.toString(), Toast.LENGTH_LONG).show();
}
}
}
地理编码器.java
*package com.gps;
import com.gps.GeoCodeResult;
import com.gps.HttpRetriever;
import com.gps.XmlParser;
public class GeoCoder {
private static final String YAHOO_API_BASE_URL = "http://where.yahooapis.com/geocode?q=%1$s,+%2$s&gflags=R&appid=[yourappidhere]"; **//This is correct API**
private HttpRetriever httpRetriever = new HttpRetriever();
private XmlParser xmlParser = new XmlParser();
public GeoCodeResult reverseGeoCode(double latitude, double longitude) {
String url = String.format(YAHOO_API_BASE_URL, String.valueOf(latitude), String.valueOf(longitude));
String response = httpRetriever.retrieve(url);
return xmlParser.parseXmlResponse(response);
}
}*
地理编码结果
package com.gps;
public class GeoCodeResult {
public String line1;
public String line2;
public String line3;
public String line4;
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("Location:");
if (line1!=null)
builder.append("-"+line1);
if (line2!=null)
builder.append("-"+line2);
if (line3!=null)
builder.append("-"+line3);
if (line4!=null)
builder.append("-"+line4);
return builder.toString();
}
}
问题是地理编码结果为空
我错过了什么吗？点我是我做错了。谢谢