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我的getLastKnownLocation打開了「null」。我可以獲取我放入的位置以顯示用戶位置一直在嘗試的位置。從文檔中，在這裏以及4 05個教程中，我認爲我做得對，但是......我不是。我似乎無法弄清楚爲什麼。Android的地圖位置返回null
如果有人有一秒鐘來看看這將是偉大的。
package com.kita.Maps;
import java.util.ArrayList;
import java.util.List;
import com.google.android.maps.GeoPoint;
import com.google.android.maps.ItemizedOverlay;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapView;
import com.google.android.maps.MyLocationOverlay;
import com.google.android.maps.Overlay;
import com.google.android.maps.OverlayItem;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.net.MailTo;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.Toast;
public class MapsActivity extends MapActivity implements LocationListener{
/** Called when the activity is first created. */
MapView map;
private MyLocationOverlay me = null;
Drawable d;
List<Overlay> overlayList;
LocationManager lm;
String towers;
int lat;
int longi;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
map = (MapView) findViewById(R.id.myMain);
map.setBuiltInZoomControls(true);
Touchy t = new Touchy();
overlayList = map.getOverlays();
overlayList.add(t);
map.getController().setCenter(
getPoint(40.76793169992044, -73.98180484771729));
map.getController().setZoom(17);
map.setBuiltInZoomControls(true);
Drawable marker = getResources().getDrawable(R.drawable.pin_yellow);
marker.setBounds(0, 0, marker.getIntrinsicWidth(),
marker.getIntrinsicHeight());
map.getOverlays().add(new SitesOverlay(marker));
me = new MyLocationOverlay(this, map);
map.getOverlays().add(me);
d = getResources().getDrawable(R.drawable.pin_blue);
// Geo Location of phone
lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Criteria crit = new Criteria();
towers = lm.getBestProvider(crit, false);
Location location = lm.getLastKnownLocation(towers);
if(location != null){
lat = (int) (location.getLatitude()*1E6);
longi = (int) (location.getLongitude()*1E6);
GeoPoint ourLocation = new GeoPoint(lat, longi);
OverlayItem overlayItem = new OverlayItem(ourLocation, "Quit hitting your self","");
CustomPinpoint custom = new CustomPinpoint(d, MapsActivity.this);
custom.insertPinpoint(overlayItem);
overlayList.add(custom);
}
else{
Toast.makeText(MapsActivity.this, "Couldn't get provider", Toast.LENGTH_SHORT).show();
}
}
@Override
public void onResume() {
super.onResume();
me.enableCompass();
lm.requestLocationUpdates(towers, 500, 1, this);
}
@Override
public void onPause() {
super.onPause();
me.disableCompass();
lm.removeUpdates(this);
}
@Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}
class Touchy extends Overlay {
public boolean onTouchEvent(MotionEvent e, MapView m) {
return false;
}
}
private GeoPoint getPoint(double lat, double lon) {
return (new GeoPoint((int) (lat * 1000000.0), (int) (lon * 1000000.0)));
}
private class SitesOverlay extends ItemizedOverlay<OverlayItem> {
private List<OverlayItem> items = new ArrayList<OverlayItem>();
public SitesOverlay(Drawable marker) {
super(marker);
boundCenterBottom(marker);
items.add(new OverlayItem(getPoint(40.748963847316034,
-73.96807193756104), "UN", "United Nations"));
items.add(new OverlayItem(getPoint(40.76866299974387,
-73.98268461227417), "Lincoln Center",
"Home of Jazz at Lincoln Center"));
items.add(new OverlayItem(getPoint(40.765136435316755,
-73.97989511489868), "Carnegie Hall",
"Where you go with practice, practice, practice"));
items.add(new OverlayItem(getPoint(40.70686417491799,
-74.01572942733765), "The Downtown Club",
"Original home of the Heisman Trophy"));
populate();
}
@Override
protected OverlayItem createItem(int i) {
return (items.get(i));
}
@Override
protected boolean onTap(int i) {
Toast.makeText(MapsActivity.this, items.get(i).getSnippet(),
Toast.LENGTH_SHORT).show();
return (true);
}
@Override
public int size() {
return (items.size());
}
}
public void onLocationChanged(Location l) {
// TODO Auto-generated method stub
lat = (int) (l.getLatitude() *1E6);
longi = (int) (l.getLongitude()*1E6);
GeoPoint ourLocation = new GeoPoint(lat, longi);
OverlayItem overlayItem = new OverlayItem(ourLocation, "Quit hitting your self","");
CustomPinpoint custom = new CustomPinpoint(d, MapsActivity.this);
custom.insertPinpoint(overlayItem);
overlayList.add(custom);
}
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
}
這裏是我的自定義指針類：
package com.kita.Maps;
import java.util.ArrayList;
import android.content.Context;
import android.graphics.drawable.Drawable;
import com.google.android.maps.ItemizedOverlay;
import com.google.android.maps.OverlayItem;
public class CustomPinpoint extends ItemizedOverlay<OverlayItem>{
private ArrayList<OverlayItem> pinpoints = new ArrayList<OverlayItem>();
private Context c;
public CustomPinpoint(Drawable defaultMarker) {
super(boundCenter(defaultMarker));
// TODO Auto-generated constructor stub
}
public CustomPinpoint(Drawable m, Context context) {
// TODO Auto-generated constructor stub
this(m);
c = context;
}
@Override
protected OverlayItem createItem(int i) {
// TODO Auto-generated method stub
return pinpoints.get(i);
}
@Override
public int size() {
// TODO Auto-generated method stub
return pinpoints.size();
}
public void insertPinpoint(OverlayItem item){
pinpoints.add(item);
this.populate();
}
}
這是正確的答案。我把這張支票交給了Ben，因爲提到「requestLocationUpdates」讓我對我的整個應用程序提供了最好的答案。謝謝 – Rick 2011-12-23 19:38:50