下面的代码，当我取消注释＆＃39;列表等时它会崩溃，并在我添加叠加层时添加叠加层以列出它崩溃。我可以在＆＃39; oncreate中添加一个叠加图标，它不会崩溃，但会将其添加到＆＃39; onlocationchanged＆＃39;它崩溃了
public class MainActivity extends MapActivity implements LocationListener {
MyLocationOverlay myLocationOverlay;
public MapView mapView;
MapController mc;
OverlayItem overlayitem;
List<Overlay> mapOverlays;
HelloItemizedOverlay itemizedoverlay;
GeoPoint myLocationGeoPoint;
private MockGpsProvider mMockGpsProviderTask = null;
//mMockGpsProviderTask = new MockGpsProvider();
/* This method is called when use position will get changed */
public void onLocationChanged(Location location) {
GeoPoint myLocationGeoPoint = new GeoPoint((int)(location.getLatitude() * 1e6) , (int)(location.getLongitude() * 1e6));
// Toast.makeText(this, "changinglocation", Toast.LENGTH_SHORT).show();
String message = String.format(
"New Location \n Longitude: %1$s \n Latitude: %2$s",
(int)(location.getLongitude()), (int)(location.getLatitude())
);
Toast.makeText(this, message, Toast.LENGTH_LONG).show();
// mc.setCenter(myLocationGeoPoint);
mc.animateTo(myLocationGeoPoint);
// mc.setZoom(11);
//}
// mapOverlays = mapView.getOverlays();
// Drawable drawable = this.getResources().getDrawable(R.drawable.androidmarker);
overlayitem = new OverlayItem(myLocationGeoPoint, "Hola, Mundo!", "I'm in Mexico City!");
itemizedoverlay.addOverlay(overlayitem);
mapOverlays.add(itemizedoverlay);
}
public void onProviderDisabled(String provider) {
Toast.makeText(this, "No mock data mofo", Toast.LENGTH_SHORT).show();
}
public void onProviderEnabled(String provider) {
}
public void onStatusChanged(String provider, int status, Bundle extras) {
}
int test()
{
int i1=getIntent().getIntExtra("key", -1);
return(i1);
}
@Override
protected boolean isRouteDisplayed() {
return false;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MapView mapView = (MapView) findViewById(R.id.mapview);
mc = mapView.getController();
mapView.setBuiltInZoomControls(true);
mapView.setSatellite(true);
mc.setZoom(19);
List<Overlay> mapOverlays = mapView.getOverlays();
Drawable drawable = this.getResources().getDrawable(R.drawable.androidmarker);
HelloItemizedOverlay itemizedoverlay = new HelloItemizedOverlay(drawable, this);
GeoPoint point = new GeoPoint(19240000,-99120000);
//GeoPoint point = new GeoPoint(19240000,test());
//GeoPoint point = new GeoPoint(19240000,message);
OverlayItem overlayitem = new OverlayItem(point, "Hola, Mundo!", "I'm in Mexico City!");
itemizedoverlay.addOverlay(overlayitem);
mapOverlays.add(itemizedoverlay);
// LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
// Criteria criteria = new Criteria();
// criteria.setAccuracy( Criteria.ACCURACY_COARSE );
// String provider = lm.getBestProvider( criteria, true );
// if ( provider == null ) {
// Toast.makeText(this, "No mock data mofo", Toast.LENGTH_SHORT).show();
// }
/** Setup GPS. */
LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
if(locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)){
/// use real GPS provider if enabled on the device
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
}
else if(!locationManager.isProviderEnabled(MockGpsProvider.GPS_MOCK_PROVIDER)) {
// otherwise enable the mock GPS provider
locationManager.addTestProvider(MockGpsProvider.GPS_MOCK_PROVIDER, false, false,
false, false, true, false, false, 0, 5);
locationManager.setTestProviderEnabled(MockGpsProvider.GPS_MOCK_PROVIDER, true);
Toast.makeText(this, "mock data enabled mofo", Toast.LENGTH_SHORT).show();
}
if(locationManager.isProviderEnabled(MockGpsProvider.GPS_MOCK_PROVIDER)) {
locationManager.requestLocationUpdates(MockGpsProvider.GPS_MOCK_PROVIDER, 0, 0, this);
/** Load mock GPS data from file and create mock GPS provider. */
try {
// create a list of Strings that can dynamically grow
List<String> data = new ArrayList<String>();
/** read a CSV file containing WGS84 coordinates from the 'assets' folder
* (The website http://www.gpsies.com offers downloadable tracks. Select
* a track and download it as a CSV file. Then add it to your assets folder.)
*/
InputStream is = getAssets().open("mock_gps_data.csv");
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
// add each line in the file to the list
String line = null;
while ((line = reader.readLine()) != null) {
data.add(line);
}
// convert to a simple array so we can pass it to the AsyncTask
String[] coordinates = new String[data.size()];
data.toArray(coordinates);
// create new AsyncTask and pass the list of GPS coordinates
mMockGpsProviderTask = new MockGpsProvider();
mMockGpsProviderTask.execute(coordinates);
}
catch (Exception e) {}
}
}
private class MockGpsProvider extends AsyncTask<String, Integer, Void> {
public static final String LOG_TAG = "GpsMockProvider";
public static final String GPS_MOCK_PROVIDER = "GpsMockProvider";
/** Keeps track of the currently processed coordinate. */
public Integer index = 0;
@Override
protected Void doInBackground(String... data) {
// process data
for (String str : data) {
// skip data if needed (see the Activity's savedInstanceState functionality)
if(index < 5) {
index++;
continue;
}
// let UI Thread know which coordinate we are processing
publishProgress(index);
// retrieve data from the current line of text
Double latitude = null;
Double longitude = null;
Double altitude= null;
try {
String[] parts = str.split(",");
latitude = Double.valueOf(parts[0]);
longitude = Double.valueOf(parts[1]);
altitude = Double.valueOf(parts[2]);
}
catch(NullPointerException e) { break; } // no data available
catch(Exception e) { continue; } // empty or invalid line
// translate to actual GPS location
Location location = new Location(GPS_MOCK_PROVIDER);
location.setLatitude(latitude);
location.setLongitude(longitude);
location.setAltitude(altitude);
location.setTime(System.currentTimeMillis());
// show debug message in log
Log.d(LOG_TAG, location.toString());
// provide the new location
LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
locationManager.setTestProviderLocation(GPS_MOCK_PROVIDER, location);
// sleep for a while before providing next location
try {
Thread.sleep(200);
// gracefully handle Thread interruption (important!)
if(Thread.currentThread().isInterrupted())
throw new InterruptedException("");
} catch (InterruptedException e) {
break;
}
// keep track of processed locations
index++;
}
return null;
}
@Override
protected void onProgressUpdate(Integer... values) {
Log.d(LOG_TAG, "onProgressUpdate():"+values[0]);
mMockGpsProviderIndex = values[0];
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
答案 0 :(得分：1)
您可以将onLocationChanged()中使用的所有变量声明为全局变量，以避免重新分配内存和错误，它在onCreate()方法中工作的原因是它仅在{{1}时执行一次每当位置发生变化时，都会执行几次。
修改
您未在onLocationChanged()方法中添加任何位置更新请求。请参阅此link以了解获取位置更新的最佳策略。
答案 1 :(得分：0)
您没有初始化mapView变量。在onCreate方法中，您正在初始化LOCAL变量：
MapView mapView = (MapView) findViewById(R.id.mapview);
不是全球mapView !!!