为什么CameraUpdateFactory类在我的项目中不起作用? 如果应用程序执行以下命令,则会崩溃: CameraUpdate pino = CameraUpdateFactory.newLatLng(new LatLng(location.getLatitude(),location.getLongitude())); 如果我删除该行(当然还有下一行),代码将成功启动并显示地图。 我需要mapView,我需要使用新的api v2。 我以这种方式在布局中声明了mapView:
<com.google.android.gms.maps.MapView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:map="http://schemas.android.com/apk/res-auto"
android:id="@+id/mappa"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_below="@+id/buttonBar"
map:uiZoomControls="false"
/>
然后在mainActivity.java中我写了这个:
public class MainActivity extends FragmentActivity implements LocationListener, LocationSource {
public static boolean locatingMe=true;
public GoogleMap mappa;
public MapView mapView;
private OnLocationChangedListener onLocationChangedListener;
private LocationManager locationManager;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mapView = (MapView) findViewById(R.id.mappa);
mapView.onCreate(savedInstanceState);
locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
//You may want to pass a different provider in as the first arg here
//depending on the location accuracy that you desire
//see LocationManager.getBestProvider()
Criteria locationCriteria = new Criteria();
locationCriteria.setAccuracy(Criteria.NO_REQUIREMENT);
locationManager.requestLocationUpdates(locationManager.getBestProvider(locationCriteria, true), 1L, 2F, this);
if (mappa == null) {
mappa=mapView.getMap();
//This is how you register the LocationSource
mappa.setLocationSource(this);
mappa.getUiSettings().setMyLocationButtonEnabled(false);
mappa.setMyLocationEnabled(true);
}
}
@Override
public void onPause()
{
if(locationManager != null)
{
locationManager.removeUpdates(this);
}
mapView.onPause();
super.onPause();
}
@Override
public void onResume()
{
checkGooglePlayServicesAvailability();
checkGps();
mapView.onResume();
super.onResume();
}
@Override
protected void onDestroy() {
mapView.onDestroy();
super.onDestroy();
}
@Override
public void onLowMemory() {
super.onLowMemory();
mapView.onLowMemory();
}
@Override
public void activate(OnLocationChangedListener listener)
{
onLocationChangedListener = listener;
}
@Override
public void deactivate()
{
onLocationChangedListener = null;
}
@Override
public void onLocationChanged(Location location)
{
if( onLocationChangedListener != null )
{
onLocationChangedListener.onLocationChanged( location );
//Move the camera to the user's location once it's available!
//only if locatingMe is true
if (locatingMe) {
if (mappa!=null){
CameraUpdate pino= CameraUpdateFactory.newLatLng(new LatLng(location.getLatitude(), location.getLongitude()));
mappa.animateCamera(pino);
}
}
}
}
@Override
public void onProviderDisabled(String provider)
{
// TODO Auto-generated method stub
Toast.makeText(this, "provider disabled", Toast.LENGTH_SHORT).show();
}
@Override
public void onProviderEnabled(String provider)
{
// TODO Auto-generated method stub
Toast.makeText(this, "provider enabled", Toast.LENGTH_SHORT).show();
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras)
{
// TODO Auto-generated method stub
Toast.makeText(this, "status changed", Toast.LENGTH_SHORT).show();
}
LogCat中的错误如下:
Caused by: java.lang.NullPointerException: CameraUpdateFactory is not initialized.
答案 0 :(得分:56)
我通过在“onCreate”上添加以下行来解决问题:
try {
MapsInitializer.initialize(this);
} catch (GooglePlayServicesNotAvailableException e) {
e.printStackTrace();
}
原因是需要启动CameraUpdateFactory(即使从文档中看起来似乎使用mapview它也应该自动初始化)
我甚至用“公共类MainActivity extends Activity”替换了“公共类MainActivity扩展FragmentActivity”。但我认为最后这件事并不需要......
答案 1 :(得分:2)
如果我使用:
try {
MapsInitializer.initialize(this);
} catch (GooglePlayServicesNotAvailableException e) {
e.printStackTrace();
}
异常给我这个错误:
Unreachable catch block for GooglePlayServicesNotAvailableException.
这个异常永远不会从try语句体&#34;。
中抛出我只使用:
MapsInitializer.initialize(this);
:)