嘿，我是Android的新手，想知道是否有人可以帮助我。我有一个MapsActivity，当导航到它时会崩溃。我认为我已经缩小到了查看错误的确切位置，但我无法弄清楚要改变什么。
我在下面添加了整个MapsActivity类。问题出现在此行mLocationManager.requestLocationUpdates(provider, 5000, 0, this);
上的onConnected方法中。 Android Studio建议我投射这个＆＃39;到LocationListener，但这不起作用，我这样做的错误列在MapsActivity代码下面。
我也尝试输入mLocationListener代替＆＃39;这个＆＃39;但是没有用，我也得到了下面列出的错误。
任何帮助都非常受欢迎。谢谢！
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback, GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, com.google.android.gms.location.LocationListener {
private static final int MY_PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION = 1;
private static final int MY_PERMISSIONS_REQUEST_ACCESS_COARSE_LOCATION = 2;
private GoogleMap mMap;
private GoogleApiClient mGoogleApiClient;
private LocationManager mLocationManager;
private Location mLastLocation;
private LocationListener mLocationListener;
private String mLatitude;
private String mLongitude;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
// Create an instance of GoogleAPIClient.
if (mGoogleApiClient == null) {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
}
//create instance of location manager and get location service
mLocationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
}
/**
* Manipulates the map once available.
* This callback is triggered when the map is ready to be used.
* This is where we can add markers or lines, add listeners or move the camera. In this case,
* we just add a marker near Sydney, Australia.
* If Google Play services is not installed on the device, the user will be prompted to install
* it inside the SupportMapFragment. This method will only be triggered once the user has
* installed Google Play services and returned to the app.
*/
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
// Add a marker in Sydney and move the camera
LatLng sydney = new LatLng(-34, 151);
mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
}
@Override
protected void onStart() {
mGoogleApiClient.connect();
super.onStart();
}
@Override
protected void onStop() {
mGoogleApiClient.disconnect();
//mLocationManager.removeUpdates((LocationManager) this);
super.onStop();
}
@Override
public void onConnected(@Nullable Bundle bundle) {
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setAltitudeRequired(true);
criteria.setBearingRequired(true);
criteria.setCostAllowed(true);
criteria.setPowerRequirement(Criteria.POWER_LOW);
String provider = mLocationManager.getBestProvider(criteria, true);
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
mLocationManager.requestLocationUpdates(provider, 5000, 0, this);
mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
if(mLastLocation != null){
mLatitude = String.valueOf(mLastLocation.getLatitude());
mLongitude = String.valueOf(mLastLocation.getLongitude());
Toast.makeText(this, mLatitude + " , " + mLongitude, Toast.LENGTH_SHORT).show();
}
} else {
Toast.makeText(this, "Permission denied, please accept permission..", Toast.LENGTH_SHORT).show();
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION);
}
}
@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults){
switch (requestCode){
case MY_PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION:{
//if request cancelled the results array is empty
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
//do task you wish to do
//Intent intent = (new Intent(this, MapsActivity.class));
//startActivity(intent);
}else{
//permission denied, disable functionality(GPS)
}
return;
}
//other cases go here
}
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
}
@Override
public void onLocationChanged(Location location) {
}
}
投射错误 -
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.a8460p.locationotes, PID: 23305
java.lang.ClassCastException: com.example.a8460p.locationotes.MapsActivity cannot be cast to android.location.LocationListener
at com.example.a8460p.locationotes.MapsActivity.onConnected(MapsActivity.java:106)
at com.google.android.gms.common.internal.zzm.zzq(Unknown Source)
at com.google.android.gms.internal.zzaal.zzo(Unknown Source)
at com.google.android.gms.internal.zzaaj.zzvE(Unknown Source)
at com.google.android.gms.internal.zzaaj.onConnected(Unknown Source)
at com.google.android.gms.internal.zzaan.onConnected(Unknown Source)
at com.google.android.gms.internal.zzzy.onConnected(Unknown Source)
at com.google.android.gms.common.internal.zzl$1.onConnected(Unknown Source)
at com.google.android.gms.common.internal.zzf$zzj.zzwZ(Unknown Source)
at com.google.android.gms.common.internal.zzf$zza.zzc(Unknown Source)
at com.google.android.gms.common.internal.zzf$zza.zzu(Unknown Source)
at com.google.android.gms.common.internal.zzf$zze.zzxa(Unknown Source)
at com.google.android.gms.common.internal.zzf$zzd.handleMessage(Unknown Source)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:234)
at android.app.ActivityThread.main(ActivityThread.java:5526)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
更换＆＃39;这个＆＃39;与mLocationListener错误 -
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.a8460p.locationotes, PID: 24073
java.lang.IllegalArgumentException: invalid listener: null
at android.location.LocationManager.checkListener(LocationManager.java:1733)
at android.location.LocationManager.requestLocationUpdates(LocationManager.java:461)
at com.example.a8460p.locationotes.MapsActivity.onConnected(MapsActivity.java:106)
at com.google.android.gms.common.internal.zzm.zzq(Unknown Source)
at com.google.android.gms.internal.zzaal.zzo(Unknown Source)
at com.google.android.gms.internal.zzaaj.zzvE(Unknown Source)
at com.google.android.gms.internal.zzaaj.onConnected(Unknown Source)
at com.google.android.gms.internal.zzaan.onConnected(Unknown Source)
at com.google.android.gms.internal.zzzy.onConnected(Unknown Source)
at com.google.android.gms.common.internal.zzl$1.onConnected(Unknown Source)
at com.google.android.gms.common.internal.zzf$zzj.zzwZ(Unknown Source)
at com.google.android.gms.common.internal.zzf$zza.zzc(Unknown Source)
at com.google.android.gms.common.internal.zzf$zza.zzu(Unknown Source)
at com.google.android.gms.common.internal.zzf$zze.zzxa(Unknown Source)
at com.google.android.gms.common.internal.zzf$zzd.handleMessage(Unknown Source)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:234)
at android.app.ActivityThread.main(ActivityThread.java:5526)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
答案 0 :(得分：1)
让MapsActivity实施android.location.LocationListener而不是com.google.android.gms.location.LocationListener
答案 1 :(得分：0)
您的requestLocationUpdates找不到监听器的实例，因此将MapsActivity.this添加到requestLocationUpdates
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
mLocationManager.requestLocationUpdates(provider, 5000, 0, MapsActivity.this);//Changed here
mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
if(mLastLocation != null){
mLatitude = String.valueOf(mLastLocation.getLatitude());
mLongitude = String.valueOf(mLastLocation.getLongitude());
Toast.makeText(this, mLatitude + " , " + mLongitude, Toast.LENGTH_SHORT).show();
}
} else {
Toast.makeText(this, "Permission denied, please accept permission..", Toast.LENGTH_SHORT).show();
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION);
}
答案 2 :(得分：0)
对于第一次崩溃：由于您对Activity实施的位置侦听器类的导入不正确而导致此崩溃。
使用com.google.android.gms.location.LocationListener
android.location.LocationListener
并且对于第二次崩溃使用下面的LocationListener，由于您对位置侦听器对象的空引用而发生此崩溃。
private LocationListener mLocationListener = new LocationListener() {
@Override
public void onLocationChanged(Location location) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
};