位置出现 NullPointerException
NullPointerException in location
我的 Android 应用程序中的位置变量有问题。在此屏幕上 GPSLocation 工作正常，但是当我将屏幕更改为 gpsLocation.getLastKnownLocation() 时，此方法始终 returns null.
第一个屏幕：
public class MainActivity extends ActionBarActivity {
private TextView text;
private GPSLocation gpsLocation;
private Location targetLocation;
private EditText editLatitude;
private EditText editLongitude;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text = (TextView)findViewById(R.id.textView);
gpsLocation = new GPSLocation(this);
editLatitude = (EditText)findViewById(R.id.editDlugosc);
editLongitude = (EditText)findViewById(R.id.editSzerokosc);
targetLocation = new Location("Bosch");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void click_rozpocznij(View view) {
targetLocation=gpsLocation.getLastKnownLocation();
text.setText("Your location: \n" + gpsLocation.getLatitude() + "\n" + gpsLocation.getLongitude());
}
public void click_end(View view)
{
gpsLocation.stopUsingGPS();
text.setText("Your location:");
}
public void click_pointer(View view) {
if(targetLocation !=null) {
Intent nextScreen = new Intent(getApplicationContext(), Pointer.class);
nextScreen.putExtra("location", targetLocation);
startActivity(nextScreen);
}
else
{
targetLocation.setLongitude(0);
targetLocation.setLatitude(0);
Intent nextScreen = new Intent(getApplicationContext(), Pointer.class);
nextScreen.putExtra("location", targetLocation);
startActivity(nextScreen);
}
}
public void click_show(View view) {
gpsLocation.getLastKnownLocation();
text.setText("Your location: \n" + gpsLocation.getLatitude() + "\n" + gpsLocation.getLongitude());
}
public void click_SaveTarget(View view) {
if(targetLocation !=null)
{
try{
targetLocation.setLatitude(Double.parseDouble(editLatitude.getText().toString()));
targetLocation.setLongitude(Double.parseDouble(editLongitude.getText().toString()));
}
catch(Exception e)
{
targetLocation.setLatitude(0);
targetLocation.setLongitude(0);
editLatitude.setText("0");
editLongitude.setText("0");
}
}
}
第二个屏幕：
public class Pointer extends ActionBarActivity implements SensorEventListener{
private Location cel;
private TextView textLocation;
private TextView textDistance;
private TextView textAngle;
private TextView textAccuracy;
private ImageView obrazek;
private SensorManager sensorManager;
private float[] lastCompass= new float[3];
private float[] lastAccelero = new float[3];
private float[] orientation = new float[3];
private boolean lastCompassSet = false;
private boolean lastAcceleroSet = false;
private float[] rotation = new float[9];
private float degree = 0f;
private Sensor compass;
private Sensor accelerometer;
private GPSLocation gpsLocation;
private Location locationFirst;
private Location locationNow;
private GeomagneticField magneticField;
private float azimuthDegress;
private float azimuthCel;
private Long timeStart;
private Long timeEnd;
private void sprawdzPolozenie()
{
if (gpsLocation.location.distanceTo(locationFirst) > 10000)
{
magneticField = new GeomagneticField(Double.valueOf(gpsLocation.getLatitude()).floatValue(),Double.valueOf(gpsLocation.getLongitude()).floatValue(),Double.valueOf(gpsLocation.getAltitude()).floatValue(),System.currentTimeMillis());
locationFirst = gpsLocation.getLastKnownLocation();
}
SensorManager.getRotationMatrix(rotation,null,lastAccelero,lastCompass);
SensorManager.getOrientation(rotation,orientation);
float azimuthRadians = orientation[0];
azimuthDegress = (float)(Math.toDegrees(azimuthRadians));
azimuthDegress += magneticField.getDeclination();
azimuthCel= locationNow.bearingTo(cel);
azimuthDegress=azimuthDegress-azimuthCel;
RotateAnimation ra = new RotateAnimation(degree,-azimuthDegress, Animation.RELATIVE_TO_SELF,0.5f,Animation.RELATIVE_TO_SELF,0.5f);
ra.setDuration(400);
ra.setFillAfter(true);
obrazek.startAnimation(ra);
degree=-azimuthDegress;
}
@Override
public void onSensorChanged(SensorEvent event) {
locationNow=gpsLocation.getLastKnownLocation();
if(locationNow!=null) {
if (event.sensor == compass) {
/*event.values[0]=lastCompass[0];
event.values[1]=lastCompass[1];
event.values[2]=lastCompass[2];*/
System.arraycopy(event.values, 0, lastCompass, 0, event.values.length);
lastCompassSet = true;
} else if (event.sensor == accelerometer) {
/*event.values[0]=lastAccelero[0];
event.values[1]=lastAccelero[1];
event.values[2]=lastAccelero[2];*/
System.arraycopy(event.values, 0, lastAccelero, 0, event.values.length);
lastAcceleroSet = true;
}
if (lastCompassSet) {
timeStart = System.currentTimeMillis();
if (timeStart > timeEnd + 500) {
sprawdzPolozenie();
timeEnd = timeStart;
}
}
textDistance.setText("Distanse: " + locationNow.distanceTo(cel));
textAccuracy.setText("Accuracy: " + locationNow.getAccuracy());
textAngle.setText("Angle: " + azimuthDegress);
}
}
@Override
protected void onResume() {
super.onResume();
sensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_GAME);
sensorManager.registerListener(this, compass, SensorManager.SENSOR_DELAY_GAME);
}
@Override
protected void onPause(){
super.onPause();
sensorManager.unregisterListener(this,accelerometer);
sensorManager.unregisterListener(this,compass);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
gpsLocation = new GPSLocation(this);
locationFirst = new Location("Bosch");
locationNow = new Location("Bosch");
cel = new Location("Bosch");
locationNow=gpsLocation.getLastKnownLocation();
locationFirst= gpsLocation.getLastKnownLocation();
setContentView(R.layout.activity_wskaznik);
timeEnd =System.currentTimeMillis();
sensorManager = (SensorManager)this.getSystemService(Context.SENSOR_SERVICE);
compass = sensorManager.getDefaultSensor(TYPE_MAGNETIC_FIELD);
accelerometer = sensorManager.getDefaultSensor(TYPE_ACCELEROMETER);
obrazek =(ImageView)findViewById(R.id.wskaznik_imageView);
textLocation = (TextView)findViewById(R.id.wskaznikTekstCel);
textDistance = (TextView)findViewById(R.id.wskaznikTekstOdleglosc);
textAngle = (TextView)findViewById(R.id.wskaznikTekstKat);
textAccuracy =(TextView)findViewById(R.id.wskaznikTekstDokladnosc);
Bundle extras = getIntent().getExtras();
magneticField = new GeomagneticField(Double.valueOf(gpsLocation.getLatitude()).floatValue(),Double.valueOf(gpsLocation.getLongitude()).floatValue(),Double.valueOf(gpsLocation.getAltitude()).floatValue(),System.currentTimeMillis());
if(extras!=null)
{
cel = (Location)extras.get("location");
}
textLocation.setText(cel.getLatitude() + "," + cel.getLongitude());
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
public void click_wroc(View view) {
finish();
}
GPSLocation 本身：
public class GPSLocation extends Service implements LocationListener {
private final Context mContext;
boolean isGPSEnabled = false;
boolean isNetworkEnabled = false;
public boolean canGetLocation = false;
//czas i dystans pomiedzy pomiarami
private static final long MIN_DISTANCE = 10;
private static final long MIN_TIME = 1000 * 60 * 1;
double latitude;
double longitude;
double altitude;
public Location location;
protected LocationManager locationManager;
public GPSLocation(Context context)
{
this.mContext = context;
getLocation();
}
public void requestLocation() {
//network
if (isNetworkEnabled)
{
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, MIN_TIME, MIN_DISTANCE, this);
if (locationManager != null) {
location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
}
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
altitude = location.getAltitude();
}
}
//gps
if(isGPSEnabled)
{
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, MIN_TIME, MIN_DISTANCE, this);
if(locationManager != null)
{
location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
}
if(location!=null)
{
latitude=location.getLatitude();
longitude=location.getLongitude();
altitude = location.getAltitude();
}
}
}
public Location getLastKnownLocation()
{
try
{
isGPSEnabled=locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
isNetworkEnabled=locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if(!isGPSEnabled && !isNetworkEnabled)
{
this.canGetLocation=false;
this.showSettingsAlert();
}
else
{
requestLocation();
}
}
catch (Exception e)
{
e.printStackTrace();
}
return location;
}
public Location getLocation()
{
try
{
locationManager=(LocationManager)mContext.getSystemService(LOCATION_SERVICE);
isGPSEnabled=locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
isNetworkEnabled=locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if(!isGPSEnabled && !isNetworkEnabled)
{
this.canGetLocation=false;
this.showSettingsAlert();
}
else
{
this.canGetLocation=true;
requestLocation();
}
}
catch (Exception e)
{
e.printStackTrace();
}
return location;
}
public double getLatitude()
{
if(location!=null)
{
latitude = location.getLatitude();
}
return latitude;
}
public double getLongitude()
{
if(location!=null)
{
latitude = location.getLatitude();
}
return longitude;
}
public double getAltitude(){
if(location!=null)
{
latitude=location.getAltitude();
}
return altitude;
}
public void showSettingsAlert()
{
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
alertDialog.setTitle("Przejdź do ustawień");
alertDialog.setMessage("Lokalizacja wyłączona");
// On pressing Settings button
alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
}
});
// on pressing cancel button
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
alertDialog.show();
}
public void stopUsingGPS()
{
if(locationManager!=null)
{
locationManager.removeUpdates(GPSLocation.this);
}
}
@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) {
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
我 运行 你的 Pointer Activity 代码是孤立的，它对我来说工作得很好。
看来您的主要问题是如何将 Location 通过 Intent 传递到 Pointer Activity 从 MainActivity。
Location 实现了 Parcelable，因此您可以像您已经在做的那样通过 Intent 传递它，并像这样检索它：
if(extras!=null)
{
//cel = (Location)extras.get("location"); //this is not correct
cel = (Location) extras.getParcelable("location");
}
if (cel != null){
textLocation.setText(cel.getLatitude() + "," + cel.getLongitude());
}
文档：http://developer.android.com/reference/android/os/Bundle.html#getParcelable(java.lang.String)
http://developer.android.com/reference/android/location/Location.html
对所有想帮助我解决问题的人表示抱歉。我自己解决了这个问题。
问题出在 GPSLocation class。我必须在开始时添加新的构造函数并更改从 locationManager
获取位置的方式
public GPSLocation(Context context)
{
this.mContext = context;
location = new Location("Bosch");
getLocation();
}
当我使用此代码位置时保持空指针。
location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
但是从 locationManager 创建位置副本解决了问题。
location = new Location(locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER));
也许 locationManager 正在创建位置数据而不是 Location 本身，这导致创建了空指针。
我的 Android 应用程序中的位置变量有问题。在此屏幕上 GPSLocation 工作正常，但是当我将屏幕更改为 gpsLocation.getLastKnownLocation() 时，此方法始终 returns null.
第一个屏幕：
public class MainActivity extends ActionBarActivity {
private TextView text;
private GPSLocation gpsLocation;
private Location targetLocation;
private EditText editLatitude;
private EditText editLongitude;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text = (TextView)findViewById(R.id.textView);
gpsLocation = new GPSLocation(this);
editLatitude = (EditText)findViewById(R.id.editDlugosc);
editLongitude = (EditText)findViewById(R.id.editSzerokosc);
targetLocation = new Location("Bosch");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void click_rozpocznij(View view) {
targetLocation=gpsLocation.getLastKnownLocation();
text.setText("Your location: \n" + gpsLocation.getLatitude() + "\n" + gpsLocation.getLongitude());
}
public void click_end(View view)
{
gpsLocation.stopUsingGPS();
text.setText("Your location:");
}
public void click_pointer(View view) {
if(targetLocation !=null) {
Intent nextScreen = new Intent(getApplicationContext(), Pointer.class);
nextScreen.putExtra("location", targetLocation);
startActivity(nextScreen);
}
else
{
targetLocation.setLongitude(0);
targetLocation.setLatitude(0);
Intent nextScreen = new Intent(getApplicationContext(), Pointer.class);
nextScreen.putExtra("location", targetLocation);
startActivity(nextScreen);
}
}
public void click_show(View view) {
gpsLocation.getLastKnownLocation();
text.setText("Your location: \n" + gpsLocation.getLatitude() + "\n" + gpsLocation.getLongitude());
}
public void click_SaveTarget(View view) {
if(targetLocation !=null)
{
try{
targetLocation.setLatitude(Double.parseDouble(editLatitude.getText().toString()));
targetLocation.setLongitude(Double.parseDouble(editLongitude.getText().toString()));
}
catch(Exception e)
{
targetLocation.setLatitude(0);
targetLocation.setLongitude(0);
editLatitude.setText("0");
editLongitude.setText("0");
}
}
}
第二个屏幕：
public class Pointer extends ActionBarActivity implements SensorEventListener{
private Location cel;
private TextView textLocation;
private TextView textDistance;
private TextView textAngle;
private TextView textAccuracy;
private ImageView obrazek;
private SensorManager sensorManager;
private float[] lastCompass= new float[3];
private float[] lastAccelero = new float[3];
private float[] orientation = new float[3];
private boolean lastCompassSet = false;
private boolean lastAcceleroSet = false;
private float[] rotation = new float[9];
private float degree = 0f;
private Sensor compass;
private Sensor accelerometer;
private GPSLocation gpsLocation;
private Location locationFirst;
private Location locationNow;
private GeomagneticField magneticField;
private float azimuthDegress;
private float azimuthCel;
private Long timeStart;
private Long timeEnd;
private void sprawdzPolozenie()
{
if (gpsLocation.location.distanceTo(locationFirst) > 10000)
{
magneticField = new GeomagneticField(Double.valueOf(gpsLocation.getLatitude()).floatValue(),Double.valueOf(gpsLocation.getLongitude()).floatValue(),Double.valueOf(gpsLocation.getAltitude()).floatValue(),System.currentTimeMillis());
locationFirst = gpsLocation.getLastKnownLocation();
}
SensorManager.getRotationMatrix(rotation,null,lastAccelero,lastCompass);
SensorManager.getOrientation(rotation,orientation);
float azimuthRadians = orientation[0];
azimuthDegress = (float)(Math.toDegrees(azimuthRadians));
azimuthDegress += magneticField.getDeclination();
azimuthCel= locationNow.bearingTo(cel);
azimuthDegress=azimuthDegress-azimuthCel;
RotateAnimation ra = new RotateAnimation(degree,-azimuthDegress, Animation.RELATIVE_TO_SELF,0.5f,Animation.RELATIVE_TO_SELF,0.5f);
ra.setDuration(400);
ra.setFillAfter(true);
obrazek.startAnimation(ra);
degree=-azimuthDegress;
}
@Override
public void onSensorChanged(SensorEvent event) {
locationNow=gpsLocation.getLastKnownLocation();
if(locationNow!=null) {
if (event.sensor == compass) {
/*event.values[0]=lastCompass[0];
event.values[1]=lastCompass[1];
event.values[2]=lastCompass[2];*/
System.arraycopy(event.values, 0, lastCompass, 0, event.values.length);
lastCompassSet = true;
} else if (event.sensor == accelerometer) {
/*event.values[0]=lastAccelero[0];
event.values[1]=lastAccelero[1];
event.values[2]=lastAccelero[2];*/
System.arraycopy(event.values, 0, lastAccelero, 0, event.values.length);
lastAcceleroSet = true;
}
if (lastCompassSet) {
timeStart = System.currentTimeMillis();
if (timeStart > timeEnd + 500) {
sprawdzPolozenie();
timeEnd = timeStart;
}
}
textDistance.setText("Distanse: " + locationNow.distanceTo(cel));
textAccuracy.setText("Accuracy: " + locationNow.getAccuracy());
textAngle.setText("Angle: " + azimuthDegress);
}
}
@Override
protected void onResume() {
super.onResume();
sensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_GAME);
sensorManager.registerListener(this, compass, SensorManager.SENSOR_DELAY_GAME);
}
@Override
protected void onPause(){
super.onPause();
sensorManager.unregisterListener(this,accelerometer);
sensorManager.unregisterListener(this,compass);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
gpsLocation = new GPSLocation(this);
locationFirst = new Location("Bosch");
locationNow = new Location("Bosch");
cel = new Location("Bosch");
locationNow=gpsLocation.getLastKnownLocation();
locationFirst= gpsLocation.getLastKnownLocation();
setContentView(R.layout.activity_wskaznik);
timeEnd =System.currentTimeMillis();
sensorManager = (SensorManager)this.getSystemService(Context.SENSOR_SERVICE);
compass = sensorManager.getDefaultSensor(TYPE_MAGNETIC_FIELD);
accelerometer = sensorManager.getDefaultSensor(TYPE_ACCELEROMETER);
obrazek =(ImageView)findViewById(R.id.wskaznik_imageView);
textLocation = (TextView)findViewById(R.id.wskaznikTekstCel);
textDistance = (TextView)findViewById(R.id.wskaznikTekstOdleglosc);
textAngle = (TextView)findViewById(R.id.wskaznikTekstKat);
textAccuracy =(TextView)findViewById(R.id.wskaznikTekstDokladnosc);
Bundle extras = getIntent().getExtras();
magneticField = new GeomagneticField(Double.valueOf(gpsLocation.getLatitude()).floatValue(),Double.valueOf(gpsLocation.getLongitude()).floatValue(),Double.valueOf(gpsLocation.getAltitude()).floatValue(),System.currentTimeMillis());
if(extras!=null)
{
cel = (Location)extras.get("location");
}
textLocation.setText(cel.getLatitude() + "," + cel.getLongitude());
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
public void click_wroc(View view) {
finish();
}
GPSLocation 本身：
public class GPSLocation extends Service implements LocationListener {
private final Context mContext;
boolean isGPSEnabled = false;
boolean isNetworkEnabled = false;
public boolean canGetLocation = false;
//czas i dystans pomiedzy pomiarami
private static final long MIN_DISTANCE = 10;
private static final long MIN_TIME = 1000 * 60 * 1;
double latitude;
double longitude;
double altitude;
public Location location;
protected LocationManager locationManager;
public GPSLocation(Context context)
{
this.mContext = context;
getLocation();
}
public void requestLocation() {
//network
if (isNetworkEnabled)
{
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, MIN_TIME, MIN_DISTANCE, this);
if (locationManager != null) {
location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
}
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
altitude = location.getAltitude();
}
}
//gps
if(isGPSEnabled)
{
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, MIN_TIME, MIN_DISTANCE, this);
if(locationManager != null)
{
location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
}
if(location!=null)
{
latitude=location.getLatitude();
longitude=location.getLongitude();
altitude = location.getAltitude();
}
}
}
public Location getLastKnownLocation()
{
try
{
isGPSEnabled=locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
isNetworkEnabled=locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if(!isGPSEnabled && !isNetworkEnabled)
{
this.canGetLocation=false;
this.showSettingsAlert();
}
else
{
requestLocation();
}
}
catch (Exception e)
{
e.printStackTrace();
}
return location;
}
public Location getLocation()
{
try
{
locationManager=(LocationManager)mContext.getSystemService(LOCATION_SERVICE);
isGPSEnabled=locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
isNetworkEnabled=locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if(!isGPSEnabled && !isNetworkEnabled)
{
this.canGetLocation=false;
this.showSettingsAlert();
}
else
{
this.canGetLocation=true;
requestLocation();
}
}
catch (Exception e)
{
e.printStackTrace();
}
return location;
}
public double getLatitude()
{
if(location!=null)
{
latitude = location.getLatitude();
}
return latitude;
}
public double getLongitude()
{
if(location!=null)
{
latitude = location.getLatitude();
}
return longitude;
}
public double getAltitude(){
if(location!=null)
{
latitude=location.getAltitude();
}
return altitude;
}
public void showSettingsAlert()
{
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
alertDialog.setTitle("Przejdź do ustawień");
alertDialog.setMessage("Lokalizacja wyłączona");
// On pressing Settings button
alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
}
});
// on pressing cancel button
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
alertDialog.show();
}
public void stopUsingGPS()
{
if(locationManager!=null)
{
locationManager.removeUpdates(GPSLocation.this);
}
}
@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) {
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
我 运行 你的 Pointer Activity 代码是孤立的，它对我来说工作得很好。
看来您的主要问题是如何将 Location 通过 Intent 传递到 Pointer Activity 从 MainActivity。
Location 实现了 Parcelable，因此您可以像您已经在做的那样通过 Intent 传递它，并像这样检索它：
if(extras!=null)
{
//cel = (Location)extras.get("location"); //this is not correct
cel = (Location) extras.getParcelable("location");
}
if (cel != null){
textLocation.setText(cel.getLatitude() + "," + cel.getLongitude());
}
文档：http://developer.android.com/reference/android/os/Bundle.html#getParcelable(java.lang.String)
http://developer.android.com/reference/android/location/Location.html
对所有想帮助我解决问题的人表示抱歉。我自己解决了这个问题。 问题出在 GPSLocation class。我必须在开始时添加新的构造函数并更改从 locationManager
获取位置的方式public GPSLocation(Context context)
{
this.mContext = context;
location = new Location("Bosch");
getLocation();
}
当我使用此代码位置时保持空指针。
location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
但是从 locationManager 创建位置副本解决了问题。
location = new Location(locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER));
也许 locationManager 正在创建位置数据而不是 Location 本身，这导致创建了空指针。