xref: /frameworks/base/location/java/android/location/LocationManager.java

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.location;

import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.os.Looper;
import android.os.RemoteException;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.util.Log;

import com.android.internal.location.DummyLocationProvider;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

/**
 * This class provides access to the system location services.  These
 * services allow applications to obtain periodic updates of the
 * device's geographical location, or to fire an application-specified
 * {@link Intent} when the device enters the proximity of a given
 * geographical location.
 *
 * <p>You do not
 * instantiate this class directly; instead, retrieve it through
 * {@link android.content.Context#getSystemService
 * Context.getSystemService(Context.LOCATION_SERVICE)}.
 *
 * <div class="special reference">
 * <h3>Developer Guides</h3>
 * <p>For more information about using location services, read the
 * <a href="{@docRoot}guide/topics/location/index.html">Location and Maps</a>
 * developer guide.</p>
 * </div>
 */
public class LocationManager {
    private static final String TAG = "LocationManager";

    private final Context mContext;
    private final ILocationManager mService;
    private final HashMap<GpsStatus.Listener, GpsStatusListenerTransport> mGpsStatusListeners =
            new HashMap<GpsStatus.Listener, GpsStatusListenerTransport>();
    private final HashMap<GpsStatus.NmeaListener, GpsStatusListenerTransport> mNmeaListeners =
            new HashMap<GpsStatus.NmeaListener, GpsStatusListenerTransport>();
    private final GpsStatus mGpsStatus = new GpsStatus();

    /**
     * Name of the network location provider.  This provider determines location based on
     * availability of cell tower and WiFi access points. Results are retrieved
     * by means of a network lookup.
     *
     * Requires either of the permissions android.permission.ACCESS_COARSE_LOCATION
     * or android.permission.ACCESS_FINE_LOCATION.
     */
    public static final String NETWORK_PROVIDER = "network";

    /**
     * Name of the GPS location provider. This provider determines location using
     * satellites. Depending on conditions, this provider may take a while to return
     * a location fix.
     *
     * Requires the permission android.permission.ACCESS_FINE_LOCATION.
     *
     * <p> The extras Bundle for the GPS location provider can contain the
     * following key/value pairs:
     *
     * <ul>
     * <li> satellites - the number of satellites used to derive the fix
     * </ul>
     */
    public static final String GPS_PROVIDER = "gps";

    /**
     * A special location provider for receiving locations without actually initiating
     * a location fix. This provider can be used to passively receive location updates
     * when other applications or services request them without actually requesting
     * the locations yourself.  This provider will return locations generated by other
     * providers.  You can query the {@link Location#getProvider()} method to determine
     * the origin of the location update.
     *
     * Requires the permission android.permission.ACCESS_FINE_LOCATION, although if the GPS
     * is not enabled this provider might only return coarse fixes.
     */
    public static final String PASSIVE_PROVIDER = "passive";

    /**
     * Key used for the Bundle extra holding a boolean indicating whether
     * a proximity alert is entering (true) or exiting (false)..
     */
    public static final String KEY_PROXIMITY_ENTERING = "entering";

    /**
     * Key used for a Bundle extra holding an Integer status value
     * when a status change is broadcast using a PendingIntent.
     */
    public static final String KEY_STATUS_CHANGED = "status";

    /**
     * Key used for a Bundle extra holding an Boolean status value
     * when a provider enabled/disabled event is broadcast using a PendingIntent.
     */
    public static final String KEY_PROVIDER_ENABLED = "providerEnabled";

    /**
     * Key used for a Bundle extra holding a Location value
     * when a location change is broadcast using a PendingIntent.
     */
    public static final String KEY_LOCATION_CHANGED = "location";

    /**
     * Broadcast intent action indicating that the GPS has either been
     * enabled or disabled. An intent extra provides this state as a boolean,
     * where {@code true} means enabled.
     * @see #EXTRA_GPS_ENABLED
     *
     * {@hide}
     */
    public static final String GPS_ENABLED_CHANGE_ACTION =
        "android.location.GPS_ENABLED_CHANGE";

    /**
     * Broadcast intent action when the configured location providers
     * change.
     */
    public static final String PROVIDERS_CHANGED_ACTION =
        "android.location.PROVIDERS_CHANGED";

    /**
     * Broadcast intent action indicating that the GPS has either started or
     * stopped receiving GPS fixes. An intent extra provides this state as a
     * boolean, where {@code true} means that the GPS is actively receiving fixes.
     * @see #EXTRA_GPS_ENABLED
     *
     * {@hide}
     */
    public static final String GPS_FIX_CHANGE_ACTION =
        "android.location.GPS_FIX_CHANGE";

    /**
     * The lookup key for a boolean that indicates whether GPS is enabled or
     * disabled. {@code true} means GPS is enabled. Retrieve it with
     * {@link android.content.Intent#getBooleanExtra(String,boolean)}.
     *
     * {@hide}
     */
    public static final String EXTRA_GPS_ENABLED = "enabled";

    // Map from LocationListeners to their associated ListenerTransport objects
    private HashMap<LocationListener,ListenerTransport> mListeners =
        new HashMap<LocationListener,ListenerTransport>();

    private class ListenerTransport extends ILocationListener.Stub {
        private static final int TYPE_LOCATION_CHANGED = 1;
        private static final int TYPE_STATUS_CHANGED = 2;
        private static final int TYPE_PROVIDER_ENABLED = 3;
        private static final int TYPE_PROVIDER_DISABLED = 4;

        private LocationListener mListener;
        private final Handler mListenerHandler;

        ListenerTransport(LocationListener listener, Looper looper) {
            mListener = listener;

            if (looper == null) {
                mListenerHandler = new Handler() {
                    @Override
                    public void handleMessage(Message msg) {
                        _handleMessage(msg);
                    }
                };
            } else {
                mListenerHandler = new Handler(looper) {
                    @Override
                    public void handleMessage(Message msg) {
                        _handleMessage(msg);
                    }
                };
            }
        }

        @Override
        public void onLocationChanged(Location location) {
            Message msg = Message.obtain();
            msg.what = TYPE_LOCATION_CHANGED;
            msg.obj = location;
            mListenerHandler.sendMessage(msg);
        }

        @Override
        public void onStatusChanged(String provider, int status, Bundle extras) {
            Message msg = Message.obtain();
            msg.what = TYPE_STATUS_CHANGED;
            Bundle b = new Bundle();
            b.putString("provider", provider);
            b.putInt("status", status);
            if (extras != null) {
                b.putBundle("extras", extras);
            }
            msg.obj = b;
            mListenerHandler.sendMessage(msg);
        }

        @Override
        public void onProviderEnabled(String provider) {
            Message msg = Message.obtain();
            msg.what = TYPE_PROVIDER_ENABLED;
            msg.obj = provider;
            mListenerHandler.sendMessage(msg);
        }

        @Override
        public void onProviderDisabled(String provider) {
            Message msg = Message.obtain();
            msg.what = TYPE_PROVIDER_DISABLED;
            msg.obj = provider;
            mListenerHandler.sendMessage(msg);
        }

        private void _handleMessage(Message msg) {
            switch (msg.what) {
                case TYPE_LOCATION_CHANGED:
                    Location location = new Location((Location) msg.obj);
                    mListener.onLocationChanged(location);
                    break;
                case TYPE_STATUS_CHANGED:
                    Bundle b = (Bundle) msg.obj;
                    String provider = b.getString("provider");
                    int status = b.getInt("status");
                    Bundle extras = b.getBundle("extras");
                    mListener.onStatusChanged(provider, status, extras);
                    break;
                case TYPE_PROVIDER_ENABLED:
                    mListener.onProviderEnabled((String) msg.obj);
                    break;
                case TYPE_PROVIDER_DISABLED:
                    mListener.onProviderDisabled((String) msg.obj);
                    break;
            }
            try {
                mService.locationCallbackFinished(this);
            } catch (RemoteException e) {
                Log.e(TAG, "locationCallbackFinished: RemoteException", e);
            }
        }
    }
    /**
     * @hide - hide this constructor because it has a parameter
     * of type ILocationManager, which is a system private class. The
     * right way to create an instance of this class is using the
     * factory Context.getSystemService.
     */
    public LocationManager(Context context, ILocationManager service) {
        mService = service;
        mContext = context;
    }

    private LocationProvider createProvider(String name, Bundle info) {
        DummyLocationProvider provider =
            new DummyLocationProvider(name, mService);
        provider.setRequiresNetwork(info.getBoolean("network"));
        provider.setRequiresSatellite(info.getBoolean("satellite"));
        provider.setRequiresCell(info.getBoolean("cell"));
        provider.setHasMonetaryCost(info.getBoolean("cost"));
        provider.setSupportsAltitude(info.getBoolean("altitude"));
        provider.setSupportsSpeed(info.getBoolean("speed"));
        provider.setSupportsBearing(info.getBoolean("bearing"));
        provider.setPowerRequirement(info.getInt("power"));
        provider.setAccuracy(info.getInt("accuracy"));
        return provider;
    }

    /**
     * Returns a list of the names of all known location providers.  All
     * providers are returned, including ones that are not permitted to be
     * accessed by the calling activity or are currently disabled.
     *
     * @return list of Strings containing names of the providers
     */
    public List<String> getAllProviders() {
        if (false) {
            Log.d(TAG, "getAllProviders");
        }
        try {
            return mService.getAllProviders();
        } catch (RemoteException ex) {
            Log.e(TAG, "getAllProviders: RemoteException", ex);
        }
        return null;
    }

    /**
     * Returns a list of the names of location providers.  Only providers that
     * are permitted to be accessed by the calling activity will be returned.
     *
     * @param enabledOnly if true then only the providers which are currently
     * enabled are returned.
     * @return list of Strings containing names of the providers
     */
    public List<String> getProviders(boolean enabledOnly) {
        try {
            return mService.getProviders(null, enabledOnly);
        } catch (RemoteException ex) {
            Log.e(TAG, "getProviders: RemoteException", ex);
        }
        return null;
    }

    /**
     * Returns the information associated with the location provider of the
     * given name, or null if no provider exists by that name.
     *
     * @param name the provider name
     * @return a LocationProvider, or null
     *
     * @throws IllegalArgumentException if name is null
     * @throws SecurityException if the caller is not permitted to access the
     * given provider.
     */
    public LocationProvider getProvider(String name) {
        if (name == null) {
            throw new IllegalArgumentException("name==null");
        }
        try {
            Bundle info = mService.getProviderInfo(name);
            if (info == null) {
                return null;
            }
            return createProvider(name, info);
        } catch (RemoteException ex) {
            Log.e(TAG, "getProvider: RemoteException", ex);
        }
        return null;
    }

    /**
     * Returns a list of the names of LocationProviders that satisfy the given
     * criteria, or null if none do.  Only providers that are permitted to be
     * accessed by the calling activity will be returned.
     *
     * @param criteria the criteria that the returned providers must match
     * @param enabledOnly if true then only the providers which are currently
     * enabled are returned.
     * @return list of Strings containing names of the providers
     */
    public List<String> getProviders(Criteria criteria, boolean enabledOnly) {
        if (criteria == null) {
            throw new IllegalArgumentException("criteria==null");
        }
        try {
            return mService.getProviders(criteria, enabledOnly);
        } catch (RemoteException ex) {
            Log.e(TAG, "getProviders: RemoteException", ex);
        }
        return null;
    }

    /**
     * Returns the name of the provider that best meets the given criteria. Only providers
     * that are permitted to be accessed by the calling activity will be
     * returned.  If several providers meet the criteria, the one with the best
     * accuracy is returned.  If no provider meets the criteria,
     * the criteria are loosened in the following sequence:
     *
     * <ul>
     * <li> power requirement
     * <li> accuracy
     * <li> bearing
     * <li> speed
     * <li> altitude
     * </ul>
     *
     * <p> Note that the requirement on monetary cost is not removed
     * in this process.
     *
     * @param criteria the criteria that need to be matched
     * @param enabledOnly if true then only a provider that is currently enabled is returned
     * @return name of the provider that best matches the requirements
     */
    public String getBestProvider(Criteria criteria, boolean enabledOnly) {
        if (criteria == null) {
            throw new IllegalArgumentException("criteria==null");
        }
        try {
            return mService.getBestProvider(criteria, enabledOnly);
        } catch (RemoteException ex) {
            Log.e(TAG, "getBestProvider: RemoteException", ex);
        }
        return null;
    }

    /**
     * Registers the current activity to be notified periodically by
     * the named provider.  Periodically, the supplied LocationListener will
     * be called with the current Location or with status updates.
     *
     * <p> It may take a while to receive the first location update. If
     * an immediate location is required, applications may use the
     * {@link #getLastKnownLocation(String)} method.
     *
     * <p> In case the provider is disabled by the user, updates will stop,
     * and the {@link LocationListener#onProviderDisabled(String)}
     * method will be called. As soon as the provider is enabled again,
     * the {@link LocationListener#onProviderEnabled(String)} method will
     * be called and location updates will start again.
     *
     * <p> The update interval can be controlled using the minTime parameter.
     * The elapsed time between location updates will never be less than
     * minTime, although it can be more depending on the Location Provider
     * implementation and the update interval requested by other applications.
     *
     * <p> Choosing a sensible value for minTime is important to conserve
     * battery life. Each location update requires power from
     * GPS, WIFI, Cell and other radios. Select a minTime value as high as
     * possible while still providing a reasonable user experience.
     * If your application is not in the foreground and showing
     * location to the user then your application should avoid using an active
     * provider (such as {@link #NETWORK_PROVIDER} or {@link #GPS_PROVIDER}),
     * but if you insist then select a minTime of 5 * 60 * 1000 (5 minutes)
     * or greater. If your application is in the foreground and showing
     * location to the user then it is appropriate to select a faster
     * update interval.
     *
     * <p> The minDistance parameter can also be used to control the
     * frequency of location updates. If it is greater than 0 then the
     * location provider will only send your application an update when
     * the location has changed by at least minDistance meters, AND
     * at least minTime milliseconds have passed. However it is more
     * difficult for location providers to save power using the minDistance
     * parameter, so minTime should be the primary tool to conserving battery
     * life.
     *
     * <p> If your application wants to passively observe location
     * updates triggered by other applications, but not consume
     * any additional power otherwise, then use the {@link #PASSIVE_PROVIDER}
     * This provider does not actively turn on or modify active location
     * providers, so you do not need to be as careful about minTime and
     * minDistance. However if your application performs heavy work
     * on a location update (such as network activity) then you should
     * select non-zero values for minTime and/or minDistance to rate-limit
     * your update frequency in the case another application enables a
     * location provider with extremely fast updates.
     *
     * <p> The calling thread must be a {@link android.os.Looper} thread such as
     * the main thread of the calling Activity.
     *
     * <p class="note"> Prior to Jellybean, the minTime parameter was
     * only a hint, and some location provider implementations ignored it.
     * From Jellybean and onwards it is mandatory for Android compatible
     * devices to observe both the minTime and minDistance parameters.
     *
     * @param provider the name of the provider with which to register
     * @param minTime minimum time interval between location updates, in milliseconds
     * @param minDistance minimum distance between location updates, in meters
     * @param listener a {#link LocationListener} whose
     * {@link LocationListener#onLocationChanged} method will be called for
     * each location update
     *
     * @throws IllegalArgumentException if provider is null or doesn't exist
     * on this device
     * @throws IllegalArgumentException if listener is null
     * @throws RuntimeException if the calling thread has no Looper
     * @throws SecurityException if no suitable permission is present for the provider.
     */
    public void requestLocationUpdates(String provider,
        long minTime, float minDistance, LocationListener listener) {
        if (provider == null) {
            throw new IllegalArgumentException("provider==null");
        }
        if (listener == null) {
            throw new IllegalArgumentException("listener==null");
        }
        _requestLocationUpdates(provider, null, minTime, minDistance, false, listener, null);
    }

    /**
     * Registers the current activity to be notified periodically by
     * the named provider.  Periodically, the supplied LocationListener will
     * be called with the current Location or with status updates.
     *
     * <p> It may take a while to receive the first location update. If
     * an immediate location is required, applications may use the
     * {@link #getLastKnownLocation(String)} method.
     *
     * <p> In case the provider is disabled by the user, updates will stop,
     * and the {@link LocationListener#onProviderDisabled(String)}
     * method will be called. As soon as the provider is enabled again,
     * the {@link LocationListener#onProviderEnabled(String)} method will
     * be called and location updates will start again.
     *
     * <p> The update interval can be controlled using the minTime parameter.
     * The elapsed time between location updates will never be less than
     * minTime, although it can be more depending on the Location Provider
     * implementation and the update interval requested by other applications.
     *
     * <p> Choosing a sensible value for minTime is important to conserve
     * battery life. Each location update requires power from
     * GPS, WIFI, Cell and other radios. Select a minTime value as high as
     * possible while still providing a reasonable user experience.
     * If your application is not in the foreground and showing
     * location to the user then your application should avoid using an active
     * provider (such as {@link #NETWORK_PROVIDER} or {@link #GPS_PROVIDER}),
     * but if you insist then select a minTime of 5 * 60 * 1000 (5 minutes)
     * or greater. If your application is in the foreground and showing
     * location to the user then it is appropriate to select a faster
     * update interval.
     *
     * <p> The minDistance parameter can also be used to control the
     * frequency of location updates. If it is greater than 0 then the
     * location provider will only send your application an update when
     * the location has changed by at least minDistance meters, AND
     * at least minTime milliseconds have passed. However it is more
     * difficult for location providers to save power using the minDistance
     * parameter, so minTime should be the primary tool to conserving battery
     * life.
     *
     * <p> If your application wants to passively observe location
     * updates triggered by other applications, but not consume
     * any additional power otherwise, then use the {@link #PASSIVE_PROVIDER}
     * This provider does not actively turn on or modify active location
     * providers, so you do not need to be as careful about minTime and
     * minDistance. However if your application performs heavy work
     * on a location update (such as network activity) then you should
     * select non-zero values for minTime and/or minDistance to rate-limit
     * your update frequency in the case another application enables a
     * location provider with extremely fast updates.
     *
     * <p> The supplied Looper is used to implement the callback mechanism.
     *
     * <p class="note"> Prior to Jellybean, the minTime parameter was
     * only a hint, and some location provider implementations ignored it.
     * From Jellybean and onwards it is mandatory for Android compatible
     * devices to observe both the minTime and minDistance parameters.
     *
     * @param provider the name of the provider with which to register
     * @param minTime minimum time interval between location updates, in milliseconds
     * @param minDistance minimum distance between location updates, in meters
     * @param listener a {#link LocationListener} whose
     * {@link LocationListener#onLocationChanged} method will be called for
     * each location update
     * @param looper a Looper object whose message queue will be used to
     * implement the callback mechanism, or null to make callbacks on the
     * main thread
     *
     * @throws IllegalArgumentException if provider is null or doesn't exist
     * @throws IllegalArgumentException if listener is null
     * @throws SecurityException if no suitable permission is present for the provider.
     */
    public void requestLocationUpdates(String provider,
        long minTime, float minDistance, LocationListener listener,
        Looper looper) {
        if (provider == null) {
            throw new IllegalArgumentException("provider==null");
        }
        if (listener == null) {
            throw new IllegalArgumentException("listener==null");
        }
        _requestLocationUpdates(provider, null, minTime, minDistance, false, listener, looper);
    }

    /**
     * Registers the current activity to be notified periodically based on
     * the supplied criteria.  Periodically, the supplied LocationListener will
     * be called with the current Location or with status updates.
     *
     * <p> It may take a while to receive the first location update. If
     * an immediate location is required, applications may use the
     * {@link #getLastKnownLocation(String)} method.
     *
     * <p> In case the provider is disabled by the user, updates will stop,
     * and the {@link LocationListener#onProviderDisabled(String)}
     * method will be called. As soon as the provider is enabled again,
     * the {@link LocationListener#onProviderEnabled(String)} method will
     * be called and location updates will start again.
     *
     * <p> The update interval can be controlled using the minTime parameter.
     * The elapsed time between location updates will never be less than
     * minTime, although it can be more depending on the Location Provider
     * implementation and the update interval requested by other applications.
     *
     * <p> Choosing a sensible value for minTime is important to conserve
     * battery life. Each location update requires power from
     * GPS, WIFI, Cell and other radios. Select a minTime value as high as
     * possible while still providing a reasonable user experience.
     * If your application is not in the foreground and showing
     * location to the user then your application should avoid using an active
     * provider (such as {@link #NETWORK_PROVIDER} or {@link #GPS_PROVIDER}),
     * but if you insist then select a minTime of 5 * 60 * 1000 (5 minutes)
     * or greater. If your application is in the foreground and showing
     * location to the user then it is appropriate to select a faster
     * update interval.
     *
     * <p> The minDistance parameter can also be used to control the
     * frequency of location updates. If it is greater than 0 then the
     * location provider will only send your application an update when
     * the location has changed by at least minDistance meters, AND
     * at least minTime milliseconds have passed. However it is more
     * difficult for location providers to save power using the minDistance
     * parameter, so minTime should be the primary tool to conserving battery
     * life.
     *
     * <p> The supplied Looper is used to implement the callback mechanism.
     *
     * <p class="note"> Prior to Jellybean, the minTime parameter was
     * only a hint, and some location provider implementations ignored it.
     * From Jellybean and onwards it is mandatory for Android compatible
     * devices to observe both the minTime and minDistance parameters.
     *
     * @param minTime minimum time interval between location updates, in milliseconds
     * @param minDistance minimum distance between location updates, in meters
     * @param criteria contains parameters for the location manager to choose the
     * appropriate provider and parameters to compute the location
     * @param listener a {#link LocationListener} whose
     * {@link LocationListener#onLocationChanged} method will be called for
     * each location update
     * @param looper a Looper object whose message queue will be used to
     * implement the callback mechanism, or null to make callbacks on the
     * main thread.
     *
     * @throws IllegalArgumentException if criteria is null
     * @throws IllegalArgumentException if listener is null
     * @throws SecurityException if no suitable permission is present for the provider.
     */
    public void requestLocationUpdates(long minTime, float minDistance,
            Criteria criteria, LocationListener listener, Looper looper) {
        if (criteria == null) {
            throw new IllegalArgumentException("criteria==null");
        }
        if (listener == null) {
            throw new IllegalArgumentException("listener==null");
        }
        _requestLocationUpdates(null, criteria, minTime, minDistance, false, listener, looper);
    }

    private void _requestLocationUpdates(String provider, Criteria criteria, long minTime,
            float minDistance, boolean singleShot, LocationListener listener, Looper looper) {
        if (minTime < 0L) {
            minTime = 0L;
        }
        if (minDistance < 0.0f) {
            minDistance = 0.0f;
        }

        try {
            synchronized (mListeners) {
                ListenerTransport transport = mListeners.get(listener);
                if (transport == null) {
                    transport = new ListenerTransport(listener, looper);
                }
                mListeners.put(listener, transport);
                mService.requestLocationUpdates(provider, criteria, minTime, minDistance, singleShot, transport);
            }
        } catch (RemoteException ex) {
            Log.e(TAG, "requestLocationUpdates: DeadObjectException", ex);
        }
    }

    /**
     * Registers the current activity to be notified periodically by
     * the named provider.  Periodically, the supplied PendingIntent will
     * be broadcast with the current Location or with status updates.
     *
     * <p> Location updates are sent with a key of
     * {@link #KEY_LOCATION_CHANGED} and a {@link android.location.Location} value.
     *
     * <p> It may take a while to receive the first location update. If
     * an immediate location is required, applications may use the
     * {@link #getLastKnownLocation(String)} method.
     *
     * <p> The update interval can be controlled using the minTime parameter.
     * The elapsed time between location updates will never be less than
     * minTime, although it can be more depending on the Location Provider
     * implementation and the update interval requested by other applications.
     *
     * <p> Choosing a sensible value for minTime is important to conserve
     * battery life. Each location update requires power from
     * GPS, WIFI, Cell and other radios. Select a minTime value as high as
     * possible while still providing a reasonable user experience.
     * If your application is not in the foreground and showing
     * location to the user then your application should avoid using an active
     * provider (such as {@link #NETWORK_PROVIDER} or {@link #GPS_PROVIDER}),
     * but if you insist then select a minTime of 5 * 60 * 1000 (5 minutes)
     * or greater. If your application is in the foreground and showing
     * location to the user then it is appropriate to select a faster
     * update interval.
     *
     * <p> The minDistance parameter can also be used to control the
     * frequency of location updates. If it is greater than 0 then the
     * location provider will only send your application an update when
     * the location has changed by at least minDistance meters, AND
     * at least minTime milliseconds have passed. However it is more
     * difficult for location providers to save power using the minDistance
     * parameter, so minTime should be the primary tool to conserving battery
     * life.
     *
     * <p> If your application wants to passively observe location
     * updates triggered by other applications, but not consume
     * any additional power otherwise, then use the {@link #PASSIVE_PROVIDER}
     * This provider does not actively turn on or modify active location
     * providers, so you do not need to be as careful about minTime and
     * minDistance. However if your application performs heavy work
     * on a location update (such as network activity) then you should
     * select non-zero values for minTime and/or minDistance to rate-limit
     * your update frequency in the case another application enables a
     * location provider with extremely fast updates.
     *
     * <p> If the provider is disabled by the user, updates will stop,
     * and an intent will be sent with an extra with key
     * {@link #KEY_PROVIDER_ENABLED} and a boolean value of false.
     * If the provider is re-enabled, an intent will be sent with an
     * extra with key {@link #KEY_PROVIDER_ENABLED} and a boolean value of
     * true and location updates will start again.
     *
     * <p> If the provider's status changes, an intent will be sent with
     * an extra with key {@link #KEY_STATUS_CHANGED} and an integer value
     * indicating the new status.  Any extras associated with the status
     * update will be sent as well.
     *
     * <p class="note"> Prior to Jellybean, the minTime parameter was
     * only a hint, and some location provider implementations ignored it.
     * From Jellybean and onwards it is mandatory for Android compatible
     * devices to observe both the minTime and minDistance parameters.
     *
     * @param provider the name of the provider with which to register
     * @param minTime minimum time interval between location updates, in milliseconds
     * @param minDistance minimum distance between location updates, in meters
     * @param intent a {#link PendingIntent} to be sent for each location update
     *
     * @throws IllegalArgumentException if provider is null or doesn't exist
     * on this device
     * @throws IllegalArgumentException if intent is null
     * @throws SecurityException if no suitable permission is present for the provider.
     */
    public void requestLocationUpdates(String provider,
            long minTime, float minDistance, PendingIntent intent) {
        if (provider == null) {
            throw new IllegalArgumentException("provider==null");
        }
        if (intent == null) {
            throw new IllegalArgumentException("intent==null");
        }
        _requestLocationUpdates(provider, null, minTime, minDistance, false, intent);
    }

    /**
     * Registers the current activity to be notified periodically based on
     * the supplied criteria.  Periodically, the supplied PendingIntent will
     * be broadcast with the current Location or with status updates.
     *
     * <p> Location updates are sent with a key of
     * {@link #KEY_LOCATION_CHANGED} and a {@link android.location.Location} value.
     *
     * <p> It may take a while to receive the first location update. If
     * an immediate location is required, applications may use the
     * {@link #getLastKnownLocation(String)} method.
     *
     * <p> The update interval can be controlled using the minTime parameter.
     * The elapsed time between location updates will never be less than
     * minTime, although it can be more depending on the Location Provider
     * implementation and the update interval requested by other applications.
     *
     * <p> Choosing a sensible value for minTime is important to conserve
     * battery life. Each location update requires power from
     * GPS, WIFI, Cell and other radios. Select a minTime value as high as
     * possible while still providing a reasonable user experience.
     * If your application is not in the foreground and showing
     * location to the user then your application should avoid using an active
     * provider (such as {@link #NETWORK_PROVIDER} or {@link #GPS_PROVIDER}),
     * but if you insist then select a minTime of 5 * 60 * 1000 (5 minutes)
     * or greater. If your application is in the foreground and showing
     * location to the user then it is appropriate to select a faster
     * update interval.
     *
     * <p> The minDistance parameter can also be used to control the
     * frequency of location updates. If it is greater than 0 then the
     * location provider will only send your application an update when
     * the location has changed by at least minDistance meters, AND
     * at least minTime milliseconds have passed. However it is more
     * difficult for location providers to save power using the minDistance
     * parameter, so minTime should be the primary tool to conserving battery
     * life.
     *
     * <p> If the provider is disabled by the user, updates will stop,
     * and an intent will be sent with an extra with key
     * {@link #KEY_PROVIDER_ENABLED} and a boolean value of false.
     * If the provider is re-enabled, an intent will be sent with an
     * extra with key {@link #KEY_PROVIDER_ENABLED} and a boolean value of
     * true and location updates will start again.
     *
     * <p> If the provider's status changes, an intent will be sent with
     * an extra with key {@link #KEY_STATUS_CHANGED} and an integer value
     * indicating the new status.  Any extras associated with the status
     * update will be sent as well.
     *
     * <p class="note"> Prior to Jellybean, the minTime parameter was
     * only a hint, and some location provider implementations ignored it.
     * From Jellybean and onwards it is mandatory for Android compatible
     * devices to observe both the minTime and minDistance parameters.
     *
     * @param minTime minimum time interval between location updates, in milliseconds
     * @param minDistance minimum distance between location updates, in meters
     * @param criteria contains parameters for the location manager to choose the
     * appropriate provider and parameters to compute the location
     * @param intent a {#link PendingIntent} to be sent for each location update
     *
     * @throws IllegalArgumentException if criteria is null
     * @throws IllegalArgumentException if intent is null
     * @throws SecurityException if no suitable permission is present for the provider.
     */
    public void requestLocationUpdates(long minTime, float minDistance, Criteria criteria,
            PendingIntent intent) {
        if (criteria == null) {
            throw new IllegalArgumentException("criteria==null");
        }
        if (intent == null) {
            throw new IllegalArgumentException("intent==null");
        }
        _requestLocationUpdates(null, criteria, minTime, minDistance, false, intent);
    }

    private void _requestLocationUpdates(String provider, Criteria criteria,
            long minTime, float minDistance, boolean singleShot, PendingIntent intent) {
        if (minTime < 0L) {
            minTime = 0L;
        }
        if (minDistance < 0.0f) {
            minDistance = 0.0f;
        }

        try {
            mService.requestLocationUpdatesPI(provider, criteria, minTime, minDistance, singleShot, intent);
        } catch (RemoteException ex) {
            Log.e(TAG, "requestLocationUpdates: RemoteException", ex);
        }
    }

    /**
     * Requests a single location update from the named provider.
     *
     * <p> It may take a while to receive the most recent location. If
     * an immediate location is required, applications may use the
     * {@link #getLastKnownLocation(String)} method.
     *
     * <p> In case the provider is disabled by the user, the update will not be received,
     * and the {@link LocationListener#onProviderDisabled(String)}
     * method will be called. As soon as the provider is enabled again,
     * the {@link LocationListener#onProviderEnabled(String)} method will
     * be called and location updates will start again.
     *
     * <p> The supplied Looper is used to implement the callback mechanism.
     *
     * @param provider the name of the provider with which to register
     * @param listener a {#link LocationListener} whose
     * {@link LocationListener#onLocationChanged} method will be called when
     * the location update is available
     * @param looper a Looper object whose message queue will be used to
     * implement the callback mechanism, or null to make callbacks on the
     * main thread
     *
     * @throws IllegalArgumentException if provider is null or doesn't exist
     * @throws IllegalArgumentException if listener is null
     * @throws SecurityException if no suitable permission is present for the provider
     */
    public void requestSingleUpdate(String provider, LocationListener listener, Looper looper) {
        if (provider == null) {
            throw new IllegalArgumentException("provider==null");
        }
        if (listener == null) {
            throw new IllegalArgumentException("listener==null");
        }
        _requestLocationUpdates(provider, null, 0L, 0.0f, true, listener, looper);
    }

    /**
     * Requests a single location update based on the specified criteria.
     *
     * <p> It may take a while to receive the most recent location. If
     * an immediate location is required, applications may use the
     * {@link #getLastKnownLocation(String)} method.
     *
     * <p> In case the provider is disabled by the user, the update will not be received,
     * and the {@link LocationListener#onProviderDisabled(String)}
     * method will be called. As soon as the provider is enabled again,
     * the {@link LocationListener#onProviderEnabled(String)} method will
     * be called and location updates will start again.
     *
     * <p> The supplied Looper is used to implement the callback mechanism.
     *
     * @param criteria contains parameters for the location manager to choose the
     * appropriate provider and parameters to compute the location
     * @param listener a {#link LocationListener} whose
     * {@link LocationListener#onLocationChanged} method will be called when
     * the location update is available
     * @param looper a Looper object whose message queue will be used to
     * implement the callback mechanism, or null to make callbacks on the
     * main thread
     *
     * @throws IllegalArgumentException if criteria is null
     * @throws IllegalArgumentException if listener is null
     * @throws SecurityException if no suitable permission is present to access
     * the location services
     */
    public void requestSingleUpdate(Criteria criteria, LocationListener listener, Looper looper) {
        if (criteria == null) {
            throw new IllegalArgumentException("criteria==null");
        }
        if (listener == null) {
            throw new IllegalArgumentException("listener==null");
        }
        _requestLocationUpdates(null, criteria, 0L, 0.0f, true, listener, looper);
    }

    /**
     * Requests a single location update from the named provider.
     *
     * <p> It may take a while to receive the most recent location. If
     * an immediate location is required, applications may use the
     * {@link #getLastKnownLocation(String)} method.
     *
     * <p> Location updates are sent with a key of
     * {@link #KEY_LOCATION_CHANGED} and a {@link android.location.Location} value.
     *
     * <p> In case the provider is disabled by the user, the update will not be received,
     * and the {@link LocationListener#onProviderDisabled(String)}
     * method will be called. As soon as the provider is enabled again,
     * the {@link LocationListener#onProviderEnabled(String)} method will
     * be called and location updates will start again.
     *
     * @param provider the name of the provider with which to register
     * @param intent a {#link PendingIntent} to be sent for the location update
     *
     * @throws IllegalArgumentException if provider is null or doesn't exist
     * @throws IllegalArgumentException if intent is null
     * @throws SecurityException if no suitable permission is present for the provider
     */
    public void requestSingleUpdate(String provider, PendingIntent intent) {
        if (provider == null) {
            throw new IllegalArgumentException("provider==null");
        }
        if (intent == null) {
            throw new IllegalArgumentException("intent==null");
        }
        _requestLocationUpdates(provider, null, 0L, 0.0f, true, intent);
    }

    /**
     * Requests a single location update based on the specified criteria.
     *
     * <p> It may take a while to receive the most recent location. If
     * an immediate location is required, applications may use the
     * {@link #getLastKnownLocation(String)} method.
     *
     * <p> Location updates are sent with a key of
     * {@link #KEY_LOCATION_CHANGED} and a {@link android.location.Location} value.
     *
     * <p> If the provider is disabled by the user, an update will not be
     * received, and an intent will be sent with an extra with key
     * {@link #KEY_PROVIDER_ENABLED} and a boolean value of false.
     * If the provider is re-enabled, an intent will be sent with an
     * extra with key {@link #KEY_PROVIDER_ENABLED} and a boolean value of
     * true and the location update will occur.
     *
     * @param criteria contains parameters for the location manager to choose the
     * appropriate provider and parameters to compute the location
     * @param intent a {#link PendingIntent} to be sent for the location update
     *
     * @throws IllegalArgumentException if provider is null or doesn't exist
     * @throws IllegalArgumentException if intent is null
     * @throws SecurityException if no suitable permission is present for the provider
     */
    public void requestSingleUpdate(Criteria criteria, PendingIntent intent) {
        if (criteria == null) {
            throw new IllegalArgumentException("criteria==null");
        }
        if (intent == null) {
            throw new IllegalArgumentException("intent==null");
        }
        _requestLocationUpdates(null, criteria, 0L, 0.0f, true, intent);
    }

    /**
     * Removes any current registration for location updates of the current activity
     * with the given LocationListener.  Following this call, updates will no longer
     * occur for this listener.
     *
     * @param listener {#link LocationListener} object that no longer needs location updates
     * @throws IllegalArgumentException if listener is null
     */
    public void removeUpdates(LocationListener listener) {
        if (listener == null) {
            throw new IllegalArgumentException("listener==null");
        }
        if (false) {
            Log.d(TAG, "removeUpdates: listener = " + listener);
        }
        try {
            ListenerTransport transport = mListeners.remove(listener);
            if (transport != null) {
                mService.removeUpdates(transport);
            }
        } catch (RemoteException ex) {
            Log.e(TAG, "removeUpdates: DeadObjectException", ex);
        }
    }

    /**
     * Removes any current registration for location updates of the current activity
     * with the given PendingIntent.  Following this call, updates will no longer
     * occur for this intent.
     *
     * @param intent {#link PendingIntent} object that no longer needs location updates
     * @throws IllegalArgumentException if intent is null
     */
    public void removeUpdates(PendingIntent intent) {
        if (intent == null) {
            throw new IllegalArgumentException("intent==null");
        }
        if (false) {
            Log.d(TAG, "removeUpdates: intent = " + intent);
        }
        try {
            mService.removeUpdatesPI(intent);
        } catch (RemoteException ex) {
            Log.e(TAG, "removeUpdates: RemoteException", ex);
        }
    }

    /**
     * Sets a proximity alert for the location given by the position
     * (latitude, longitude) and the given radius.  When the device
     * detects that it has entered or exited the area surrounding the
     * location, the given PendingIntent will be used to create an Intent
     * to be fired.
     *
     * <p> The fired Intent will have a boolean extra added with key
     * {@link #KEY_PROXIMITY_ENTERING}. If the value is true, the device is
     * entering the proximity region; if false, it is exiting.
     *
     * <p> Due to the approximate nature of position estimation, if the
     * device passes through the given area briefly, it is possible
     * that no Intent will be fired.  Similarly, an Intent could be
     * fired if the device passes very close to the given area but
     * does not actually enter it.
     *
     * <p> After the number of milliseconds given by the expiration
     * parameter, the location manager will delete this proximity
     * alert and no longer monitor it.  A value of -1 indicates that
     * there should be no expiration time.
     *
     * <p> In case the screen goes to sleep, checks for proximity alerts
     * happen only once every 4 minutes. This conserves battery life by
     * ensuring that the device isn't perpetually awake.
     *
     * <p> Internally, this method uses both {@link #NETWORK_PROVIDER}
     * and {@link #GPS_PROVIDER}.
     *
     * @param latitude the latitude of the central point of the
     * alert region
     * @param longitude the longitude of the central point of the
     * alert region
     * @param radius the radius of the central point of the
     * alert region, in meters
     * @param expiration time for this proximity alert, in milliseconds,
     * or -1 to indicate no expiration
     * @param intent a PendingIntent that will be used to generate an Intent to
     * fire when entry to or exit from the alert region is detected
     *
     * @throws SecurityException if no permission exists for the required
     * providers.
     */
    public void addProximityAlert(double latitude, double longitude,
        float radius, long expiration, PendingIntent intent) {
        if (false) {
            Log.d(TAG, "addProximityAlert: latitude = " + latitude +
                ", longitude = " + longitude + ", radius = " + radius +
                ", expiration = " + expiration +
                ", intent = " + intent);
        }
        try {
            mService.addProximityAlert(latitude, longitude, radius, expiration, intent,
                    mContext.getPackageName());
        } catch (RemoteException ex) {
            Log.e(TAG, "addProximityAlert: RemoteException", ex);
        }
    }

    /**
     * Removes the proximity alert with the given PendingIntent.
     *
     * @param intent the PendingIntent that no longer needs to be notified of
     * proximity alerts
     */
    public void removeProximityAlert(PendingIntent intent) {
        if (false) {
            Log.d(TAG, "removeProximityAlert: intent = " + intent);
        }
        try {
            mService.removeProximityAlert(intent);
        } catch (RemoteException ex) {
            Log.e(TAG, "removeProximityAlert: RemoteException", ex);
        }
    }

    /**
     * Returns the current enabled/disabled status of the given provider. If the
     * user has enabled this provider in the Settings menu, true is returned
     * otherwise false is returned
     *
     * @param provider the name of the provider
     * @return true if the provider is enabled
     *
     * @throws SecurityException if no suitable permission is present for the provider.
     * @throws IllegalArgumentException if provider is null
     */
    public boolean isProviderEnabled(String provider) {
        if (provider == null) {
            throw new IllegalArgumentException("provider==null");
        }
        try {
            return mService.isProviderEnabled(provider);
        } catch (RemoteException ex) {
            Log.e(TAG, "isProviderEnabled: RemoteException", ex);
            return false;
        }
    }

    /**
     * Returns a Location indicating the data from the last known
     * location fix obtained from the given provider.  This can be done
     * without starting the provider.  Note that this location could
     * be out-of-date, for example if the device was turned off and
     * moved to another location.
     *
     * <p> If the provider is currently disabled, null is returned.
     *
     * @param provider the name of the provider
     * @return the last known location for the provider, or null
     *
     * @throws SecurityException if no suitable permission is present for the provider.
     * @throws IllegalArgumentException if provider is null or doesn't exist
     */
    public Location getLastKnownLocation(String provider) {
        if (provider == null) {
            throw new IllegalArgumentException("provider==null");
        }
        try {
            return mService.getLastKnownLocation(provider);
        } catch (RemoteException ex) {
            Log.e(TAG, "getLastKnowLocation: RemoteException", ex);
            return null;
        }
    }

    // Mock provider support

    /**
     * Creates a mock location provider and adds it to the set of active providers.
     *
     * @param name the provider name
     * @param requiresNetwork
     * @param requiresSatellite
     * @param requiresCell
     * @param hasMonetaryCost
     * @param supportsAltitude
     * @param supportsSpeed
     * @param supportsBearing
     * @param powerRequirement
     * @param accuracy
     *
     * @throws SecurityException if the ACCESS_MOCK_LOCATION permission is not present
     * or the {@link android.provider.Settings.Secure#ALLOW_MOCK_LOCATION
     * Settings.Secure.ALLOW_MOCK_LOCATION} system setting is not enabled
     * @throws IllegalArgumentException if a provider with the given name already exists
     */
    public void addTestProvider(String name, boolean requiresNetwork, boolean requiresSatellite,
        boolean requiresCell, boolean hasMonetaryCost, boolean supportsAltitude,
        boolean supportsSpeed, boolean supportsBearing, int powerRequirement, int accuracy) {
        try {
            mService.addTestProvider(name, requiresNetwork, requiresSatellite, requiresCell,
                hasMonetaryCost, supportsAltitude, supportsSpeed, supportsBearing, powerRequirement,
                accuracy);
        } catch (RemoteException ex) {
            Log.e(TAG, "addTestProvider: RemoteException", ex);
        }
    }

    /**
     * Removes the mock location provider with the given name.
     *
     * @param provider the provider name
     *
     * @throws SecurityException if the ACCESS_MOCK_LOCATION permission is not present
     * or the {@link android.provider.Settings.Secure#ALLOW_MOCK_LOCATION
     * Settings.Secure.ALLOW_MOCK_LOCATION}} system setting is not enabled
     * @throws IllegalArgumentException if no provider with the given name exists
     */
    public void removeTestProvider(String provider) {
        try {
            mService.removeTestProvider(provider);
        } catch (RemoteException ex) {
            Log.e(TAG, "removeTestProvider: RemoteException", ex);
        }
    }

    /**
     * Sets a mock location for the given provider.
     * <p>This location will be used in place of any actual location from the provider.
     * The location object must have a minimum number of fields set to be
     * considered a valid LocationProvider Location, as per documentation
     * on {@link Location} class.
     *
     * @param provider the provider name
     * @param loc the mock location
     *
     * @throws SecurityException if the ACCESS_MOCK_LOCATION permission is not present
     * or the {@link android.provider.Settings.Secure#ALLOW_MOCK_LOCATION
     * Settings.Secure.ALLOW_MOCK_LOCATION}} system setting is not enabled
     * @throws IllegalArgumentException if no provider with the given name exists
     * @throws IllegalArgumentException if the location is incomplete
     */
    public void setTestProviderLocation(String provider, Location loc) {
        if (!loc.isComplete()) {
            if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN) {
                // for backwards compatibility, allow mock locations that are incomplete
                Log.w(TAG, "Incomplete Location object", new Throwable());
                loc.makeComplete();
            } else {
                throw new IllegalArgumentException(
                        "Location object not complete. Missing timestamps or accuracy?");
            }
        }

        try {
            mService.setTestProviderLocation(provider, loc);
        } catch (RemoteException ex) {
            Log.e(TAG, "setTestProviderLocation: RemoteException", ex);
        }
    }

    /**
     * Removes any mock location associated with the given provider.
     *
     * @param provider the provider name
     *
     * @throws SecurityException if the ACCESS_MOCK_LOCATION permission is not present
     * or the {@link android.provider.Settings.Secure#ALLOW_MOCK_LOCATION
     * Settings.Secure.ALLOW_MOCK_LOCATION}} system setting is not enabled
     * @throws IllegalArgumentException if no provider with the given name exists
     */
    public void clearTestProviderLocation(String provider) {
        try {
            mService.clearTestProviderLocation(provider);
        } catch (RemoteException ex) {
            Log.e(TAG, "clearTestProviderLocation: RemoteException", ex);
        }
    }

    /**
     * Sets a mock enabled value for the given provider.  This value will be used in place
     * of any actual value from the provider.
     *
     * @param provider the provider name
     * @param enabled the mock enabled value
     *
     * @throws SecurityException if the ACCESS_MOCK_LOCATION permission is not present
     * or the {@link android.provider.Settings.Secure#ALLOW_MOCK_LOCATION
     * Settings.Secure.ALLOW_MOCK_LOCATION}} system setting is not enabled
     * @throws IllegalArgumentException if no provider with the given name exists
     */
    public void setTestProviderEnabled(String provider, boolean enabled) {
        try {
            mService.setTestProviderEnabled(provider, enabled);
        } catch (RemoteException ex) {
            Log.e(TAG, "setTestProviderEnabled: RemoteException", ex);
        }
    }

    /**
     * Removes any mock enabled value associated with the given provider.
     *
     * @param provider the provider name
     *
     * @throws SecurityException if the ACCESS_MOCK_LOCATION permission is not present
     * or the {@link android.provider.Settings.Secure#ALLOW_MOCK_LOCATION
     * Settings.Secure.ALLOW_MOCK_LOCATION}} system setting is not enabled
     * @throws IllegalArgumentException if no provider with the given name exists
     */
    public void clearTestProviderEnabled(String provider) {
        try {
            mService.clearTestProviderEnabled(provider);
        } catch (RemoteException ex) {
            Log.e(TAG, "clearTestProviderEnabled: RemoteException", ex);
        }

    }

    /**
     * Sets mock status values for the given provider.  These values will be used in place
     * of any actual values from the provider.
     *
     * @param provider the provider name
     * @param status the mock status
     * @param extras a Bundle containing mock extras
     * @param updateTime the mock update time
     *
     * @throws SecurityException if the ACCESS_MOCK_LOCATION permission is not present
     * or the {@link android.provider.Settings.Secure#ALLOW_MOCK_LOCATION
     * Settings.Secure.ALLOW_MOCK_LOCATION}} system setting is not enabled
     * @throws IllegalArgumentException if no provider with the given name exists
     */
    public void setTestProviderStatus(String provider, int status, Bundle extras, long updateTime) {
        try {
            mService.setTestProviderStatus(provider, status, extras, updateTime);
        } catch (RemoteException ex) {
            Log.e(TAG, "setTestProviderStatus: RemoteException", ex);
        }
    }

    /**
     * Removes any mock status values associated with the given provider.
     *
     * @param provider the provider name
     *
     * @throws SecurityException if the ACCESS_MOCK_LOCATION permission is not present
     * or the {@link android.provider.Settings.Secure#ALLOW_MOCK_LOCATION
     * Settings.Secure.ALLOW_MOCK_LOCATION}} system setting is not enabled
     * @throws IllegalArgumentException if no provider with the given name exists
     */
    public void clearTestProviderStatus(String provider) {
        try {
            mService.clearTestProviderStatus(provider);
        } catch (RemoteException ex) {
            Log.e(TAG, "clearTestProviderStatus: RemoteException", ex);
        }
    }

    // GPS-specific support

    // This class is used to send GPS status events to the client's main thread.
    private class GpsStatusListenerTransport extends IGpsStatusListener.Stub {

        private final GpsStatus.Listener mListener;
        private final GpsStatus.NmeaListener mNmeaListener;

        // This must not equal any of the GpsStatus event IDs
        private static final int NMEA_RECEIVED = 1000;

        private class Nmea {
            long mTimestamp;
            String mNmea;

            Nmea(long timestamp, String nmea) {
                mTimestamp = timestamp;
                mNmea = nmea;
            }
        }
        private ArrayList<Nmea> mNmeaBuffer;

        GpsStatusListenerTransport(GpsStatus.Listener listener) {
            mListener = listener;
            mNmeaListener = null;
        }

        GpsStatusListenerTransport(GpsStatus.NmeaListener listener) {
            mNmeaListener = listener;
            mListener = null;
            mNmeaBuffer = new ArrayList<Nmea>();
        }

        @Override
        public void onGpsStarted() {
            if (mListener != null) {
                Message msg = Message.obtain();
                msg.what = GpsStatus.GPS_EVENT_STARTED;
                mGpsHandler.sendMessage(msg);
            }
        }

        @Override
        public void onGpsStopped() {
            if (mListener != null) {
                Message msg = Message.obtain();
                msg.what = GpsStatus.GPS_EVENT_STOPPED;
                mGpsHandler.sendMessage(msg);
            }
        }

        @Override
        public void onFirstFix(int ttff) {
            if (mListener != null) {
                mGpsStatus.setTimeToFirstFix(ttff);
                Message msg = Message.obtain();
                msg.what = GpsStatus.GPS_EVENT_FIRST_FIX;
                mGpsHandler.sendMessage(msg);
            }
        }

        @Override
        public void onSvStatusChanged(int svCount, int[] prns, float[] snrs,
                float[] elevations, float[] azimuths, int ephemerisMask,
                int almanacMask, int usedInFixMask) {
            if (mListener != null) {
                mGpsStatus.setStatus(svCount, prns, snrs, elevations, azimuths,
                        ephemerisMask, almanacMask, usedInFixMask);

                Message msg = Message.obtain();
                msg.what = GpsStatus.GPS_EVENT_SATELLITE_STATUS;
                // remove any SV status messages already in the queue
                mGpsHandler.removeMessages(GpsStatus.GPS_EVENT_SATELLITE_STATUS);
                mGpsHandler.sendMessage(msg);
            }
        }

        @Override
        public void onNmeaReceived(long timestamp, String nmea) {
            if (mNmeaListener != null) {
                synchronized (mNmeaBuffer) {
                    mNmeaBuffer.add(new Nmea(timestamp, nmea));
                }
                Message msg = Message.obtain();
                msg.what = NMEA_RECEIVED;
                // remove any NMEA_RECEIVED messages already in the queue
                mGpsHandler.removeMessages(NMEA_RECEIVED);
                mGpsHandler.sendMessage(msg);
            }
        }

        private final Handler mGpsHandler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                if (msg.what == NMEA_RECEIVED) {
                    synchronized (mNmeaBuffer) {
                        int length = mNmeaBuffer.size();
                        for (int i = 0; i < length; i++) {
                            Nmea nmea = mNmeaBuffer.get(i);
                            mNmeaListener.onNmeaReceived(nmea.mTimestamp, nmea.mNmea);
                        }
                        mNmeaBuffer.clear();
                    }
                } else {
                    // synchronize on mGpsStatus to ensure the data is copied atomically.
                    synchronized(mGpsStatus) {
                        mListener.onGpsStatusChanged(msg.what);
                    }
                }
            }
        };
    }

    /**
     * Adds a GPS status listener.
     *
     * @param listener GPS status listener object to register
     *
     * @return true if the listener was successfully added
     *
     * @throws SecurityException if the ACCESS_FINE_LOCATION permission is not present
     */
    public boolean addGpsStatusListener(GpsStatus.Listener listener) {
        boolean result;

        if (mGpsStatusListeners.get(listener) != null) {
            // listener is already registered
            return true;
        }
        try {
            GpsStatusListenerTransport transport = new GpsStatusListenerTransport(listener);
            result = mService.addGpsStatusListener(transport);
            if (result) {
                mGpsStatusListeners.put(listener, transport);
            }
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in registerGpsStatusListener: ", e);
            result = false;
        }

        return result;
    }

    /**
     * Removes a GPS status listener.
     *
     * @param listener GPS status listener object to remove
     */
    public void removeGpsStatusListener(GpsStatus.Listener listener) {
        try {
            GpsStatusListenerTransport transport = mGpsStatusListeners.remove(listener);
            if (transport != null) {
                mService.removeGpsStatusListener(transport);
            }
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in unregisterGpsStatusListener: ", e);
        }
    }

    /**
     * Adds an NMEA listener.
     *
     * @param listener a {#link GpsStatus.NmeaListener} object to register
     *
     * @return true if the listener was successfully added
     *
     * @throws SecurityException if the ACCESS_FINE_LOCATION permission is not present
     */
    public boolean addNmeaListener(GpsStatus.NmeaListener listener) {
        boolean result;

        if (mNmeaListeners.get(listener) != null) {
            // listener is already registered
            return true;
        }
        try {
            GpsStatusListenerTransport transport = new GpsStatusListenerTransport(listener);
            result = mService.addGpsStatusListener(transport);
            if (result) {
                mNmeaListeners.put(listener, transport);
            }
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in registerGpsStatusListener: ", e);
            result = false;
        }

        return result;
    }

    /**
     * Removes an NMEA listener.
     *
     * @param listener a {#link GpsStatus.NmeaListener} object to remove
     */
    public void removeNmeaListener(GpsStatus.NmeaListener listener) {
        try {
            GpsStatusListenerTransport transport = mNmeaListeners.remove(listener);
            if (transport != null) {
                mService.removeGpsStatusListener(transport);
            }
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in unregisterGpsStatusListener: ", e);
        }
    }

     /**
     * Retrieves information about the current status of the GPS engine.
     * This should only be called from the {@link GpsStatus.Listener#onGpsStatusChanged}
     * callback to ensure that the data is copied atomically.
     *
     * The caller may either pass in a {@link GpsStatus} object to set with the latest
     * status information, or pass null to create a new {@link GpsStatus} object.
     *
     * @param status object containing GPS status details, or null.
     * @return status object containing updated GPS status.
     */
    public GpsStatus getGpsStatus(GpsStatus status) {
        if (status == null) {
            status = new GpsStatus();
       }
       status.setStatus(mGpsStatus);
       return status;
    }

    /**
     * Sends additional commands to a location provider.
     * Can be used to support provider specific extensions to the Location Manager API
     *
     * @param provider name of the location provider.
     * @param command name of the command to send to the provider.
     * @param extras optional arguments for the command (or null).
     * The provider may optionally fill the extras Bundle with results from the command.
     *
     * @return true if the command succeeds.
     */
    public boolean sendExtraCommand(String provider, String command, Bundle extras) {
        try {
            return mService.sendExtraCommand(provider, command, extras);
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in sendExtraCommand: ", e);
            return false;
        }
    }

    /**
     * Used by NetInitiatedActivity to report user response
     * for network initiated GPS fix requests.
     *
     * {@hide}
     */
    public boolean sendNiResponse(int notifId, int userResponse) {
    	try {
            return mService.sendNiResponse(notifId, userResponse);
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in sendNiResponse: ", e);
            return false;
        }
    }

}