Retrieves best known location from all location providers available on this system. - Android Map

Android examples for Map:Location Provider

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Description

Retrieves best known location from all location providers available on this system.

Demo Code


//package com.java2s;
import android.content.Context;
import android.location.Location;
import android.location.LocationManager;

public class Main {
    private static final int THRESHOLD_ACCURACY = 200;
    private static final int TWO_MINUTES = 1000 * 60 * 2;

    public static Location getBestKnownLocation(final Context context) {
        return getBestKnownLocation((LocationManager) context
                .getSystemService(Context.LOCATION_SERVICE));
    }/*from  ww w .  j  av  a2s . c  o  m*/

    /**
     * Retrieves best known location from all location providers available on
     * this system.
     * 
     * @param locationManager
     *            A {@link LocationManager}
     * @return Last known location or <code>null</code> if it could not be
     *         found.
     */
    public static Location getBestKnownLocation(
            final LocationManager locationManager) {
        Location bestLocation = null;

        for (final String provider : locationManager.getProviders(false)) {
            final Location location = locationManager
                    .getLastKnownLocation(provider);

            if ((location != null)
                    && isBetterLocation(location, bestLocation)) {
                bestLocation = location;
            }
        }

        return bestLocation;
    }

    /**
     * Determines the best {@link Location}.
     * 
     * @param location
     *            The new Location that you want to evaluate
     * @param currentBestLocation
     *            The current Location fix, to which you want to compare the new
     *            one
     * @return <code>true</code> if <code>location</code> is a better location,
     *         <code>false</code> otherwise.
     */
    public static boolean isBetterLocation(final Location location,
            final Location currentBestLocation) {

        if (currentBestLocation == null)
            return true;

        final boolean isFromSameProvider = isSameProvider(
                location.getProvider(), currentBestLocation.getProvider());
        final float accuracyDelta = (location.getAccuracy() - currentBestLocation
                .getAccuracy());
        final boolean isLessAccurate = accuracyDelta > 0;
        final boolean isMoreAccurate = accuracyDelta < 0;
        final boolean isSignificantlyLessAccurate = accuracyDelta > THRESHOLD_ACCURACY;

        final long timeDelta = location.getTime()
                - currentBestLocation.getTime();
        final boolean isSignificantlyNewer = timeDelta > TWO_MINUTES;
        final boolean isSignificantlyOlder = timeDelta < -TWO_MINUTES;
        final boolean isNewer = timeDelta > 0;

        if (isSignificantlyNewer)
            return true;
        else if (isSignificantlyOlder)
            return false;

        if (isMoreAccurate)
            return true;
        else if (isNewer && !isLessAccurate)
            return true;
        else if (isNewer && !isSignificantlyLessAccurate
                && isFromSameProvider)
            return true;

        return false;
    }

    private static boolean isSameProvider(final String provider1,
            final String provider2) {
        if (provider1 == null)
            return provider2 == null;

        return provider1.equals(provider2);
    }
}

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