LocationGetLocationActivity.java

package course.examples.Location.GetLocation;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import android.app.Activity;
import android.content.Context;
import android.graphics.Color;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

public class LocationGetLocationActivity extends Activity {

	private static final long ONE_MIN = 1000 * 60;
	private static final long TWO_MIN = ONE_MIN * 2;
	private static final long FIVE_MIN = ONE_MIN * 5;
	private static final long MEASURE_TIME = 1000 * 30;
	private static final long POLLING_FREQ = 1000 * 10;
	private static final float MIN_ACCURACY = 25.0f;
	private static final float MIN_LAST_READ_ACCURACY = 500.0f;
	private static final float MIN_DISTANCE = 10.0f;

	// Views for display location information
	private TextView mAccuracyView;
	private TextView mTimeView;
	private TextView mLatView;
	private TextView mLngView;

	private int mTextViewColor = Color.GRAY;

	// Current best location estimate
	private Location mBestReading;

	// Reference to the LocationManager and LocationListener
	private LocationManager mLocationManager;
	private LocationListener mLocationListener;

	private final String TAG = "LocationGetLocationActivity";

	private boolean mFirstUpdate = true;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);

		setContentView(R.layout.main);

		mAccuracyView = (TextView) findViewById(R.id.accuracy_view);
		mTimeView = (TextView) findViewById(R.id.time_view);
		mLatView = (TextView) findViewById(R.id.lat_view);
		mLngView = (TextView) findViewById(R.id.lng_view);

		// Acquire reference to the LocationManager
		if (null == (mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE)))
			finish();

		// Get best last location measurement
		mBestReading = bestLastKnownLocation(MIN_LAST_READ_ACCURACY, FIVE_MIN);

		// Display last reading information
		if (null != mBestReading) {

			updateDisplay(mBestReading);

		} else {

			mAccuracyView.setText("No Initial Reading Available");

		}

		mLocationListener = new LocationListener() {

			// Called back when location changes

			public void onLocationChanged(Location location) {

				ensureColor();

				// Determine whether new location is better than current best
				// estimate

				if (null == mBestReading
						|| location.getAccuracy() < mBestReading.getAccuracy()) {

					// Update best estimate
					mBestReading = location;

					// Update display
					updateDisplay(location);

					if (mBestReading.getAccuracy() < MIN_ACCURACY)
						mLocationManager.removeUpdates(mLocationListener);

				}
			}

			public void onStatusChanged(String provider, int status,
					Bundle extras) {
				// NA
			}

			public void onProviderEnabled(String provider) {
				// NA
			}

			public void onProviderDisabled(String provider) {
				// NA
			}
		};
	}

	@Override
	protected void onResume() {
		super.onResume();

		// Determine whether initial reading is
		// "good enough". If not, register for
		// further location updates

		if (null == mBestReading
				|| mBestReading.getAccuracy() > MIN_LAST_READ_ACCURACY
				|| mBestReading.getTime() < System.currentTimeMillis()
						- TWO_MIN) {

			// Register for network location updates
			if (null != mLocationManager
					.getProvider(LocationManager.NETWORK_PROVIDER)) {
				mLocationManager.requestLocationUpdates(
						LocationManager.NETWORK_PROVIDER, POLLING_FREQ,
						MIN_DISTANCE, mLocationListener);
			}

			// Register for GPS location updates
			if (null != mLocationManager
					.getProvider(LocationManager.GPS_PROVIDER)) {
				mLocationManager.requestLocationUpdates(
						LocationManager.GPS_PROVIDER, POLLING_FREQ,
						MIN_DISTANCE, mLocationListener);
			}
			
			// Schedule a runnable to unregister location listeners
			Executors.newScheduledThreadPool(1).schedule(new Runnable() {

				@Override
				public void run() {

					Log.i(TAG, "location updates cancelled");

					mLocationManager.removeUpdates(mLocationListener);

				}
			}, MEASURE_TIME, TimeUnit.MILLISECONDS);
		}
	}

	// Unregister location listeners
	@Override
	protected void onPause() {
		super.onPause();

		mLocationManager.removeUpdates(mLocationListener);

	}

	// Get the last known location from all providers
	// return best reading that is as accurate as minAccuracy and
	// was taken no longer then minAge milliseconds ago. If none,
	// return null.

	private Location bestLastKnownLocation(float minAccuracy, long maxAge) {

		Location bestResult = null;
		float bestAccuracy = Float.MAX_VALUE;
		long bestAge = Long.MIN_VALUE;

		List<String> matchingProviders = mLocationManager.getAllProviders();

		for (String provider : matchingProviders) {

			Location location = mLocationManager.getLastKnownLocation(provider);

			if (location != null) {

				float accuracy = location.getAccuracy();
				long time = location.getTime();

				if (accuracy < bestAccuracy) {

					bestResult = location;
					bestAccuracy = accuracy;
					bestAge = time;

				}
			}
		}

		// Return best reading or null
		if (bestAccuracy > minAccuracy
				|| (System.currentTimeMillis() - bestAge) > maxAge) {
			return null;
		} else {
			return bestResult;
		}
	}

	// Update display
	private void updateDisplay(Location location) {

		mAccuracyView.setText("Accuracy:" + location.getAccuracy());

		mTimeView.setText("Time:"
				+ new SimpleDateFormat("MM/dd/yyyy HH:mm:ss", Locale
						.getDefault()).format(new Date(location.getTime())));

		mLatView.setText("Longitude:" + location.getLongitude());

		mLngView.setText("Latitude:" + location.getLatitude());

	}

	private void ensureColor() {
		if (mFirstUpdate) {
			setTextViewColor(mTextViewColor);
			mFirstUpdate = false;
		}
	}

	private void setTextViewColor(int color) {

		mAccuracyView.setTextColor(color);
		mTimeView.setTextColor(color);
		mLatView.setTextColor(color);
		mLngView.setTextColor(color);

	}

}