Sensor Fun: Location Based Services and GPS for Android

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
	package="com.hascode.android.location_app" android:versionCode="1"
	android:versionName="1.0">
	<application android:icon="@drawable/icon" android:label="@string/app_name">
		<activity android:name=".LocationActivity" android:label="@string/app_name">
			<intent-filter>
				<action android:name="android.intent.action.MAIN" />
				<category android:name="android.intent.category.LAUNCHER" />
			</intent-filter>
		</activity>

	</application>
	<uses-sdk android:minSdkVersion="7" />

	<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"></uses-permission>
	<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission>
	<uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS"></uses-permission>
	<uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION"></uses-permission>
</manifest>

<?xml version="1.0" encoding="utf-8"?>
<TableLayout android:layout_width="fill_parent"
	android:layout_height="fill_parent" android:orientation="vertical"
	xmlns:android="http://schemas.android.com/apk/res/android">
	<TextView android:id="@+id/output" android:layout_width="wrap_content"
		android:layout_height="wrap_content" android:text="@string/loading">
	</TextView>
	<Button android:id="@+id/btShowProviders" android:layout_width="wrap_content"
		android:layout_height="wrap_content" android:text="@string/showProviders">
	</Button>
	<Button android:id="@+id/btShowLocation" android:layout_width="wrap_content"
		android:layout_height="wrap_content" android:text="@string/showLocation">
	</Button>
</TableLayout>

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <string name="app_name">LocationApp</string>
 <string name="loading">loading...</string>
 <string name="showProviders">Show available providers</string>
 <string name="showLocation">Listen to coordinate updates</string>
</resources>

package com.hascode.android.location_app;

import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class LocationActivity extends Activity implements LocationListener {
	// attrs
	private static final String TAG = "com.hascode.android.location-app";
	private LocationManager locationManager;
	private static final String PROVIDER = "gps"; // for this tutorial we simply
	// assume that this provider
	// exists

	// ui elements
	private TextView output;
	private Button btShowProviders;
	private Button btShowLocation;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		output = (TextView) findViewById(R.id.output);
		btShowProviders = (Button) findViewById(R.id.btShowProviders);
		btShowLocation = (Button) findViewById(R.id.btShowLocation);

		locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
		if (locationManager == null) {
			Log.w(TAG, "no location manager found");
			output.setText("no location manager no fun ..");
		} else {
			btShowProviders.setOnClickListener(new View.OnClickListener() {
				@Override
				public void onClick(View view) {
					showProviders();
				}
			});

			btShowLocation.setOnClickListener(new View.OnClickListener() {
				@Override
				public void onClick(View view) {
					showLocation();
				}
			});
		}
	}

	/**
	 * shows the list of available location providers
	 */
	private void showProviders() {
		List<String> providers = locationManager.getAllProviders();
		Log.d(TAG, "available providers found: " + providers.size());
		StringBuilder s = new StringBuilder();
		for (String provider : providers) {
			s.append(provider);
			s.append("\n");
		}
		output.setText(s.toString());
	}

	/**
	 * displays the current location using the gps provider
	 */
	private void showLocation() {
		LocationProvider gps = locationManager.getProvider(PROVIDER);
		if (gps == null) {
			Log.w(TAG, "gps provider not found");
			return;
		}

		locationManager.requestLocationUpdates(PROVIDER, 1200, 5, this);
		Log.d(TAG, "listening to gps events started");
	}

	/*
	 * (non-Javadoc)
	 *
	 * @see
	 * android.location.LocationListener#onLocationChanged(android.location.
	 * Location)
	 */
	@Override
	public void onLocationChanged(Location location) {
		String result = String.format(
				"Your coords: latitude %f is longitude is %f", location
						.getLatitude(), location.getLongitude());
		Log.d(TAG, "location update received: " + result);
		output.setText(result);
	}

	/*
	 * (non-Javadoc)
	 *
	 * @see
	 * android.location.LocationListener#onProviderDisabled(java.lang.String)
	 */
	@Override
	public void onProviderDisabled(String provider) {
		Log.d(TAG, "the following provider was disabled: " + provider);
	}

	/*
	 * (non-Javadoc)
	 *
	 * @see
	 * android.location.LocationListener#onProviderEnabled(java.lang.String)
	 */
	@Override
	public void onProviderEnabled(String provider) {
		Log.d(TAG, "the following provider was enabled: " + provider);
	}

	/*
	 * (non-Javadoc)
	 *
	 * @see android.location.LocationListener#onStatusChanged(java.lang.String,
	 * int, android.os.Bundle)
	 */
	@Override
	public void onStatusChanged(String provider, int status, Bundle extras) {
		Log.d(TAG, String.format(
				"Provider status has changed. provider: %s, status: %d",
				provider, status));
	}
}