Examples for the presentation "A Practical Introduction to Sensing with Android" in the Context-Aware Computing course, Department of Computer Science, Aarhus University, 2013

AccelerometerActivity.java

package dk.au.cs.ubi.cac.one;

import android.app.Activity;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.util.Log;

public class AccelerometerActivity extends Activity {
	
	private static final String TAG = AccelerometerActivity.class.getSimpleName();

	private SensorManager sensorManager;
	private final SensorEventListener accelerometerSensorEventListener = new AccelerometerSensorEventListener();

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_accelerometer);

		sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
	}

	@Override
	protected void onResume() {
		Sensor accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
		if (!sensorManager.registerListener(accelerometerSensorEventListener, accelerometer, SensorManager.SENSOR_DELAY_FASTEST)) {
			Log.w(TAG, "Couldn't register accelerometer.");
		}
	}

	@Override
	protected void onPause() {
		sensorManager.unregisterListener(accelerometerSensorEventListener);
	}

	private static final class AccelerometerSensorEventListener implements SensorEventListener {

		@Override
		public void onAccuracyChanged(Sensor sensor, int accuracy) {
			// Do something when the accuracy has changed
		}

		@Override
		public void onSensorChanged(SensorEvent event) {
			// Do something with your event
		}

	}
}

GpsActivity.java

package dk.au.cs.ubi.cac.one;

import android.app.Activity;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;

public class GpsActivity extends Activity {

	private LocationManager locationManager;
	private final LocationListener gpsLocationListener = new GpsLocationListener();

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_gps);

		locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
	}

	@Override
	protected void onResume() {
		locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, gpsLocationListener);
	}

	@Override
	protected void onPause() {
		locationManager.removeUpdates(gpsLocationListener);
	}

	private static final class GpsLocationListener implements LocationListener {

		@Override
		public void onLocationChanged(Location location) {
			// Do something with the received location object
		}

		@Override
		public void onProviderDisabled(String provider) {
			// Handle that the provider got disabled
		}

		@Override
		public void onProviderEnabled(String provider) {
			// Handle that the provider got enabled
		}

		@Override
		public void onStatusChanged(String provider, int status, Bundle extras) {
			// Handle the status change
		}

	}
}

WifiActivity.java

package dk.au.cs.ubi.cac.one;

import java.util.List;
import java.util.concurrent.TimeUnit;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.wifi.ScanResult;
import android.net.wifi.WifiManager;
import android.net.wifi.WifiManager.WifiLock;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;

public class WifiActivity extends Activity {

	private static final String TAG = WifiActivity.class.getSimpleName();

	private static final long WIFI_SCAN_DELAY_MILLIS = TimeUnit.SECONDS.toMillis(1);

	private WifiManager wifiManager;
	private WifiScanBroadcastReceiver wifiScanBroadcastReceiver = new WifiScanBroadcastReceiver();
	private WifiLock wifiLock;

	private volatile boolean running;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_wifi);

		wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
		wifiLock = wifiManager.createWifiLock(WifiManager.WIFI_MODE_SCAN_ONLY, WifiActivity.class.getName());
	}

	@Override
	protected void onResume() {
		running = true;

		wifiLock.acquire();

		registerReceiver(wifiScanBroadcastReceiver, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));

		final Handler wifiScanHandler = new Handler();
		Runnable wifiScanRunnable = new Runnable() {

			@Override
			public void run() {
				if (!running) {
					return;
				}

				if (!wifiManager.startScan()) {
					Log.w(TAG, "Couldn't start Wi-fi scan!");
				}

				wifiScanHandler.postDelayed(this, WIFI_SCAN_DELAY_MILLIS);
			}

		};
		wifiScanHandler.post(wifiScanRunnable);
	}

	@Override
	protected void onPause() {
		running = false;

		unregisterReceiver(wifiScanBroadcastReceiver);

		wifiLock.release();
	}

	private final class WifiScanBroadcastReceiver extends BroadcastReceiver {

		@Override
		public void onReceive(Context context, Intent intent) {
			if (!running || !WifiManager.SCAN_RESULTS_AVAILABLE_ACTION.equals(intent.getAction())) {
				return;
			}

			List<ScanResult> scanResults = wifiManager.getScanResults();

			// Do something with your scanResults
		}

	}

}