1. Mobile Programming Lecture 9 Bound Service, Location, Sensors, IntentFilter

2. Agenda Bound Services Location Sensor Starting an Activity for a Result Understanding Implicit Intents

3. Bound Service When you create a Bound Service, you must provide an IBinder that provides the programming interface that clients can use to interact with the Service There are 3 ways that you can provide this interface: 1. Extending the Binder class 2. Using a Messenger 3. Using AIDL

4. Bound Service

5. Bound Service - 1 extending Binder this is the preferred technique when your service is merely a background worker for your own application the only reason you would not create your interface this way is because your service is used by other applications or across separate processes

6. Bound Service - 1 extending Binder Here's how to set it up 1.In your service, create an instance of Binder that returns the current Service instance, which has public methods the client can callBinderService 2.Return this instance of Binder from the onBind() callback methodBinderonBind() 3.In the client, receive the Binder from the onServiceConnected() callback method and make calls to the bound service using the methods providedBinder onServiceConnected()

7. Bound Service - 1 extending Binder see BoundServiceBinderExample.tar ServiceConnection class monitors the connection between the client and the Service When a Service is bound, the binder returned is returned to the onServiceConnected() method of ServiceConnection

8. Bound Service - 2 using Messenger if you need your interface to work across different processes, you can create an interface for the service with a Messenger the service defines a Handler that responds to different types of Message objects Additionally, the client can define a Messenger of its own so the service can send messages back. this is the simplest way to perform interprocess communication (IPC).

9. Bound Service - 2 using Messenger Notice that the handleMessage() method in the Handler is where the service receives the incoming Message and decides what to do, based on the what member.handleMessage()HandlerMessagewhat

10. Bound Service - 2 using Messenger see BoundServiceMessengerExample.tar

11. Bound Service - 3 using the AIDL Using AIDL is confusing AIDL isn't used that often We won't cover this

12. Location Providers To obtain user location, you can use GPS o most accurate o but  consumes battery power fast  takes a while to determine location Network Location Provider

13. Location - LocationManager Requesting Location Updates To get the user location, you need to use the LocationManager, which is a system service This returns a Location object, which can tell you o latitude o longitude o distance between two locations (comparing to another Location object) o accuracy of the Location in meters o direction of travel in degrees o speed of travel in meters per second The Location, however, does not give you any human readable address such as street name, state, or country

14. Requesting Location Updates You can use the Location object to obtain a human-readable address by using a Geocoder Geocoder can give you a list of addresses (since it may not always be sure because of accuracy issues) o returns a List of Address objects, i.e. List  street name  city  state  country  zip code Location - Geocoder and Address

15. Location - Last Known Location Requesting Location Updates Since GPS and Wifi location are not quite instantaeous, you can get the last known location until one of them becomes available

16. Location - Last Known Location final LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); getButton = (Button) findViewById(R.id.button1); tv = (TextView) findViewById(R.id.textView1); getButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Location lastLoc = lm.getLastKnownLocation( LocationManager.NETWORK_PROVIDER); Geocoder geo = new Geocoder(getApplicationContext()); List addresses; addresses = geo.getFromLocation(lastLoc.getLatitude(), lastLoc.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); } });

17. Location - Last Known Location final LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); getButton = (Button) findViewById(R.id.button1); tv = (TextView) findViewById(R.id.textView1); getButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Location lastLoc = lm.getLastKnownLocation( LocationManager.NETWORK_PROVIDER); Geocoder geo = new Geocoder(getApplicationContext()); List addresses; addresses = geo.getFromLocation(lastLoc.getLatitude(), lastLoc.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); } }); Similar to getting the system service for the DownloadManager

18. Location - Last Known Location final LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); getButton = (Button) findViewById(R.id.button1); tv = (TextView) findViewById(R.id.textView1); getButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Location lastLoc = lm.getLastKnownLocation( LocationManager.NETWORK_PROVIDER); Geocoder geo = new Geocoder(getApplicationContext()); List addresses; addresses = geo.getFromLocation(lastLoc.getLatitude(), lastLoc.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); } }); What was the last known location?

19. Location - Last Known Location final LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); getButton = (Button) findViewById(R.id.button1); tv = (TextView) findViewById(R.id.textView1); getButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Location lastLoc = lm.getLastKnownLocation( LocationManager.NETWORK_PROVIDER); Geocoder geo = new Geocoder(getApplicationContext()); List addresses; addresses = geo.getFromLocation(lastLoc.getLatitude(), lastLoc.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); } }); We need to use Geocoder to transform longitude and latitude to an address

20. Location - Last Known Location final LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); getButton = (Button) findViewById(R.id.button1); tv = (TextView) findViewById(R.id.textView1); getButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Location lastLoc = lm.getLastKnownLocation( LocationManager.NETWORK_PROVIDER); Geocoder geo = new Geocoder(getApplicationContext()); List addresses; addresses = geo.getFromLocation(lastLoc.getLatitude(), lastLoc.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); } }); We will store address here

21. Location - Last Known Location final LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); getButton = (Button) findViewById(R.id.button1); tv = (TextView) findViewById(R.id.textView1); getButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Location lastLoc = lm.getLastKnownLocation( LocationManager.NETWORK_PROVIDER); Geocoder geo = new Geocoder(getApplicationContext()); List addresses; addresses = geo.getFromLocation(lastLoc.getLatitude(), lastLoc.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); } }); Let's get a List of Addresses (although there may be only 1 sometimes)

22. Location - Last Known Location final LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); getButton = (Button) findViewById(R.id.button1); tv = (TextView) findViewById(R.id.textView1); getButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Location lastLoc = lm.getLastKnownLocation( LocationManager.NETWORK_PROVIDER); Geocoder geo = new Geocoder(getApplicationContext()); List addresses; addresses = geo.getFromLocation(lastLoc.getLatitude(), lastLoc.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); } }); Pass the latitude...

23. Location - Last Known Location final LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); getButton = (Button) findViewById(R.id.button1); tv = (TextView) findViewById(R.id.textView1); getButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Location lastLoc = lm.getLastKnownLocation( LocationManager.NETWORK_PROVIDER); Geocoder geo = new Geocoder(getApplicationContext()); List addresses; addresses = geo.getFromLocation(lastLoc.getLatitude(), lastLoc.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); } }); the longitude...

24. Location - Last Known Location final LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); getButton = (Button) findViewById(R.id.button1); tv = (TextView) findViewById(R.id.textView1); getButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Location lastLoc = lm.getLastKnownLocation( LocationManager.NETWORK_PROVIDER); Geocoder geo = new Geocoder(getApplicationContext()); List addresses; addresses = geo.getFromLocation(lastLoc.getLatitude(), lastLoc.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); } }); and the max number of addresses that you want to be returned

25. Location - Last Known Location final LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); getButton = (Button) findViewById(R.id.button1); tv = (TextView) findViewById(R.id.textView1); getButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Location lastLoc = lm.getLastKnownLocation( LocationManager.NETWORK_PROVIDER); Geocoder geo = new Geocoder(getApplicationContext()); List addresses; addresses = geo.getFromLocation(lastLoc.getLatitude(), lastLoc.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); } }); Get the first line of the first address in the list

26. Location - Last Known Location See LastKnownLocationExample.tar

27. Location - Location Updates Requesting Location Updates To get actual location updates periodically, you should use a LocationListener At some point, you should stop requesting location updates, possibly when o Activity loses focus o You no longer need the location

28. Location - Location Updates final LocationManager lm = (LocationManager) getSystemService(LOCATION_SERVICE); final LocationListener ll = new LocationListener() { @Override public void onStatusChanged(String provider, int status, Bundle extras) {} @Override public void onProviderEnabled(String provider) {} @Override public void onProviderDisabled(String provider) {} @Override public void onLocationChanged(Location location) { Geocoder geo = new Geocoder(getApplicationContext()); List addresses = null; addresses = geo.getFromLocation(location.getLatitude(), location.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); lm.removeUpdates(this); } };

29. Location - Location Updates final LocationManager lm = (LocationManager) getSystemService(LOCATION_SERVICE); final LocationListener ll = new LocationListener() { @Override public void onStatusChanged(String provider, int status, Bundle extras) {} @Override public void onProviderEnabled(String provider) {} @Override public void onProviderDisabled(String provider) {} @Override public void onLocationChanged(Location location) { Geocoder geo = new Geocoder(getApplicationContext()); List addresses = null; addresses = geo.getFromLocation(location.getLatitude(), location.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); lm.removeUpdates(this); } }; We need to register a LocationListener if we want to get updates on the location periodically

30. Location - Location Updates final LocationManager lm = (LocationManager) getSystemService(LOCATION_SERVICE); final LocationListener ll = new LocationListener() { @Override public void onStatusChanged(String provider, int status, Bundle extras) {} @Override public void onProviderEnabled(String provider) {} @Override public void onProviderDisabled(String provider) {} @Override public void onLocationChanged(Location location) { Geocoder geo = new Geocoder(getApplicationContext()); List addresses = null; addresses = geo.getFromLocation(location.getLatitude(), location.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); lm.removeUpdates(this); } }; We're forced to override these methods, although we don't use them

31. Location - Location Updates final LocationManager lm = (LocationManager) getSystemService(LOCATION_SERVICE); final LocationListener ll = new LocationListener() { @Override public void onStatusChanged(String provider, int status, Bundle extras) {} @Override public void onProviderEnabled(String provider) {} @Override public void onProviderDisabled(String provider) {} @Override public void onLocationChanged(Location location) { Geocoder geo = new Geocoder(getApplicationContext()); List addresses = null; addresses = geo.getFromLocation(location.getLatitude(), location.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); lm.removeUpdates(this); } }; In this callback method is where you code your response to a location change

32. Location - Location Updates final LocationManager lm = (LocationManager) getSystemService(LOCATION_SERVICE); final LocationListener ll = new LocationListener() { @Override public void onStatusChanged(String provider, int status, Bundle extras) {} @Override public void onProviderEnabled(String provider) {} @Override public void onProviderDisabled(String provider) {} @Override public void onLocationChanged(Location location) { Geocoder geo = new Geocoder(getApplicationContext()); List addresses = null; addresses = geo.getFromLocation(location.getLatitude(), location.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); lm.removeUpdates(this); } }; Nothing new here...

33. Location - Location Updates final LocationManager lm = (LocationManager) getSystemService(LOCATION_SERVICE); final LocationListener ll = new LocationListener() { @Override public void onStatusChanged(String provider, int status, Bundle extras) {} @Override public void onProviderEnabled(String provider) {} @Override public void onProviderDisabled(String provider) {} @Override public void onLocationChanged(Location location) { Geocoder geo = new Geocoder(getApplicationContext()); List addresses = null; addresses = geo.getFromLocation(location.getLatitude(), location.getLongitude(), 1); if(addresses != null) tv.setText(addresses.get(0).getAddressLine(0)); lm.removeUpdates(this); } }; Let's save battery life and stop listening for updates, although you may choose to stop listening for updates at some other point if you want to

34. Location - Location Updates See LocationManagerExample.tar

35. Location - Permissions In order to receive location updates from NETWORK_PROVIDER or GPS_PROVIDER, you must request user permission by declaring one or both of the following permissions o ACCESS_COARSE_LOCATION  (Wifi location) o ACCESS_FINE_LOCATION  (GPS location)

36. Location - Mock Location You can test your location-based features by mocking location data in the Emulator http://developer.android.com/guide/topics/location/obtaining -user-location.html#MockData The Emulator uses the GPS provider Found under the Emulator Control View in DDMS, under the Telephony View

37. Accellerometer (Motion Sensor) Gyroscope (Motion Sensor) Light (Environment Sensor) Proximity: how close the face of a device is to an object Pressure and more See SensorListExample.tar Sensor

38. SensorManager lets you access the device's sensors. Get an instance of this class by calling Context.getSystemService(SENSOR_SERVICE). Always make sure to disable sensors you don't need, especially when your activity is paused o failing to do so can drain the battery in just a few hours o the system will not disable sensors automatically when the screen turns off. SensorManager

39. The values for each sensor may change at some point Set up an Event Listener to take action when these change These values can be retrieved from a float values[] array, regardless of the type of Sensor SensorEvent

40. public class SensorExampleActivity extends Activity implements SensorEventListener { SensorManager mSensorManager; Sensor mProximity; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); mProximity = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY); }... } SensorEvent

41. public class SensorExampleActivity extends Activity implements SensorEventListener { SensorManager mSensorManager; Sensor mProximity; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); mProximity = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY); }... } SensorEvent Because we want to know when there's a SensorEvent, when values of the Sensor change

42. public class SensorExampleActivity extends Activity implements SensorEventListener { SensorManager mSensorManager; Sensor mProximity; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); mProximity = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY); }... } SensorEvent Similar to how we got the Location service

43. public class SensorExampleActivity extends Activity implements SensorEventListener { SensorManager mSensorManager; Sensor mProximity; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); mProximity = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY); }... } SensorEvent Let's get a Sensor

44. public class SensorExampleActivity extends Activity implements SensorEventListener { SensorManager mSensorManager; Sensor mProximity; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); mProximity = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY); }... } SensorEvent The Proximity Sensor specifically

45. public class SensorExampleActivity extends Activity implements SensorEventListener { SensorManager mSensorManager; Sensor mProximity; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); mProximity = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY); }... } SensorEvent The rest of the code for this class on the next slide

46. public class SensorExampleActivity extends Activity implements SensorEventListener {... protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL); } protected void onPause() { super.onPause(); mSensorManager.unregisterListener(this); } public void onSensorChanged(SensorEvent event) { Toast.makeText(this, "Proximity = " + event.values[0], Toast.LENGTH_SHORT).show(); } SensorEvent onCreate() is here somewhere, on the previous page

47. public class SensorExampleActivity extends Activity implements SensorEventListener {... protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL); } protected void onPause() { super.onPause(); mSensorManager.unregisterListener(this); } public void onSensorChanged(SensorEvent event) { Toast.makeText(this, "Proximity = " + event.values[0], Toast.LENGTH_SHORT).show(); } SensorEvent Note that this is onResume()

48. public class SensorExampleActivity extends Activity implements SensorEventListener {... protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL); } protected void onPause() { super.onPause(); mSensorManager.unregisterListener(this); } public void onSensorChanged(SensorEvent event) { Toast.makeText(this, "Proximity = " + event.values[0], Toast.LENGTH_SHORT).show(); } SensorEvent We only want to listen when the Activity is visible in this case, so we do this in onResume()

49. public class SensorExampleActivity extends Activity implements SensorEventListener {... protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL); } protected void onPause() { super.onPause(); mSensorManager.unregisterListener(this); } public void onSensorChanged(SensorEvent event) { Toast.makeText(this, "Proximity = " + event.values[0], Toast.LENGTH_SHORT).show(); } SensorEvent We pass a Context...

50. public class SensorExampleActivity extends Activity implements SensorEventListener {... protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL); } protected void onPause() { super.onPause(); mSensorManager.unregisterListener(this); } public void onSensorChanged(SensorEvent event) { Toast.makeText(this, "Proximity = " + event.values[0], Toast.LENGTH_SHORT).show(); } SensorEvent a Sensor...

51. public class SensorExampleActivity extends Activity implements SensorEventListener {... protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL); } protected void onPause() { super.onPause(); mSensorManager.unregisterListener(this); } public void onSensorChanged(SensorEvent event) { Toast.makeText(this, "Proximity = " + event.values[0], Toast.LENGTH_SHORT).show(); } SensorEvent and the rate we want sensor events to be delivered

52. public class SensorExampleActivity extends Activity implements SensorEventListener {... protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL); } protected void onPause() { super.onPause(); mSensorManager.unregisterListener(this); } public void onSensorChanged(SensorEvent event) { Toast.makeText(this, "Proximity = " + event.values[0], Toast.LENGTH_SHORT).show(); } SensorEvent in onPause(), we want to stop listening for updates, preserving battery life

53. public class SensorExampleActivity extends Activity implements SensorEventListener {... protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL); } protected void onPause() { super.onPause(); mSensorManager.unregisterListener(this); } public void onSensorChanged(SensorEvent event) { Toast.makeText(this, "Proximity = " + event.values[0], Toast.LENGTH_SHORT).show(); } SensorEvent This is where we take action when there is a change in Sensor values

54. public class SensorExampleActivity extends Activity implements SensorEventListener {... protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL); } protected void onPause() { super.onPause(); mSensorManager.unregisterListener(this); } public void onSensorChanged(SensorEvent event) { Toast.makeText(this, "Proximity = " + event.values[0], Toast.LENGTH_SHORT).show(); } SensorEvent event.values[] array has important data about the sensor event

55. public class SensorExampleActivity extends Activity implements SensorEventListener {... protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL); } protected void onPause() { super.onPause(); mSensorManager.unregisterListener(this); } public void onSensorChanged(SensorEvent event) { Toast.makeText(this, "Proximity = " + event.values[0], Toast.LENGTH_SHORT).show(); } SensorEvent Refer to this page for details for each type of Sensorthis page

56. ProximitySensorExample.tar LightSensorExample.tar The code change between these two examples is very small SensorEvent

57. Using Sensors to Create a NUI NUI = Natural User Interface Human Computer Interaction is moving further and further away from the mouse and keyboard. o Being replaced by gestures on the device, air gestures, speech reco, and kinetics. There are typically two phases to gesture recognition o Data Gathering o Gesture Detection

58. Touch Using Gesture Detection you can register to listen for touch events on the device. o Long Press o Double Tap o Fling o Pinch o Multiple Finger gestures

59. Telepathy Can think of this gesture as an air gesture o Passing your hand over the device without touching the screen Might think that this would require a front facing camera to process this gesture.. o This would be an option but there is an easier way Use the Light Sensor to recognize the gesture o and the Proximity Sensor to validate

60. Microphone Using Speech is a no brainer for NUI o http://developer.android.com/reference/android/spee ch/RecognizerIntent.html http://developer.android.com/reference/android/spee ch/RecognizerIntent.html A more technical way of using the microphone requires signal processing o Way, way, way outside the scope of this class

61. Making Sense of the Data Thresholds o check peaks o filter peaks too close o based on count Time o combine with sensor data to get heart rate, for example Statistics are your friend o Since sensors spit out messy and noisy data o Mean, median, mode, range, etc

62. Starting Activities & Getting Results If you created two Activities A and B, you can start B from A, and have B return some result to A instead of o startActivity(Intent) call o startActivityForResult(Intent, int)

63. Starting Activities & Getting Results private int MY_CODE = 29; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void startSecondActivity(View v) { Intent intent = new Intent(A.this, B.class); startActivityForResult(intent, MY_CODE); }

64. Starting Activities & Getting Results private int MY_CODE = 29; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void startSecondActivity(View v) { Intent intent = new Intent(A.this, B.class); startActivityForResult(intent, MY_CODE); } This code is for Activity A

65. Starting Activities & Getting Results private int MY_CODE = 29; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void startSecondActivity(View v) { Intent intent = new Intent(A.this, B.class); startActivityForResult(intent, MY_CODE); } Some number that you want to use to identify your request. #29 is nothing special here.

66. Starting Activities & Getting Results private int MY_CODE = 29; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void startSecondActivity(View v) { Intent intent = new Intent(A.this, B.class); startActivityForResult(intent, MY_CODE); } I added a button to the XML and set the android:onClick attribute to this method

67. Starting Activities & Getting Results private int MY_CODE = 29; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void startSecondActivity(View v) { Intent intent = new Intent(A.this, B.class); startActivityForResult(intent, MY_CODE); } We have seen this before

68. Starting Activities & Getting Results private int MY_CODE = 29; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void startSecondActivity(View v) { Intent intent = new Intent(A.this, B.class); startActivityForResult(intent, MY_CODE); } Instead of startActivity(intent), we call startActivityForResult and give it the intent along with our "special" request code.

69. Starting Activities & Getting Results protected void onActivityResult(int requestCode, int resultCode, Intent data) { if(requestCode == MY_CODE) { if(resultCode == RESULT_OK) { // result is OK, add code here } We also need to add this method to Activity A, to react to when the result has been returned from Activity B.

70. Starting Activities & Getting Results public class B extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.second); } public void finishMe(View v) { setResult(Activity.RESULT_OK, null); finish(); }

71. Starting Activities & Getting Results public class B extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.second); } public void finishMe(View v) { setResult(Activity.RESULT_OK, null); finish(); } This code is for Activity B

72. Starting Activities & Getting Results public class B extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.second); } public void finishMe(View v) { setResult(Activity.RESULT_OK, null); finish(); } Assuming there's a Button with android:onClick="finishMe"

73. Starting Activities & Getting Results public class B extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.second); } public void finishMe(View v) { setResult(Activity.RESULT_OK, null); finish(); } Set the result of this Activity to OK. The second argument is an Intent, but we'll go in to this another time.

74. Starting Activities & Getting Results public class B extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.second); } public void finishMe(View v) { setResult(Activity.RESULT_OK, null); finish(); } Finish this Activity B, which will lead to onDestroy() being called, and Activity A becoming active. onActivityResult() in A will then be called.

75. Starting Activities & Getting Results See StartActivityForResultExample.tar

76. Starting Activities & Getting Results As another example, let's call upon an existing Android Activity for a result

77. Starting Activities & Getting Results static final int PICK_REQUEST = 1337; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void pickContact(View v) { Intent intent = new Intent(Intent.ACTION_PICK, Phone.CONTENT_URI); startActivityForResult(intent, PICK_REQUEST); } protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == PICK_REQUEST) { if (resultCode == RESULT_OK) { /* result is OK! */ } Here's our request code again

78. Starting Activities & Getting Results static final int PICK_REQUEST = 1337; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void pickContact(View v) { Intent intent = new Intent(Intent.ACTION_PICK, Phone.CONTENT_URI); startActivityForResult(intent, PICK_REQUEST); } protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == PICK_REQUEST) { if (resultCode == RESULT_OK) { /* result is OK! */ } Tied to a Button with android:onClick="pickContact"

79. Starting Activities & Getting Results static final int PICK_REQUEST = 1337; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void pickContact(View v) { Intent intent = new Intent(Intent.ACTION_PICK, Phone.CONTENT_URI); startActivityForResult(intent, PICK_REQUEST); } protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == PICK_REQUEST) { if (resultCode == RESULT_OK) { /* result is OK! */ } We use a different constructor for the Intent this time

80. Starting Activities & Getting Results static final int PICK_REQUEST = 1337; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void pickContact(View v) { Intent intent = new Intent(Intent.ACTION_PICK, Phone.CONTENT_URI); startActivityForResult(intent, PICK_REQUEST); } protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == PICK_REQUEST) { if (resultCode == RESULT_OK) { /* result is OK! */ } These two arguments must mean something together, they don't always do!

81. Starting Activities & Getting Results static final int PICK_REQUEST = 1337; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void pickContact(View v) { Intent intent = new Intent(Intent.ACTION_PICK, Phone.CONTENT_URI); startActivityForResult(intent, PICK_REQUEST); } protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == PICK_REQUEST) { if (resultCode == RESULT_OK) { /* result is OK! */ } There should be an Activity that recognizes this Intent

82. Starting Activities & Getting Results static final int PICK_REQUEST = 1337; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void pickContact(View v) { Intent intent = new Intent(Intent.ACTION_PICK, Phone.CONTENT_URI); startActivityForResult(intent, PICK_REQUEST); } protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == PICK_REQUEST) { if (resultCode == RESULT_OK) { /* result is OK! */ } If none exists, you will probably get Force Close

83. Starting Activities & Getting Results static final int PICK_REQUEST = 1337; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void pickContact(View v) { Intent intent = new Intent(Intent.ACTION_PICK, Phone.CONTENT_URI); startActivityForResult(intent, PICK_REQUEST); } protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == PICK_REQUEST) { if (resultCode == RESULT_OK) { /* result is OK! */ } Nothing new here

84. Starting Activities & Getting Results static final int PICK_REQUEST = 1337; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void pickContact(View v) { Intent intent = new Intent(Intent.ACTION_PICK, Phone.CONTENT_URI); startActivityForResult(intent, PICK_REQUEST); } protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == PICK_REQUEST) { if (resultCode == RESULT_OK) { /* result is OK! */ } That starts Activity B. When Activity B has returned, the result will be returned to this callback function

85. Understanding Implicit Intents Implicit Intents —specify the action that should be performed and optionally the URI which should be used in conjunction with the action Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(“http://www.google.com”)); o The Android system searches for all the components that are registered to handle this specific action o If the system only finds one component, then it will launch that automatically o If the system finds more than one component, it will pop up a dialog that will give the user the option of selecting the one they prefer o If none is found, you may get an Exception.

86. Understanding Implicit Intents Implicit Intents How do you know which Intent Action to specify for a given Uri?

87. Understanding Implicit Intents There are three rules, all of which must be true for a given activity to be eligible for a given intent 1.The activity must support the specified action 2.The activity must support the stated MIME type (if supplied) 3.The activity must support all of the categories named in the intent The upshot is that you want to make your intents specific enough to find the right receiver(s), and no more specific than that.

88. Understanding Implicit Intents Let's take a look at what happens when when the Home key is pressed...

89. Understanding Implicit Intents Open LogCat Click the + button to add a new filter Enter the following o Filter Name: ActivityManager o Log Tag: ActivityManager Now press the Home key on your device o For the Tag Column, look for ActivityManager o For the Text Column, look for anything beginning with "Starting: Intent..."  The last one should be the Intent that was used to launch the home screen o Mouseover that row, and you should see values for the following  act, which is the action - android.intent.action.MAIN  cat, which is the category - android.intent.category.HOME  in this case, there is no data, but sometimes there is o Note the action and category

90. Understanding Implicit Intents Can we create our own Home Screen app? Create a new project Open AndroidManifest.xml o add a new intent-filter to your Activity o the action should match the one you found in LogCat o so should the category o in addition, add the DEFAULT category

91. Understanding Implicit Intents Now press the Home key... For a nicer effect, make your Activity full-screen by adding this to the tag in the manifest file android:theme="@android:style/Theme.NoTitleBar.Fullscreen"

92. Understanding Implicit Intents See HomeScreenExample.tar

93. Understanding Implicit Intents It's not too difficult to figure out the Java code for the same Intent: or IntentFilter myFilter = new IntentFilter(Intent.ACTION_MAIN); myFilter.addCategory(Intent.CATEGORY_HOME);

94. Understanding Implicit Intents If you make your Intent Filters too vague too specific it won't match what you expect it to. Try to make your Intent Filters precise!

95. References The Busy Coder's Guide to Android Development - Mark Murphy The Busy Coder's Guide to Android Development - Mark Murphy Android Developers The Mobile Lab at Florida State University