GDG Bucharest first meetup 2013

2. WHO WE ARE
Eugeniu Arbuleac Andrei Catinean
@arbuleac @electryc
arbuleac.ev@gmail.com andrei.catinean@gmail.com

3. Activities and UI

4. Activities and UI
Intents

5. Activities and UI
Intents
Services

6. Activities and UI
Intents
Broadcast Receivers
Services

7. Activities and UI

8. Activities and UI
A screen
Application = Σ activity

9. Activity Lifecycle

10. Activity Lifecycle
Managed by ActivityManager

11. Activity Lifecycle
$
¢ Managed by ActivityManager
Developer says what happens at each state

12. Activity Lifecycle
First time run
D/MyActivity( 1146): onCreate
D/MyActivity( 1146):
onStartD/MyActivity( 1146):
onResume
Open another activity, then Back button
D/MyActivity( 1146):
onClickAnotherActivityD/MyActivity( 1146):
onPauseD/MyActivity( 1146):
onStopD/MyActivity( 1146):
onRestartD/MyActivity( 1146):
onStartD/MyActivity( 1146): onResume

13. Activity Lifecycle
Rotate screen
D/MyActivity( 1146):
onPauseD/MyActivity( 1146):
onStopD/MyActivity( 1146):
onDestroyD/MyActivity( 1146):
onCreateD/MyActivity( 1146):
onStartD/MyActivity( 1146): onResume

14. Activity Lifecycle
Rotate screen
D/MyActivity( 1146):
onPauseD/MyActivity( 1146):
onStopD/MyActivity( 1146):
onDestroyD/MyActivity( 1146):
onCreateD/MyActivity( 1146):
onStartD/MyActivity( 1146): onResume
Home Button
D/MyActivity( 1146):
onPauseD/MyActivity( 1146):
onStop

15. Activity Lifecycle
package ro.gdgcluj.demoapp;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
public class MyActivity extends Activity {
static final String TAG = MyActivity.class.getSimpleName();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
Log.d(TAG, "onCreate");
}
@Override
protected void onStart() {
super.onStart();
Log.d(TAG, "onStart");
}
@Override
protected void onResume() {
super.onResume();
Log.d(TAG, "onResume");
}

16. @Override
protected void onPause() {
super.onPause();
Log.d(TAG, "onPause");
}
@Override
protected void onRestart() {
super.onRestart();
Log.d(TAG, "onRestart");
}
@Override
protected void onStop() {
super.onStop();
Log.d(TAG, "onStop");
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy");
}
}

17. Declaring the Activity
Let your application know about your Activity into the AndroidManifest.xml
<manifest ... >
<application ... >
<activity android:name=".MyActivity" />
...
</application ... >
...
</manifest >

18. Declaring the Activity
Let your application know about your Activity into the AndroidManifest.xml
<manifest ... >
<application ... >
<activity android:name=".MyActivity" />
...
</application ... >
...
</manifest >
For your main activity use Intent Filters
<manifest ... >
<application ... >
<activity android:name=".MyActivity" >
<intent-filter>
<action android:name= "android.intent.action.MAIN" />
<category android:name= "android.intent.category.LAUNCHER" />
<intent-filter />
<activity />
</application ... >
...
</manifest >

19. Building Android UI
XML
Declare UI in XML
Inflate XML in Java files

20. Building Android UI
XML Programmatically
Declare UI in XML VS. Initialize new widgets
Inflate XML in Java files Customize properties for each

21. Building Android UI
XML Programmatically
Declare UI in XML VS. Initialize new widgets
Inflate XML in Java files Customize properties for each
Use them both

22. Layouts and views hierarchy

23. Intents

24. Intents
Used to start activities, start/stop services, or send broadcasts

25. Using Intents
startActivity(Intent activity);
startService(Intent service);
stopService(Intent service);
sendBroadcast(Intent intent);

26. Explicit Intents
startActivity(new Intent(this, TargetActivity.class));
startService(new Intent(this, TargetService.class));

27. Explicit Intents
startActivity(new Intent(this, TargetActivity.class));
startService(new Intent(this, TargetService.class));
Implicit Intents
startService(new Intent("example.intent.action.IntentService"));
sendBroadcast(new Intent("example.intent.action.Receiver"));

28. Explicit Intents
startActivity(new Intent(this, TargetActivity.class));
startService(new Intent(this, TargetService.class));
Implicit Intents
startService(new Intent("example.intent.action.IntentService"));
sendBroadcast(new Intent("example.intent.action.Receiver"));
AndroidManifest.xml
<service android:name=".IntentService">
<intent-filter>
<action android:name="example.intent.action.IntentService" />
</intent-filter>
</service>
<receiver android:name=".Receiver">
<intent-filter>
<action android:name="example.intent.action.Receiver" />
</intent-filter>
</receiver>

29. Intent Filters
Activity
Action Service
Receiver

30. Intent Filters
Activity
Action Service
Receiver
AndroidManifeset.xml
<intent-filter>
<action android:name="any.action.you.want" />
</intent-filter>

31. Services

32. Services
Run in background
Don’t have UI
Run on the UI thread

33. Services
Run in background UI Activity
Don’t have UI startService(); stopService();
Run on the UI thread Service

34. Service Lifecycle
Service starts and "runs" until it
gets a request to stop
To offload work from main thread, use intent
service.
Intent service uses worker thread,
stops when done with work.

35. Service Example
package ro.gdgcluj.demoapp;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;
public class MyService extends Service {
static final String TAG = MyService.class.getSimpleName();
@Override
public IBinder onBind(Intent arg0) {
return null;
}
@Override
public void onCreate() {
Log.d(TAG, "onCreate");
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand");
return START_STICKY;
}
@Override
public void onDestroy() {
Log.d(TAG, "onDestroy");
}
}

36. Declaring the Service
Called via its class name
<service android:name=".ServiceDemo"></service>
Called via action
<service android:name=".IntentService">
<intent-filter>
<action android:name="example.intent.action.IntentService" />
</intent-filter>
</service>

37. Broadcast Receivers

38. Broadcast Receivers
Intent based publish-subscribe mechanism
Listening system events: incoming calls, SMS messages a.o.

39. Broadcast Receivers
Intent based publish-subscribe mechanism
Listening system events: incoming calls, SMS messages a.o.
Register for certain intents
Get notified when intent happens

40. Broadcast Receiver Example
package ro.gdgcluj.demoapp;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
public class Receiver extends BroadcastReceiver {
static final String TAG = Receiver.class.getSimpleName();
@Override
public void onReceive(Context context, Intent intent) {
Log.d(TAG, "onReceive action: "+intent.getAction() );
}
}

41. Registering the Broadcast Receiver
Declaring it in AndroidManifest.xml
<receiver android:name=".ReceiverDemo">
<intent-filter>
<action android:name="example.intent.action.Receiver" />
</intent-filter>
</receiver>

42. Registering the Broadcast Receiver
Registering Programmatically
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
...
// Create the receiver
receiver = new Receiver();
filter = new IntentFilter( ANY_INTENT_ACTION );
}
protected void onResume() {
super.onResume();
super.registerReceiver(receiver, filter);
}
@Override
protected void onPause() {
super.onPause();
unregisterReceiver(receiver);
}

43. That’s all!
Questions

44. THANK YOU
Eugeniu Arbuleac Andrei Catinean
@arbuleac @electryc
arbuleac.ev@gmail.com andrei.catinean@gmail.com