Introduction to Android Development 

Eugeniu Arbuleac @arbuleac [email protected] Andrei Catinean @electryc [email protected] WHO WE ARE 

Activities and UI Intents Services Broadcast Receivers 

Activities and UI 

Activities and UI A screen Application = Σ activity 

Activity Lifecycle 

Managed by ActivityManager Activity Lifecycle 

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

D/MyActivity( 1146): onCreate D/MyActivity( 1146): onStart D/MyActivity( 1146): onResume First time run D/MyActivity( 1146): onClickAnotherActivity D/MyActivity( 1146): onPause D/MyActivity( 1146): onStop D/MyActivity( 1146): onRestart D/MyActivity( 1146): onStart D/MyActivity( 1146): onResume Open another activity, then Back button Activity Lifecycle 

D/MyActivity( 1146): onPause D/MyActivity( 1146): onStop D/MyActivity( 1146): onDestroy D/MyActivity( 1146): onCreate D/MyActivity( 1146): onStart D/MyActivity( 1146): onResume Rotate screen Activity Lifecycle 

D/MyActivity( 1146): onPause D/MyActivity( 1146): onStop Home Button D/MyActivity( 1146): onPause D/MyActivity( 1146): onStop D/MyActivity( 1146): onDestroy D/MyActivity( 1146): onCreate D/MyActivity( 1146): onStart D/MyActivity( 1146): onResume Rotate screen 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"); } Activity Lifecycle 

@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"); } } 

Declaring the Activity ... ... Let your application know about your Activity into the AndroidManifest.xml 

For your main activity use Intent Filters ... ... ... Let your application know about your Activity into the AndroidManifest.xml Declaring the Activity 

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

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

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

Layouts and views hierarchy 

Intents 

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

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

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

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

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

Intent Filters Activity Service Receiver Action 

Intent Filters Action Activity Service Receiver AndroidManifeset.xml 

Services 

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

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

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. Service Lifecycle 

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"); } } Service Example 

Called via its class name Declaring the Service Called via action 

Broadcast Receivers 

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

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

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() ); } } Broadcast Receiver Example 

Declaring it in AndroidManifest.xml Registering the Broadcast Receiver 

@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); } Registering the Broadcast Receiver Registering Programmatically 

Questions That’s all! 

Eugeniu Arbuleac @arbuleac [email protected] Andrei Catinean @electryc [email protected] THANK YOU