Introduction toandroid

Introduction to Android
Development

WHO WE ARE

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

Activities and UI
Intents

Broadcast Receivers

Services

Activities and UI

A screen

Application = Σ activity

Activity Lifecycle

Managed by ActivityManager

Activity Lifecycle

$

¢ Managed by ActivityManager

Developer says what happens at each state

Activity Lifecycle
First time run
D/MyActivity( 1146): onCreate
D/MyActivity( 1146): onStart
D/MyActivity( 1146): onResume

Open another activity, then Back button
D/MyActivity( 1146): onClickAnotherActivity
D/MyActivity( 1146): onPause
D/MyActivity( 1146): onStop
D/MyActivity( 1146): onRestart

Activity Lifecycle
Rotate screen
D/MyActivity( 1146): onDestroy

Activity Lifecycle
Rotate screen
D/MyActivity( 1146): onDestroy

Home Button

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");
}

@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

<manifest ... >
<application ... >
<activity android:name=".MyActivity" />
...
</application ... >
...
</manifest >

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 >

Building Android UI

XML

Declare UI in XML

Inflate XML in Java files

Building Android UI

XML Programmatically

Declare UI in XML VS. Initialize new widgets

Inflate XML in Java files Customize properties for each

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

Intents

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

Using Intents
startActivity(Intent activity);

startService(Intent service);

stopService(Intent service);

sendBroadcast(Intent intent);

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

startService(new Intent(this, TargetService.class));

Explicit Intents


Implicit Intents
startService(new Intent("example.intent.action.IntentService"));

sendBroadcast(new Intent("example.intent.action.Receiver"));

Explicit Intents


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>

Intent Filters
Activity

Action Service

Receiver

Intent Filters
Activity

Action Service

Receiver

AndroidManifeset.xml
<intent-filter>
<action android:name="any.action.you.want" />
</intent-filter>

Services

Run in background

Don’t have UI

Run on the UI thread

Services

Run in background UI Activity

Don’t have UI startService(); stopService();

Run on the UI thread Service

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.

Service Example

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;

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");
}

}

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>

Broadcast Receivers
Intent based publish-subscribe mechanism

Listening system events: incoming calls, SMS messages a.o.

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

Broadcast Receiver Example


import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

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() );
}

}

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>

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);
}

THANK YOU

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

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