Intents are Awesome

Android Lover since 2008cofounder bubiloopcofounder android.es

Barcelona GTUG LeaderAndroid Dev at Fever

Head Mobile Dept. at ASMWS Computer Science at LaSalle

Israel Ferrer

INTENTS ARE AWESOME

really, trust me!

Israel Ferrer14th March

WHAT ARE INTENTS

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flickr : chinesetealover

intent |inˈtent| noun intention or purpose: with alarm she realized his intent | a real intent to cut back on social programs.

OK... WHAT DOES THIS REALLY MEAN?

Open new ScreensShare with other apps

Open Camera to take a photoOpen file managerOpen the browser

Open QR Code Scanner...

HOW INTENTS WORK

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Explicit Intent

Implicit Intent

theatricalintelligence

EXPLICIT INTENTS

• Explicit Intent names the component which should be called by the Android system, using the Java class as identifier.

• Used to open new activities in the same app.

final Intent intent=new Intent(this, LoginActivity.class);startActivity(intent);

IMPLICIT INTENTS• Implicit intent specifies the action to perform and optionally an

URI for the action.

• Implicit Intent is managed by Android Intent resolution, which maps the intent to a Service, Activity or Broadcasts Receiver

• This resolution is done by matching intent with intentFilters of every app.

• If more than one app can handle the action, the user will have to choose.

final Intent intent=new Intent(Intent.ACTION_VIEW, "http://mylookout.com");

SHARE DATA

• Intents can contain aditional data by using putExtra() method

• intent.putExtra(EXTRA_CONVERSATION, conversation);

• the receiving component can obtain this data by getExtras() methodBundle extras = getIntent().getExtras();String conversation = extras.getString(EXTRA_CONVERSATION);if (conversation != null) { // Do something with the data}

INTENT FILTERS

• An IntentFilter specifies the types of Intent that an activity, service, or broadcast receiver can respond to. IntentFilters are declared in the Android Manifest.

• There are 3 pieces of information used for this resolution:

• Action

• Type: mymeType or scheme.

• Category: need to support DEFAULT to be found by startActivity.

INTENT FILTERS

<activity android:name=".BrowserActivitiy" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.VIEW" /> <category android:name="android.intent.category.DEFAULT" /> <data android:scheme="http"/> </intent-filter></activity>

final Intent intent=new Intent(Intent.ACTION_VIEW, "http://mylookout.com");

Intent

IntentFilter

• Explicit: choose the component to call.

• Implicit: is a general intent with action and optionally URI. The Intent resolution call the component that can handle it.

• Intents can share data between components and apps.

TO SUM UP

HOW TO

USE INTENTS

?

• Reuse code and functionality from 3rd party apps

• ACTION_SEND

• ACTION_VIEW

• geo:lat,lon to open map

• http://host to open browser

• tel:number to open dialer

•Define a set of intents to handle web addresses.

• Example: Twitter

•Define IntentFilter to handle twitter urls

<activity android:name=".UrlHandleActivity" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.VIEW" /> <category android:name="android.intent.category.DEFAULT" /> <data android:host="www.twitter.com" android:scheme="http" /> </intent-filter></activity>

public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Uri uri = getIntent().getData(); if (null == uri) { // Shouldn't happen. Handle errors. finish(); return; }

String path = uri.getPath(); for (Pair<String, Class> pair : DISPATCH_MAP) { if (path.matches(pair.mFirst)) { Intent intent = new Intent(this, pair.mSecond); intent.setData(uri); startActivity(intent); finish(); return; } } finish(); } private static final List<Pair<String, Class>> DISPATCH_MAP = new LinkedList<Pair<String, Class>>();static { DISPATCH_MAP.add(new Pair<String, Class>("(.*)/status$", TweetActivity.class)); DISPATCH_MAP.add(new Pair<String, Class>("/another/path", ProfileActivity.class));}

• Check the URL path to fire target Activity

• Expose intents to 3rd party apps. Example: Lookout public backup intent.

CONCLUSIONS

A core component of Android.A way to reuse functionality between apps.

The glue between activities.The mashup concept into a mobile platformIntents are Awesome for users & developers

QUESTIONS?