AndroidIntent

Erick Pranata

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Intent» An object that provides runtime binding

between separate components (such as two activities)

» The Intent represents an app’s "intent to do something.“˃ You can use intents for a wide variety of

tasks, but most often they’re used to start another activity.

» Types of Intent˃ Explicit˃ Implicit

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Explicit Intent© Sekolah Tinggi Teknik Surabaya

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Instantiate IntentIntent intent = new Intent( theContext, theActivityClass);» theContext: Who owns the Intent» TheActivityClass: to which the

system should deliver the Intent (in this case, the activity that should be started)

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Bundle» Intent may contain data to be passed to

other Activity.

intent.putExtra( "KEY_STRING", message);

» Best practice: use static constant to define "KEY_STRING" 5

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Bundle» Send more data as an object using

bundle

Bundle myBundle = new Bundle();myBundle.putInt("val1", 123);intent.putExtras(myBundle);

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Starting ActivitystartActivity(intent);

» Based on Intent object that was already instantiated

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Receive the Intent» Every Activity is invoked by an Intent,

regardless of how the user navigated there.» You can get the Intent that started your

activity by calling getIntent() and retrieve the data contained within it.

Intent intent = getIntent();String message = intent.getStringExtra( MainActivity.CONSTANT_NAME );

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Receive the Intent - Bundle

Bundle myBundle = intent.getExtras();

int x = myBundle.getint("val1");

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Implicit Intent© Sekolah Tinggi Teknik Surabaya

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Implicit Intent» It does not specify the app component to

start, but instead specifies an action and provides some data with which to perform the action.

» The system resolves the intent to an app that can handle the intent and starts its corresponding Activity.

» If there's more than one app that can handle the intent, the system presents the user with a dialog to pick which app to use.

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Caution!» If there are no apps on the device that

can receive the implicit intent, your app will crash when it calls startActivity().˃ Use resolveActivity()

+ If the result is non-null, there is at least one app that can handle the intent

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Common Intents» Alarm Clock» Calendar» Camera» Contacts/People App» Email» File Storage» Maps» Music or Video» Phone» Settings» Text Messaging» Web Browser

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Instantiate Common Intents

Intent common = new Intent(action, data);

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Some Common IntentsAction Data

ACTION_VIEW Uri.parse("http://www.google.com")

ACTION_WEB_SEARCH Uri.parse("http://www.google.com")

ACTION_DIAL Uri.parse("tel:555-555-5555")

ACTION_CALL Uri.parse("tel:555-555-5555")

ACTION_VIEW Uri.parse("geo:0,0?z=4&q=business+near+city“)

ACTION_SENDTO Uri.parse("sms:5551234")

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Some actions require permissions. Refer to http://developer.android.com/reference/android/Manifest.permission.html

Starting Activity and Getting Result© Sekolah Tinggi Teknik Surabaya

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From Recipient» Before an activity exits, it can call setResult(resultCode) to return a termination signal back to its parent.

» Always supply a result code, which can be the standard results Activity.RESULT_CANCELED, Activity.RESULT_OK, or any custom values.

» If a child activity fails for any reason (such as crashing), the parent activity will receive a result with the code RESULT_CANCELED. 18

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References» Starting Another Activity, https://

developer.android.com/training/basics/firstapp/starting-activity.html

» Common Intents, http://developer.android.com/guide/components/intents-common.html

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