ANDROID

Android Mobile
Application
Development
Assistant Lecturer
Mustafa Ghanem Saeed
Cihan University - Sulaimaniyah
Lecture Four
Computer science Department
Intents and Filters
Collage Of Science

What are intents?
• Intents are asynchronous messages which allow
application components to request functionality from
other Android components. Intents allow you to
interact with components from the same applications
as well as with components contributed by other
applications.
o For example, an activity can start an external activity for taking a picture.
• Intents are objects of the android.content.Intent type.
• Your code can send them to the Android system defining
the components you are targeting.
o For example, via the startActivity() method you can define that the intent should
be used to start an activity.
2
http://www.vogella.com/tutorials/AndroidIntent/article.html

Android intents are mainly used to:
(Question)
1. Open another Activity or Service from the
current Activity
2. Pass data between Activities and Services
3. Give responsibility to another application. For
example, you can use Intents to open the
browser application to display a URL.
4. Broadcast a message.
5. Dial a phone call etc.
3
http://www.javatpoint.com/android-intent-tutorial

Types of Android Intents
(Question)
1. Implicit Intent
o Implicit Intent specify the action which should be
performed and optionally data which provides
content for the action.
o For example, the following tells the Android system to
view a webpage. All installed web browsers should be
registered to the corresponding intent data via an
intent filter.
4

(Question) cont.
2- Explicit intents explicitly define the component which
should be called by the Android system, by using the Java
class as identifier.
o The following code demonstrates how you can start
another activity via an intent.
5
http://www.vogella.com/tutorials/AndroidIntent/article.html

(Question) cont.
1. use explicit intents to:
1. start a new activity
2. start an activity to get a result
3. start a service
4. broadcast an intent
5. start a new activity from within a broadcast receiver
2. use implicit intents to:
1. use other app’s components to:
1. send an email
2. pick a contact from the contacts list
3. make a phone call
3. use a pending intent to send a notification
6
https://www.101apps.co.za/articles/android-s-intents-and-intent-filters-a-tutorial.html

Intent Filters
 There are following Five elements in an intent filter:
1. Action
o It represent an activities action, what an activity is going to do.
2. Data
o There are two forms in which you can pass the data, using URI(Uniform
Resource Identifiers) or MIME type of data
3. Category
o This attribute of Intent filter dictates the behavior or nature of an Intent
4. Extras
o Key-value pairs for additional information that should be delivered to
the component handling the intent
5. Flags
o These flags are optional part of Intent object and instruct the Android
system how to launch an activity, and how to treat it after it's launched
etc.
7
http://abhiandroid.com/programming/intent-filter
Important Note: Every intent filter must contain action element in it. Data
and category element is optional for it.

Intent Filters-Action 1
 The Intent class defines a number of action constants,
including these:
8
http://www.linuxtopia.org/online_books/android/devguide/guide/topics/intents/intents-filters.html
Constant Target
component
Action
ACTION_CALL activity Initiate a phone call.
ACTION_EDIT activity Display data for the user to edit.
ACTION_MAIN activity Start up as the initial activity of a task, with no
data input and no returned output.
ACTION_SYNC activity Synchronize data on a server with data on the
mobile device.

Intent Filters-Action 2
 The Intent class defines a number of action constants,
including these:
9
Constant Target component Action
ACTION_BATTERY_LOW Broadcast Receiver A warning that the battery is
low.
ACTION_HEADSET_PLUG Broadcast Receiver A headset has been plugged
into the device, or unplugged
from it.
ACTION_SCREEN_ON Broadcast Receiver The screen has been turned
on.
ACTION_TIMEZONE_CHA
NGED
Broadcast Receiver The setting for the time zone
has changed.

Intent Filters- Data
 The URI of the data to be acted on and the MIME type of that data.
Different actions are paired with different kinds of data specifications.
• The URI: At the highest level a URI reference (Uniform
Resource Identifiers) in string form has the syntax
o [scheme:]scheme-specific-part[#fragment]
o For example:
• Short for Multipurpose Internet Mail Extensions, a
specification for formatting non-ASCII messages so that they
can be sent over the Internet. For Examples:
o For Text "text/plain"
o For Image :"image/jpeg“ , "image/bmp“ ,"image/gif“ , "image/jpg“ ,"image/png"
o For Video: "video/wav“, "video/mp4"
10
mailto:java-net@java.sun.com
news:comp.lang.java

Intent Filters- Data 2
Sr.No. Action/Data Pair & Description
1
ACTION_VIEW content://contacts/people/1
Display information about the person whose identifier is "1".
2
ACTION_DIAL content://contacts/people/1
Display the phone dialer with the person filled in.
3
ACTION_VIEW tel:123
Display the phone dialer with the given number filled in.
4
ACTION_DIAL tel:123
Display the phone dialer with the given number filled in.
5
ACTION_EDIT content://contacts/people/1
Edit information about the person whose identifier is "1".
11
<intent-filter . . . >
<data android:type="video/mpeg" android:scheme="http" . . . />
<data android:type="audio/mpeg" android:scheme="http" . . . />
. . .
</intent-filter>
Some examples of Action/Data Pair

Intent Filters- Category
 The Intent class defines several category constants,
including these (More than 29 category):
12
https://www.tutorialspoint.com/android/android_intent_standard_categories.htm
Constant Meaning
CATEGORY_BROWSABLE
The target activity can be safely invoked by the browser to
display data referenced by a link — for example, an image or an
e-mail message.
CATEGORY_DEFAULT
Set if the activity should be an option for the default action
(center press) to perform on a piece of data.
CATEGORY_APP_MAPS Used with ACTION_MAIN to launch the maps application.
CATEGORY_LAUNCHER
an activity on the top of stack, whenever application will start,
the activity containing this category will be opened first..

Intent Filters- Extras
13
https://www.tutorialspoint.com/android/android_intent_standard_extra_data.htm
• This will be in KEY-VALUE PAIRS for additional
information that should be delivered to the component
handling the intent. The extras can be set and read using
the putExtras() and getExtras() methods respectively
(More than 26 Extras):
• For examples :
• EXTRA_EMAIL: A String[] holding e-mail addresses that
should be delivered to.
• EXTRA_HTML_TEXT: A constant String that is
associated with the Intent, used with ACTION_SEND to
supply an alternative to EXTRA_TEXT as HTML formatted
text.
Intent i=new Intent(context,SendMessage.class);
i.putExtra("id", user.getUserAccountId()+"");
i.putExtra("name", user.getUserFullName());
context.startActivity(i);

Intent Filters- Flags 1
 Flags defined in the Intent class that function as
metadata for the intent. The flags may instruct the
Android system how to launch an activity and how to
treat it after it’s launched. (More than 33 Flags):
 FLAG_ACTIVITY_CLEAR_TASK - Clear any existing tasks on
this stack before starting the activity.
 FLAG_ACTIVITY_NEW_TASK - Start the activity in a new task
or reuse an existing task tied to that activity.
14
https://inthecheesefactory.com/blog/understand-android-activity-launchmode/en
Intent i=new Intent(this, Sample.class);
i.setFlags(Intent. FLAG_ACTIVITY_NEW_TASK);
startActivity(i);

Intent Filters- Flags 2
 How FLAG_ACTIVITY_NEW_TASK work:
 With normal intent StartActivity
 With FLAG_ACTIVITY_NEW_TASK:
15
https://inthecheesefactory.com/blog/understand-android-activity-launchmode/en

Important Questions?
 Define Android intents? Ans : Slide 2
 Mention mainly used of Android intents ? Ans : Slide 3
 Explain the Types of Android Intents? Ans : Slide 4,5
 Give Three examples of using Android Intents as : Ans : Slide 6
a) Use explicit intents?
b) Use implicit intent?
 What are the elements of intent filter list them with short definition ? Ans : Slide 7
 Give Three intent Action filter name and goal when apply on:
a) Activity? Ans : Slide 8
b) Broadcast Receiver? Ans : Slide 9
 Define Data intent filter and Explain (URL or MIME ) with example? Ans : Slide 7,10
 What is Category intent filter end explain only Two type of it? Ans : Slide 7,12
 Explain Extras intent filter and write sample java code to implement it ? Ans : Slide 7, 13
 Explain Flags intent filter and write sample java code to implement it ? Ans : Slide 7,14
16

Questions? Discussion?

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