Advance Android application development workshop day 4
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Transcript of Advance Android application development workshop day 4
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Intent
Allow you to interact with
components from the own and other
applications
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Types of Intent
• Explicit
• Implicit Intent
• An application can define the target component directly in the intent Explicit
• Ask the Android system to evaluate registered components based on the intent data implicit intents
Implicit
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Explicit Intent
Explicit Intent
The component which should be called by the Android system, by using the Java class as identifier , The following shows how to create an explicit intents and send it to the Android system
Typically used within an application as the classes in an application are controlled by the application developer
i.e :- Intent i = new Intent (This, SecondActivity.class);
startActivity(i);
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Implicit Intent
Implicit intents specify the action which should
be performed and optionally data which provides data for the action , For example
the following tells the Android system to view a webpage. All installed
web browsers should be registered to the corresponding intent
data
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Data transfer between activities using INTENT
An intent contains the action and optionally additional data
The component which creates the Intent can add data to it via the overloaded putExtra() method
Extras are key/value pairs; the key is always a String
This Intent object can be retrieved via the getIntent() method
The component which receives the intent can use the getIntent().getExtras() method call to get the extra data
i.e :- Bundle extras = getIntent().getExtras();
if (extras == null) {return;}// Get
data via the keyString value1 = extras.getString(Intent.EXTRA_TEXT);if (value1 != null) { // do something with the data}
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Android MANIFEST
Every application must have an AndroidManifest.xml file (with precisely that name) in its root directory
Manifest file for an android application is a resource file which contains all the details needed by the android system about the application
It is a key file that works as a bridge between the android developer and the android platform
It helps the developer to pass on functionality and requirements of our application to Android
This is an xml file which must be named as AndroidManifest.xml and placed at application root.
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Elements for application components
The set of attributes based on user interface
Specifies target activities
The operation provided by any library or API, running in background that is not visible
That makes to receive message broadcasted by the same application or by outside entity
Provides some structure to access application data
It specifies set of library files need to run the application
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Structure of Android Manifest.xml
<manifest><Elements for Application properties should come here -refer above for list><application><Elements for application components should come here -
refer above for list></application></manifest>
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Sample AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android"android:versionCode="1"android:versionName="1.0" > <uses-sdk android:minSdkVersion="7" /> <application
android:icon="@drawable/ic_launcher"android:label="@string/app_name" ><activity
android:label="@string/app_name"android:name=".HelloWorld" ><intent-filter >
<action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" />
</intent-filter></activity></application> </manifest>