Android Intents Nasrullah

Using the application context You use the application context to access settings and resources shared across multiple activity instances. You can retrieve the application context for the current process by using the getApplicationContext() method, like this: Context context = getApplicationContext(); Retreiving the applicatio resources String greeting = getResources().getString(R.string.hello);

Launching the activity There are a number of ways to launch an activity, including the following: 1.. Designating a launch activity in the manifest file 2.. Launching an activity using the application context 3.. Launching a child activity from a parent activity for a result

Launch activity in the manifestfile Each Android application must designate a default activity within the Androidmanifest file.

Launching Activity using Application Context The most common way to launch an activity is to use the startActivity() method of the application context. This method takes one parameter, called an Intent The following code calls the startActivity() method with an explicit intent: startActivity(new Intent(getApplicationContext(), MenuActivity.class));

This intent requests the launch of the target activity, named MenuActivity, by its class. This class must be implemented elsewhere within the package. Because the MenuActivity class is defined within this application’s package, it must be registered as an activity within the Android manifest file.

Intent to launch the web browser with specific url Uri address = Uri.parse(“ Intent surf = new Intent(Intent.ACTION_VIEW, address); startActivity(surf);

This example shows an intent that has been created with an action and some data.The action, in this case, is to view something. The data is a uniform resource identifier (URI), which identifies the location of the resource to view.For this example, the browser’s activity then starts and comes into foreground, causing the original calling activity to pause in the background. When the user finishes with the browser and clicks the Back button, the original activity resumes. Applications may also create their own intent types and allow other applications to call them, which makes it possible to develop tightly integrated application suites.

Launch an activity for a result Sometimes you want to launch an activity, have it determine something such as a user’s choice, and then return that information to the calling activity. When an activity needs a result, it can be launched using the Activity.startActivityForResult() method. The result is returned in the Intent parameter of the calling activity’s onActivityResult() method. We talk more about how to pass data using an Intent parameter in a moment.

Intents Intents are asynchronous messages which allow android components to request functionality from other components of the android components. An activity send an intent to another system which starts an other activity Intents are the instances of Android.content.Instance

Explicity Intent Explictiy intents explicitly name the component which should be called by the android system,by using the java class as identifier. Intent i = new Intent(this, ActivityTwo.class); i.putExtra("Value1", "This value one for ActivityTwo "); i.putExtra("Value2", "This value two ActivityTwo"); If this intent is correctly send to the android system,it will start the associated class.

Implicti Intents Implicit Intents do not specify the Java class which should be called. They specify the action which should be performed and optionally an URI which should be used for this action.

Gridlayout Android 4.0 (Ice Cream Sandwich) introduced a new type of layouts: the Gridlayout. Gridlayout is like the tag in HTML. child widgets are arranged in Cells made of Rows and Columns. Grid layout is a ViewGroup that can be used in constructing dashboard activities like that one in the Google Plus application:

Final in java In Java, final keyword is applied in various context. The final keyword is a modifier means the final class can't be extended, a variable can't be modified, and also a method can't be override