Q. What is Android?
A. Android as a software stack—-or In other words,It is a set of software subsystems needed to deliver a fully functional solution—- for mobile devices. This stack includes an operating system (a modified version of the Linux kernel), middleware (software that connects the low-level operating system to high-level apps) that’s partly based on Java, and key apps (written in Java) such as a web browser (known as Browser) and a contact manager(known as Contacts).

Q. What is the latest version of Android ?
A. The latest version of Android operating system is Android 5.0 Lollipop which is the largest and most demanding release for Android yet.

Q. In what way Android is useful?
A. Android is useful as because-
1.It is simple and powerful SDK.
2.Licensing, Distribution or Development fee is not required.
3.Easy to Import third party Java library.
4.Supporting platforms are – Linux, Mac Os, Windows.

Q. What are the features of Android?
A. Android offers the following features:
-Application framework enabling reuse and replacement of app component.
-Bluetooth, EDGE, 3G, and WiFi support (hardware dependent).
-Camera, GPS, compass, and accelerometer support(hardware dependent).
-Dalvik virtual machine optimized for mobile devices.
-GSM Telephony support (hardware dependent).
-Integrated browser based on the open source WebKit engine.
-Media support for common audio, video, and still image formats (MPEG4, H.264, MP3, AAC, AMR, JPG, PNG, GIF).
-Optimized graphics powered by a custom 2D graphics library;3D graphics based on the OpenGL ES 1.0, 1.1, or 2.0 specification (hardware acceleration optional).
-SQLite for structured data storage.

Q. List the screen sizes supported by Android?
A. The screen sizes supported by Android are given below:
1.Small.
2.Normal.
3.Large.
4.Extra large.

Q.Which kernel(operating system) is used in Android?
A.Linux.(Android is based on 3.6 Linux version)

Q. How to stimulate SD card with emulator?
A. To stimulate SD card with emulator by using SD card check option in   emulator settings in AVD manager.

Q. What is the root tag used for app widet provider info xml file?
A. <appwidget-provider>

Q. Write a note on “multitasking in Android”?
A. Android supports multitasking at app level that is the reason
on creation of app it contain multitasking capabilities.One way to achieve multitasking,press home button on current task which will move it to the background and then you can start a new task from launcher.Another way is FLAG_NEW_TASK in the intent,when you are starting a new activity.

Q. What is .apk extension ?
A. The extension for an Android package file, which typically contains all of the files related to a single Android application. The file itself is a compressed collection of an AndroidManifest.xml file, application code (.dex files), resource files, and other files. A project is compiled into a single .apk file.

Q. How an Android components can communicate with each other?
A. Android components can communicate with each other by intent mechanism as they send Intents to activate each other and pass the data between them.

Q. What is the folder structure of an Android Application?
A. The folder structure of an Android Application-
1.src
2.gen
3.bin
4.res
5.values

Q. What are the key components of Android Architecture?
A. Android Architecture consists of four key components they are given below-
1.Linux Kernel
2.Libraries
3.Android Framework
4.Android Applications

Q. In what ways data stored in Android?
A. The ways that data stored in Android are-
1.SharedPreferences
2.Internal Storage
3.External Storage
4.SQLite Database
5.Network connection

Q. What are the types of Android applications?
A. The types of Android applications are given below-
1.Foreground
2.Background
3.Intermittent
4.Widget

Q. Write a note on “Activity”?
A. An activity is a component that presents a user interface screen with which the user interacts. For example, Android’s Contacts app includes an activity for entering a new contact, its Phone app includes an activity for dialing a phone number, and its Calculator app includes an activity for performing basic calculations.Although an app can include a single activity, it’s more typical for apps to include multiple activities. Activities are described by subclasses of the android.app.Activity class, which is an indirect subclass of the android.content.Context class.
Android calls during the life of an activity. For example, the SimpleActivity
class extends Activity and also overrides the void
onCreate(Bundle bundle) and void onDestroy() life cycle callback methods.

A Skeletal Activity

[code lang=”java”]import android.app.Activity;
import android.os.Bundle;
public class SimpleActivity extends Activity
{
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState); // Always call superclass method
first.
System.out.println("onCreate(Bundle) called");
}
@Override
public void onDestroy()
{
super.onDestroy(); // Always call superclass method first.
System.out.println("onDestroy() called");
}
} [/code]

The overriding onCreate(Bundle) and onDestroy() methods Here first
invoke their superclass counterparts, a pattern that must be followed when
overriding the void onStart(), void onRestart(), void onResume(), void
onPause(), and void onStop() life cycle callback methods.
-onCreate(Bundle) is called when the activity is first created.
-onStart() is called just before the activity becomes visible to the user.
-onRestart() is called after the activity has been stopped, just prior to it being started again.
-onResume() is called just before the activity starts interacting with the user.
-onPause() is called when Android is about to resume another activity.
-onStop() is called when the activity is no longer visible to the user.
-onDestroy() is called before the activity is destroyed, unless memory is tight and Android is forced to kill the activity’s process.

Q. What languages does Android support for application development?
A. Android applications are written using the Java programming language.

Q. When an app release resources?
A. Apps release resources in the onPause() method and restore them during onResume().

Q. Write a short note on Intents?
A. Intents are implemented as instances of the android.content.Intent class. An Intent object describes a message in terms of combination of the items like Action,Category,component name,Data,Extras,Flags,Type.
Intents can be classified as explicit or implicit.
An explicit intent designates the target component by its name.As component names are usually unknown. So explicit intents are typically used for app-internal messages.Android delivers an explicit intent to an instance of the designated target class. Only the Intent object’s component name matters.
An implicit intent doesn’t name a target.Implicit intents are often used to start components in other apps. Android searches for the best component to handle the implicit intent. During this, Android compares the contents of the Intent object to intent filters, manifestinformation associated with components that can potentially receive intents.
Filters advertise a component’s capabilities and identify only those intents that the component can handle. They open up the component to the possibility of receiving implicit intents of the advertised type. If a component has no intent filters, it can receive only explicit intents. But a component with filters can receive explicit and implicit intents.