In this file i describe all the important questions about android application development. What is Android? What is an Activity? Describe android application architecture? What is explicit intent? What is APK format? What is implicit intent? What language does Android support to develop an application?

1. Android Application Development (Assignment)
What is Android?
Androidisa mobile operatingsystemdevelopedby Google. It is based on a modified version of the
Linux kernel and other open source software, and is designed primarily for touchscreen mobile
devicessuchassmartphonesandtablets.Inaddition, Google has further developed Android TV for
televisions, Android Auto for cars and Wear OS for wrist watches, each with a specialized user
interface. Variants of Android are also used on game consoles, digital cameras, PCs and other
electronics.
What is an Activity?
An activityrepresentsasingle screenwithauserinterface justlikewindow orframe of Java.Android
activityisthe subclassof ContextThemeWrapperclass. Activity is a Java code that supports a screen
or UI. In otherwords,buildingblockof the user interface isthe activity.Activityclassisa pre-defined
class in Android and every application which has UI must inherit it to create window.
What are the notifications available in Android?
Toast Notification: Shows message that fades away after a few seconds. (Background type also)
Status Notification: Shows notification message and displayed till user action. (Background type
also)
Dialog Notification: Comes out of an active Activity.
Describe android application architecture?
Linux kernel:
At the bottomof the layersisLinux - Linux 3.6 withapproximately115patches. This provides a level
of abstraction between the device hardware and it contains all the essential hardware drivers like
camera,keypad,displayetc.Also,the kernel handlesall the thingsthatLinux isreallygoodatsuch as
networking and a vast array of device drivers, which take the pain out of interfacing to peripheral
hardware.
Libraries:
On topof Linux kernel there isasetof librariesincludingopen-source Web browser engine WebKit,
well known library libc, SQLite database which is a useful repository for storage and sharing of
applicationdata,libraries to play and record audio and video, SSL libraries responsible for Internet
security etc.
Application Framework:
The ApplicationFrameworklayerprovidesmanyhigher-level services to applications in the form of
Java classes.Applicationdevelopersare allowedtomake use of these services in their applications.

2. Applications:
You will find all the Android application at the top layer. You will write your application to be
installedonthislayeronly. Examples of such applications are Contacts Books, Browser, Games etc.
What is APK format?
Android Package (APK) is the package file format used by the Android operating system for
distribution and installation of mobile apps and middleware. APK files are analogous to other
software packages such as APPX in Microsoft Windows or a Debian package in Debian-based
operating system.
What is Intent?
Intentinthe Androidoperatingsystemisasoftware mechanismthat allows users to coordinate the
functions of different activities to achieve a task. Intent is a messaging object which provides a
facility for performing late runtime binding between the codes in different applications in the
Androiddevelopmentenvironment. It’smostsignificantuse isinthe launchingof activities,where it
can be thought of as the glue between activities: Intents provide an inter-application messaging
system that encourages collaboration and component reuse.
What is explicit intent?
In android,Explicit intentsexplicitlyspecifythe name of componenttobe invoked by an activity and
we use explicitintentstostarta componentinour ownapp.For example we can start a new activity
inresponse toa user actionusingexplicitintents.Byusingexplicitintentswe can send or share data
/ content from one activity to another activity based on our requirements. To create an Explicit
Intent, we need to define the component name for Intent object.

3. What is implicit intent?
Intent is something which is sent from one activity to inbuilt android activity in android. When we
workwithimplicitintents,we generallyspecifythe actionwhichwe want to perform and optionally
some data requiredforthataction.Data is typicallyexpressedasaUri whichcan representanimage
in the gallery or person in the contacts database.
The amount of applicationthatcan be done using implicit intents are many. Some of the examples
are as follows:
1. Call
2. Dialpad
3. Contact
4. Browser
5. Call Log
6. Gallery
7. Camera
What is an Android manifest file?
Every application must have an AndroidManifest.xml file (with precisely that name) in its root
directory.The manifestpresentsessential informationaboutthe application to the Android system,
information the system must have before it can run any of the application's code.
What language does Android support to develop an application?
The official language forAndroiddevelopmentisJava.Large parts of Androidare written in Java and
its APIs are designed to be called primarily from Java. It is possible to develop C and C++ app using
the Android Native Development Kit (NDK), however it isn't something that Google promotes.
What do ADT stands for?
ADT stands for Android Development Tools the Android SDK includes several tools and utilities to
help you create, test, and debug your projects.
What are the tools are placed in android SDK?
1. Android Studio
2. ADB (Android Debug Bridge)
3. AVD Manager
4. Eclipse
5. Fabric
6. FlowUp
7. GameMaker: Studio
8. Genymotion
9. Gradle
10. IntelliJ IDEA

4. What is viewgroup in android?
A ViewGroupisa special view that can contain other views (called children.) The view group is the
base class for layouts and views containers. This class also defines the ViewGroup.LayoutParams
class which serves as the base class for layouts parameters.
What is service in android?
A service is a component that runs in the background to perform long-running operations without
needing to interact with the user and it works even if application is destroyed.
What is content provider in Android?
A content provider manages access to a central repository of data. A provider is part of an Android
application,whichoftenprovidesitsownUI for working with the data. However, content providers
are primarilyintendedtobe usedby other applications, which access the provider using a provider
client object.