Most Frequently question and answers in interview for Android Developer, Here is the some of question and answers collection:
5. 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.
6. What is .dex extension?
A.Android programs are compiled into .dex (Dalvik Executable) files, which are in turn zipped into a single
.apk file on the device. .dex files can be created by automatically translating compiled applications written in
the Java programming language.
7. Explain the Architecture of Android ?
A. Top -> Applications (Contacts, Browser, Phone, etc)
Below Applications -> Application Framework(Activity Manager, Window Manager, Content Providers, View
System, Package manager,
Telephony manager, Resource, Notification, Location managers)
Below Application Framework -> System Libraries(Like Sqlite, webkit, SSL, OpenGL, Media Framework etc)
& Android Runtime( Core Libraries and DVM).
Atlast Last -> Linux Kernel (which composed of drivers like display, camera etc.)
10. What is an activity?
A. A single screen in an application, with supporting Java code.
An activity presents a visual user interface for one focused endeavor the user can undertake.
For example, an activity might present a list of menu items users can choose from or it might display
photographs along with their captions.
11. What is a service?
A.A service doesn’t have a visual user interface, but rather runs in the background for an indefinite period of time.
For example, a service might play background music as the user attends to other matters, or it might fetch data over the network or calculate something and provide the result to activities that need it.Each service extends the Service base class.
12. How to Remove Desktop icons and Widgets?
A. Press and Hold the icon or widget. The phone will vibrate and on the bottom of the phone you will see anoption to remove. While still holding the icon or widget drag it to the remove button. Once remove turns red drop the item and it is gone
13. Describe a real time scenario where android can be used?
A .Imagine a situation that you are in a country where no one understands the language you speak and you can
not read or write. However, you have mobile phone with you.
14. Is there a unique Android device ID?
A: Settings.Secure#ANDROID_ID returns the Android ID as an unique 64-bit hex string.
import android.provider.Settings.Secure;
private String android_id = Secure.getString(getContext().getContentResolver(),
Secure.ANDROID_ID);
15. What languages does Android support for application development?
A.Android applications are written using the Java programming language.
16. Describe Android Application Architecture?
A.Android Application Architecture has the following components:
• Services – like N
• Intent – To perform inter-communication network Operation between activities or services
• Resource Externalization – such as strings and graphics
• Notification signaling users – light, sound, icon, notification, dialog etc
17. What is the Android Open Source Project?
A. We use the phrase “Android Open Source Project” or “AOSP” to refer to the people, the processes, and the source code that make up Android.
18. Why did we open the Android source code?
A .Google started the Android project in response to our own experiences launching mobile apps. We wanted to make sure that there would always be an open platform available for carriers, OEMs, and developers to use to make their innovative ideas a reality. We also wanted to make sure that there was no central point of failure, so that no single industry player could restrict or control the innovations of any other. The single most important goal of the Android Open-Source Project (AOSP) is to make sure that the open-source Android software is implemented as widely and compatibly as possible, to everyone’s benefit.
19. What is a ContentProvider and what is it typically used for?
A: ContentProvider manages access to a structured set of data. It encapsulates the data and provide mechanisms for defining data security. ContentProvider is the standard interface that connects data in one process with code running in another process.
20. When does onResume() method called?
A: onResume() method is an activity lifecycle method. This is called when the activity come to foreground. You can override this method in your activity to execute code when activity is started, restarted or comes to foreground.
21. Will it work on my phone?
A.The app will work on all phones and tablets running Android version 1.6 and above.
22. How much does it cost?
A.The app is free and ad-supported.
23. How do I save the app to my SD card?
A. From the device's Settings menu, go to Applications > Manage applications > The Guardian. Under the data
header, choose "Move to SD card".
24. What is the use of WebView in android?
A : WebView is an android UI component that displays webpages. It can either display a remote webpage or can also load static HTML data. This encompasses the functionality of a browser that can be integrated to application. WebView uses the WebKit rendering engine to display web pages and includes methods to navigate forward and backward through a history, zoom in and out, etc.
25. How to get screen dimensions in pixels in Andorid Devices?
A: int screenHeight = getResources().getDisplayMetrics().heightPixels;
int screenWidth = getResources().getDisplayMetrics().widthPixels;
26. What is Mono for Android?
A. Mono for Android is a software development kit that allows developers to use the C# language to create mobile applications for Android-based devices.Mono for Android exposes two sets of APIs, the core .NET APIs that C# developers are familiar with as well as a C# binding to Android's native APIs exposed through the Mono.Android.* namespace.You can use Mono for Android to develop applications that are distributed through the Android Application Stores or to deploy software to your personal hardware or the Android simulator.
27. Difference between Activity Context and Application Context?
A:They are both instances of Context, but the application instance is tied to the lifecycle of the application, while the Activity instance is tied to the lifecycle of an Activity. Thus, they have access to different information about the application environment.
If you read the docs at getApplicationContext it notes that you should only use this if you need a context whose lifecycle is separate from the current context.
28. What is the difference between a fragment and an activity? Explain the relationship between the two?
A:An activity is typically a single, focused operation that a user can perform (such as dial a number, take a picture, send an email, view a map, etc.). Yet at the same time, there is nothing that precludes a developer from creating an activity that is arbitrarily complex.
Activity implementations can optionally make use of the Fragment class for purposes such as producing more modular code, building more sophisticated user interfaces for larger screens, helping scale applications between small and large screens, and so on. Multiple fragments can be combined within a single activity and, conversely, the same fragment can often be reused across multiple activities. This structure is largely intended to foster code reuse and facilitate economies of scale.
A fragment is essentially a modular section of an activity, with its own lifecycle and input events, and which can be added or removed at will. It is important to remember, though, that a fragment’s lifecycle is directly affected by its host activity’s lifecycle; i.e., when the activity is paused, so are all fragments in it, and when the activity is destroyed, so are all of its fragments.
29. What is 'Context' on Android?
A: Context of current state of the application/object. It lets newly-created objects understand what has been going on. Typically you call it to get information regarding another part of your program (activity and package/application).
You can get the context by invoking getApplicationContext(), getContext(), getBaseContext() or this (when in the activity class).
30. Where is the UI Designer?
A. Mono for Android does not bundle a UI designer to create the UI XML files We do not provide an
integrated UI designer in Mono for Android 1.0. No decisions past that have been made. We will be listening to user feedback to decide where to put resources for the future versions.
31. What is the difference between Service and IntentService? How is each used?
A: Service is the base class for Android services that can be extended to create any service. A class that directly extends Service runs on the main thread so it will block the UI (if there is one) and should therefore either be used only for short tasks or should make use of other threads for longer tasks.
IntentService is a subclass of Service that handles asynchronous requests (expressed as “Intents”) on demand. Clients send requests through startService(Intent) calls. The service is started as needed, handles each Intent in turn using a worker thread, and stops itself when it runs out of work. Writing an IntentService can be quite simple; just extend the IntentService class and override the onHandleIntent(Intent intent) method where you can manage all incoming requests.
32. What is the API profile exposed by Mono for Android?
A. Mono for Android uses the same API profile for the core libraries as MonoTouch.Specifically, MonoTouch and Mono for Android both support a Silverlight-based API, without Silverlight's UI libraries (e.g. no XML, no WindowsBase.dll, etc.), and free of the sandboxing limitations of Silverlight.
33. Are the Android releases available in a ROM?
A. No, Android is not yet available in a ROM format.Currently Android is installed by using a clean SD Card, and booted from there.It is booted by running a special application called 'Haret.exe' residing on your SD Card which will terminate the Windows kernel and boot into Linux/Android.It can't easily be run from ROM because a) it's too experimental to risk putting in ROM and then killing a device and b) WinMo does some hardware initialization that isn't documented, but is needed before Android can run.
34. When will it be available in a ROM?
A. No time soon. Folks are working on it, but you'll need a lot of patience before it (if ever) arrives
35. How do I turn off, or reboot Android?
A. In earlier releases, you had to pull the battery or press the reset button, in newer releases, you can hold down the 'end call' button and see a menu.
36. What is DDMS? Describe some of its capabilities.
A: DDMS is the Dalvik Debug Monitor Server that ships with Android. It provides a wide array of debugging features including:
37. What if my app uses location API, and service provider shuts that off, can they?
A. They can do that... it’s not a perfect world. Rather than having us dictate what carriers and OEMs support,
we let developers develop killer apps that will require it.
We want to ensure all the application development that goes on for Android... we want to give OEMs an
incentive to keep things open. It’s a positive, self fulfilling vision.
38.If I’m a game developer and I’m building piece of content and I want to sell it, how do I do that and realize revenue?
A. Content distribution — we’ve thought of that. It’d be great if there were a place where people could go to
safely download and pay for content.
39. We use SMS interception for system signalling. Is there a mechanism for an app to respond and stop the signaling chain? Is there security around that so that one vendor can’t hijack a message and respond to it?
A. There’s a mechanism where an application can register to receive a message with a certain signature and
prevent others from getting it. We have a system of permissions apps are able to declare, enforce, and require to
perform certain operations. Things like dial the phone, get to contacts, etc.. But these aren’t things that are
baked in the core of the system. An arbitrary app could declare custom permissions.
As far as restricting another app, the model we’ve been going by... the phone is not controlled by the
application vendor, it’s controlled by the user. Whether or not the permissions are granted is up to the user that
owns the phone. If you created a protocol that intercepts an SMS and another party wrote an app that intercepts
the same SMS and the user wants to use that, the user could be free to stick that in.
40. Can the user set a priority?
A. Don’t know, post your question to the developer’s community board.
41. Which of the code snippets below is the correct way to check if a Compass sensor is present on the system? Explain your answer.
Answer 1:
PackageManager m = getPackageManager();
if (!m.hasSystemFeature(PackageManager.FEATURE_SENSOR_COMPASS)) {
// This device does not have a compass, turn off the compass feature
}
Answer 2:
SensorManager m = getSensorManager();
if (!m.hasSystemFeature(SensorManager.FEATURE_SENSOR_COMPASS)) {
// This device does not have a compass, turn off the compass feature
}
Answer 3:
Sensor s = getSensor();
if (!s.hasSystemFeature(Sensor.FEATURE_SENSOR_COMPASS)) {
// This device does not have a compass, turn off the compass feature
}
42. What’s so special about Android?
A. Unlike the proprietary iPhone operating system (now known as "iOS,"), which is under the complete control of Apple — and the same goes for Research in Motion’s BlackBerry OS or Microsoft’s Windows Phone platform — Google released Android as an open-source OS under the auspices of the Open Handset Alliance,leaving phone manufacturers (relatively) free to tweak Android as they see fit for a given handset.
That’s one thing that’s special about Android. Another thing is that it just happens to be a really good OS, the first one in the post-iPhone wireless era to really give Apple a run for its money. Android may not be as sleek or polished as iOS (that’s my humble opinion, at least), but it’s fast and powerful, with an intuitive user interface that’s packed with options and flexibility. It’s also being constantly improved courtesy of the big brains at Google, making the Android experience sleeker by the day.
43. What is a portable wi-fi hotspot?
A:The portable wi-fi hotspot is used to share internet connection to other wireless devices.
44. What is NDK?
A. NDK stands for Native Development Kit. By using NDK, you can develop a part of app using native language such as C/C++ to boost the performance.
45. What is needed to make a multiple choice list with a custom view for each row?
A. Multiple choice list can be viewed by making the CheckBox android:id value be “@android:id /text1″. That is the ID used by Android for the CheckedTextView in simple_list_item_multiple_choice.
46. What are the life cycle methods of android activity?
A:There are 7 life-cycle methods of activity. They are as follows:
onCreate()
onStart()
onResume()
onPause()
onStop()
onRestart()
onDestroy()
47. Difference between px, sp, dip, dpi and pt in Android?
A: px is one pixel. px is corresponds to actual pixels on the screen.
sp is scale-independent pixels. SP is like the dp unit, but it is also scaled by the user's font size preference.
dip is Density-independent pixels.
dpi is Dots per inches.
pt is points.
48. What are the approaches required to share persistent user-defined objects?
A: Persistent objects come when there is process that is in the running state and the system can perform any action like restart or kill. If there is any data that will persist and required from another data then it is very essential to save it and share it so that if one activity is down, another activity can be performed without any hindrance. To share the complex persistent user-defined objects, it is required to have the approaches like:
- Application preferences: that is used to allow the user to change the setting of preferences and make it accessible by some other objects.
- Files: permissions on the files can be set so that any other file can also use and share the objects
- Content providers: allow easy to follow patterns that allow the user to select the object and share it with other functions.
- Database: the database can be used to store the user data and can easily link between the user and the entity that are present in it.
51. How will you record a phone call in Android? How to get a handle on Audio Stream for a call in Android?
A. Permissions.PROCESS_OUTGOING_CALLS: Allows an application to monitor, modify, or abort outgoing
calls.
52. Why cannot you run standard Java bytecode on Android?
A. Android uses Dalvik Virtual Machine (DVM) which requires a special bytecode. We need to convert Java
class files into Dalvik Executable files using an Android tool called "dx". In normal circumstances, developers
will not be using this tool directly and build tools will care for the generation of DVM compatible files.
53. Can you deploy executable JARs on Android? Which packaging is supported by Android?
A. No. Android platform does not support JAR deployments. Applications are packed into Android Package
(.apk) using Android Asset Packaging Tool (aapt) and then deployed on to Android platform. Google provides
Android Development Tools for Eclipse that can be used to generate Android Package.
54. Does android support other language than java?
A:Yes, android app can be developed in C/C++ also using android NDK (Native Development Kit). It makes the performance faster. It should be used with android SDK.
55. What is an action?
A. The Intent Sender desires something or doing some task
56. What are Dalvik Executable files?
A. Dalvik Executable files have .dex extension and are zipped into a single .apk file on the device.
57. How does Android system track the applications?
A. Android system assigns each application a unique ID that is called Linux user ID. This ID is used to track
each application.
58. When does Android start and end an application process?
A. Android starts an application process when application's component needs to be executed. It then closes the
process when it's no longer needed (garbage collection).
59. How can two Android applications share same Linux user ID and share same VM?
A. The applications must sign with the same certificate in order to share same Linux user ID and share same
VM.
60. Write code snippet to retrieve IMEI number of Android phone.
A. TelephonyManager class can be used to get the IMEI number. It provides access to information about the telephony services on the device.
Code
TelephonyManager mTelephonyMgr = (TelephonyManager)
getSystemService(Context.TELEPHONY_SERVICE);
String imei = mTelephonyMgr.getDeviceId();
61. How can I download the GoToMeeting app?
A. You can download the GoToMeetng app from the Android Market by signing in to your Google account
linked with your Android device and searching for the GoToMeeting app to install it. If you don’t see an Install
button, you may not be running Android 2.2 or higher – the minimum system requirement needed to install the
GoToMeeting app.
You can also download the GoToMeeting app from the Amazon Appstore (only available in the U.S.), which
lets you instantly download the GoToMeeting app to an Android device.
If you have the GoToMeeting app pre-loaded onto your device, you’ll need to first upgrade to the latest version
of GoToMeeting. To upgrade, select the GoToMeeting daisy icon and then select the Upgrade button to install
the most recent version of the app.
62.If I have a Motorola Android-based device that doesn’t have the Android Market app, can I still
download the GoToMeeting app?
A.Yes. Attendees using Motorola Android-based devices in China can now download the GoToMeeting app
from SHOP4APPSTM – Motorola’s preinstalled Android application storefront. The GoToMeeting app is not yet
localized in Chinese, but it is available in English, German, French, Spanish and Italian.
63.Is there a way to run Python on Android?
A:One way is to use Kivy:
- Open source Python library for rapid development of applications that make use of innovative user interfaces, such as multi-touch apps.
- Kivy runs on Linux, Windows, OS X, Android and iOS. You can run the same [python] code on all supported platforms.
64. How you can use built-in Messaging within your application?
A: You can use an Intent object to activate the built-in Messaging service. You have to pass MIME type “vnd.android-dir/mms-sms”, in setType method of Intent as shown in the following given below code.
Intent intent = new Intent (android.content.Intent.ACTION_VIEW);
intent.putExtra("address", "5556; 5558;");// Send the message to multiple recipient.
itent.putExtra("sms_body", "Hello my friends!");
intent.setType("vnd.android-dir/mms-sms");
startActivity(intent);
65. Does Android support Adobe Flash in the browser?
A.Flash support varies by device with Android 2.1. The Samsung Acclaim does not have Flash support upon
launch, but the HTC Desire will support Flash Lite 4.0 running Android 2.1. Flash 10.1 support is coming to
Android-powered phones with Android 2.2.
66.Does Android support push email or is it pull?
A. Android 2.1 supports push e-mail for Exchange mail and Gmail.
67. Will these phones have world phone capabilities, with the ability to make calls, receive data in other countries? Or will they be able to use Google Voice to make calls?
A.Our Android-powered phones have Wi-Fi which can be used abroad for data, including Google Voice for
making international calls. International Roaming for voice is available in several countries.
68. Will the App run on my Android phone?
A. Yes, our App is fully compatible with any Android phone running Android software v2.1 or later.
69. How do I install your App?
A. You can install our App from the Android Market by following the below steps:
Open the Android Market application in the Applications menu.
Hit the search icon and type in E.ON
To install it, hit the ‘Free’ button on the left hand side
In the next screen, it will give you more details about the application including the different functionalities it
will need to access. Just click on OK to finish installing the application.
70. How do I find and download updates to the E.ON Android application?
A. Any updates to our App will appear on your notification menu at the top of your screen. Just tap on the E. App icon and you'll be taken into the Android Market and be presented with the E.ON App download page.
71. What is a service in android?
The Service is like as an activity to do background functionalities without UI interaction.
72. What is an Intent?
A class (Intent) which describes what a caller desires to do. The caller will send this intent to Android's intent
resolver, which finds the most suitable activity for the intent. E.g. opening a PDF document is an intent, and the
Adobe Reader apps will be the perfect activity for that intent (class).
73. What is a Sticky Intent?
A. Sticky Intent is also a type of Intent which allows a communication between a function and a service
sendStickyBroadcast() performs a sendBroadcast(Intent) known as sticky, i.e. the Intent you are sending stays
around after the broadcast is complete, so that others can quickly retrieve that data through the return value of
registerReceiver(BroadcastReceiver, IntentFilter). In all other ways, this behaves the same as
sendBroadcast(Intent). One example of a sticky broadcast sent via the operating system is
ACTION_BATTERY_CHANGED. When you call registerReceiver() for that action -- even with a null
BroadcastReceiver -- you get the Intent that was last broadcast for that action. Hence, you can use this to find
the state of the battery without necessarily registering for all future state changes in the battery.
74. How the nine-patch Image different from a regular bitmap? Alternatively, what is the difference between nine-patch Image vs regular Bitmap Image?
A.It is one of a resizable bitmap resource which is being used as backgrounds or other images on the device.
The NinePatch class allows drawing a bitmap in nine sections. The four corners are unscaled; the middle of the
image is scaled in both axes, the four edges are scaled into one axis.
75. What is a resource?
A. user defined JSON, XML, bitmap, or other file, injected into the application build process, which can later be
loaded from code.
76.How will you record a phone call in Android? or How to handle an Audio Stream for a call in Android?
Permission.PROCESS_OUTGOING_CALLS: Will Allow an application to monitor, modify, or abort outgoing
calls. So using that permission we can monitor the Phone calls.
77.Does Android support the Bluetooth serial port profile?
Yes.
78. Can an application be started on powerup?
Yes.
79. How to Translate in Android?
The Google translator translates the data of one language into another language by using XMPP to transmit
data. You can type the message in English and select the language which is understood by the citizens of the
country in order to reach the message to the citizens.
80. Describe Briefly the Android Application Architecture
Android Application Architecture has the following components:
Services like Network Operation
Intent - To perform inter-communication between activities or servicesResource Externalization - such as
strings and graphics
Notification signaling users - light, sound, icon, notification, dialog etc.
Content Providers - They share data between applications
81. What is needed to make a multiple choice list with a custom view for each row?
A. Multiple choice list can be viewed by making the CheckBox android:id value be “@android:id /text1". That
is the ID used by Android for the CheckedTextView in simple_list_item_multiple_choice.
82. What dialog boxes are supported in Android ?Android supports 4 dialog boxes:
AlertDialog: An alert dialog box supports 0 to 3 buttons and a list of selectable elements, including
check boxes and radio buttons. Among the other dialog boxes, the most suggested dialog box is the alert
dialog box.
ProgressDialog: This dialog box displays a progress wheel or a progress bar. It is an extension of
AlertDialog and supports adding buttons.
DatePickerDialog: This dialog box is used for selecting a date by the user.
TimePickerDialog: This dialog box is used for selecting time by the user.
83.What are the notifications available in android?
A:
Toast Notification − It will show a pop up message on the surface of the window
Status Bar Notification − It will show notifications on status bar
Dialogue Notification − It is an activity related notification.
84.Features of Android:
Application framework enabling reuse and replacement of components
Dalvik virtual machine optimized for mobile devices
Integrated browser based on the open source WebKit engine
Optimized graphics powered by a custom 2D graphics library; 3D graphics based on the OpenGL ES 1.0
specification (hardware acceleration optional)
SQLite for structured data storage
Media support for common audio, video, and still image formats (MPEG4, H.264, MP3, AAC, AMR, JPG,PNG, GIF)
GSM Telephony (hardware dependent)
Bluetooth, EDGE, 3G, and WiFi (hardware dependent)
Camera, GPS, compass, and accelerometer (hardware dependent)
Rich development environment including a device emulator, tools for debugging, memory and performance
profiling, and a plugin for the Eclipse IDE.
85.What is an Application ?A. Collection of one or more activities, services, listeners, and intent receivers. An application has a single
manifest, and is compiled into a single .apk file on the device.
86.What is a Content Provider ?
A. A class built on ContentProvider that handles content query strings of a specific format to return data in a
specific format. See Reading and writing data to a content provider for information on using content providers.
87. What is a Dalvik ?
A. The name of Android’s virtual machine. The Dalvik VM is an interpreter-only virtual machine that executes
files in the Dalvik Executable (.dex) format, a format that is optimized for efficient storage and memory-
mappable execution. The virtual machine is register-based, and it can run classes compiled by a Java language
compiler that have been transformed into its native format using the included “dx” tool. The VM runs on top of
Posix-compliant operating systems, which it relies on for underlying functionality (such as threading and low
level memory management). The Dalvik core class library is intended to provide a familiar development base
for those used to programming with Java Standard Edition, but it is geared specifically to the needs of a small
mobile device.
88.What is an DDMS ?
A. Dalvik Debug Monitor Service, a GUI debugging application shipped with the SDK. It provides screen
capture, log dump, and process examination capabilities.
89.What is Drawable?
A. A compiled visual resource that can be used as a background, title, or other part of the screen. It is compiled
into an android.graphics.drawable subclass.
90.What are fragments in Android Activity ?
A. Fragment represents a behavior or a portion of user interface in an Activity. And it is a self-contained
component with its own UI and lifecycle.
91. What is Service?
A. Service doesn't have a visual user interface , but rather runs in the background for an indefinite period of
time. For Example, a service might play background for music as the user attends to other matters.
92. What is BroadReceivers?
A. BroadcastReceiver is a component that does nothing but receive and react to broadcast announcements.
For example, the battery is low or that the user changed a language preference.
94.How many ways data stored in Android?
1.SharedPreferences
2.Internal Storage
3.External Storage
4.SQLite Database
5.Network connection
95. Types of Android applications?
1.Foreground
2.Background
3.Intermittent
4.Widget
96. Android Development Tools?
A. The Android SDK and Virtual Device Manager Used to create and manage Android Virtual Devices (AVD)
and SDK packages.
The Android Emulator An implementation of the Android virtual machine designed to run within a virtual
device on your development computer. Use the emulator to test and debug your Android applications.
Dalvik Debug Monitoring Service(DDMS) Use the DDMS perspective to monitor and control the Dalvik virtual
machines on which your debugging your application.
Android Asset Packaging Tool(AAPT) Constructs the destributable Android packages files (.apk).
Android Debug Bridge(ADB) A client-server application that provedes a link to a running emulator.It lets you
copy files, install compiled application packages(.apk),and run shell commands.
97.What is View in Android?
A. Views are the base class for all visual interface elements(commonly known as controls or widgets).
All UI controls,including the layout classes,are derived for View.
98. What View Group in Android?
A. View Groups are extensions of the View class that can contain multiple child View.Extend the ViewGroupclass to create compound controls made up of interconnected child Views.
A: They're the same thing (in API Level 8+). Use match_parent.
FILL_PARENT (renamed MATCH_PARENT in API Level 8 and higher), which means that the view wants to be as big as its parent (minus padding)
fill_parent: The view should be as big as its parent (minus padding). This constant is deprecated starting from API Level 8 and is replaced by match_parent
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It is also include above, some are missing please don't forget to solve this also:
Android
Interview Question/Answers and Tips
This answer provides a list of effective and
commonly used Android interview questions . I have posted both the
questions and answer .
1.What is the manifest file and how is it used?
Answer: Every Android app must have this
manifest file in its root directory named ‘AndroidManifest.xml’.
The file includes critical information about the app, including the
Java package name for the application.
Bonus follow up question: What is the first
element in the AndroidManifest file, right after the encoding
declaration?
A: ‘manifest’ Note: The
‘permissions’ element is the next best answer if the developer
assumed you meant the first element within the ‘manifest’
structure.
2. ways Android allows you to store data?
A: Any of the following 5 possible
options are acceptable:
1.SharedPreferences
2.Internal Storage
3.External Storage
4.SQLite Database
5.Network connection
3.What items or folders are important in every
Android project?
A: The developer should name at least
4 of these 6 items below, as these are essential within each Android
project:
1. AndroidManifest.xml
2. build.xml
3. bin/
4. src/
5. res/
6. assets/
4.What is ANR?
A: ANR stands for “Application Not
Responding”. It’s a dialog box that appears when an application
doesn’t respond for more than 10 seconds (sometimes it can be less
than 10 seconds). The ANR dialog box offers the user the option of
either closing the app or waiting for it to finish running.
5. 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.
6. What is .dex extension?
A.Android programs are compiled into .dex (Dalvik Executable) files, which are in turn zipped into a single
.apk file on the device. .dex files can be created by automatically translating compiled applications written in
the Java programming language.
7. Explain the Architecture of Android ?
A. Top -> Applications (Contacts, Browser, Phone, etc)
Below Applications -> Application Framework(Activity Manager, Window Manager, Content Providers, View
System, Package manager,
Telephony manager, Resource, Notification, Location managers)
Below Application Framework -> System Libraries(Like Sqlite, webkit, SSL, OpenGL, Media Framework etc)
& Android Runtime( Core Libraries and DVM).
Atlast Last -> Linux Kernel (which composed of drivers like display, camera etc.)
10. What is an activity?
A. A single screen in an application, with supporting Java code.
An activity presents a visual user interface for one focused endeavor the user can undertake.
For example, an activity might present a list of menu items users can choose from or it might display
photographs along with their captions.
11. What is a service?
A.A service doesn’t have a visual user interface, but rather runs in the background for an indefinite period of time.
For example, a service might play background music as the user attends to other matters, or it might fetch data over the network or calculate something and provide the result to activities that need it.Each service extends the Service base class.
12. How to Remove Desktop icons and Widgets?
A. Press and Hold the icon or widget. The phone will vibrate and on the bottom of the phone you will see anoption to remove. While still holding the icon or widget drag it to the remove button. Once remove turns red drop the item and it is gone
13. Describe a real time scenario where android can be used?
A .Imagine a situation that you are in a country where no one understands the language you speak and you can
not read or write. However, you have mobile phone with you.
14. Is there a unique Android device ID?
A: Settings.Secure#ANDROID_ID returns the Android ID as an unique 64-bit hex string.
import android.provider.Settings.Secure;
private String android_id = Secure.getString(getContext().getContentResolver(),
Secure.ANDROID_ID);
15. What languages does Android support for application development?
A.Android applications are written using the Java programming language.
16. Describe Android Application Architecture?
A.Android Application Architecture has the following components:
• Services – like N
• Intent – To perform inter-communication network Operation between activities or services
• Resource Externalization – such as strings and graphics
• Notification signaling users – light, sound, icon, notification, dialog etc
17. What is the Android Open Source Project?
A. We use the phrase “Android Open Source Project” or “AOSP” to refer to the people, the processes, and the source code that make up Android.
18. Why did we open the Android source code?
A .Google started the Android project in response to our own experiences launching mobile apps. We wanted to make sure that there would always be an open platform available for carriers, OEMs, and developers to use to make their innovative ideas a reality. We also wanted to make sure that there was no central point of failure, so that no single industry player could restrict or control the innovations of any other. The single most important goal of the Android Open-Source Project (AOSP) is to make sure that the open-source Android software is implemented as widely and compatibly as possible, to everyone’s benefit.
19. What is a ContentProvider and what is it typically used for?
A: ContentProvider manages access to a structured set of data. It encapsulates the data and provide mechanisms for defining data security. ContentProvider is the standard interface that connects data in one process with code running in another process.
20. When does onResume() method called?
A: onResume() method is an activity lifecycle method. This is called when the activity come to foreground. You can override this method in your activity to execute code when activity is started, restarted or comes to foreground.
21. Will it work on my phone?
A.The app will work on all phones and tablets running Android version 1.6 and above.
22. How much does it cost?
A.The app is free and ad-supported.
23. How do I save the app to my SD card?
A. From the device's Settings menu, go to Applications > Manage applications > The Guardian. Under the data
header, choose "Move to SD card".
24. What is the use of WebView in android?
A : WebView is an android UI component that displays webpages. It can either display a remote webpage or can also load static HTML data. This encompasses the functionality of a browser that can be integrated to application. WebView uses the WebKit rendering engine to display web pages and includes methods to navigate forward and backward through a history, zoom in and out, etc.
25. How to get screen dimensions in pixels in Andorid Devices?
A: int screenHeight = getResources().getDisplayMetrics().heightPixels;
int screenWidth = getResources().getDisplayMetrics().widthPixels;
26. What is Mono for Android?
A. Mono for Android is a software development kit that allows developers to use the C# language to create mobile applications for Android-based devices.Mono for Android exposes two sets of APIs, the core .NET APIs that C# developers are familiar with as well as a C# binding to Android's native APIs exposed through the Mono.Android.* namespace.You can use Mono for Android to develop applications that are distributed through the Android Application Stores or to deploy software to your personal hardware or the Android simulator.
27. Difference between Activity Context and Application Context?
A:They are both instances of Context, but the application instance is tied to the lifecycle of the application, while the Activity instance is tied to the lifecycle of an Activity. Thus, they have access to different information about the application environment.
If you read the docs at getApplicationContext it notes that you should only use this if you need a context whose lifecycle is separate from the current context.
28. What is the difference between a fragment and an activity? Explain the relationship between the two?
A:An activity is typically a single, focused operation that a user can perform (such as dial a number, take a picture, send an email, view a map, etc.). Yet at the same time, there is nothing that precludes a developer from creating an activity that is arbitrarily complex.
Activity implementations can optionally make use of the Fragment class for purposes such as producing more modular code, building more sophisticated user interfaces for larger screens, helping scale applications between small and large screens, and so on. Multiple fragments can be combined within a single activity and, conversely, the same fragment can often be reused across multiple activities. This structure is largely intended to foster code reuse and facilitate economies of scale.
A fragment is essentially a modular section of an activity, with its own lifecycle and input events, and which can be added or removed at will. It is important to remember, though, that a fragment’s lifecycle is directly affected by its host activity’s lifecycle; i.e., when the activity is paused, so are all fragments in it, and when the activity is destroyed, so are all of its fragments.
29. What is 'Context' on Android?
A: Context of current state of the application/object. It lets newly-created objects understand what has been going on. Typically you call it to get information regarding another part of your program (activity and package/application).
You can get the context by invoking getApplicationContext(), getContext(), getBaseContext() or this (when in the activity class).
30. Where is the UI Designer?
A. Mono for Android does not bundle a UI designer to create the UI XML files We do not provide an
integrated UI designer in Mono for Android 1.0. No decisions past that have been made. We will be listening to user feedback to decide where to put resources for the future versions.
31. What is the difference between Service and IntentService? How is each used?
A: Service is the base class for Android services that can be extended to create any service. A class that directly extends Service runs on the main thread so it will block the UI (if there is one) and should therefore either be used only for short tasks or should make use of other threads for longer tasks.
IntentService is a subclass of Service that handles asynchronous requests (expressed as “Intents”) on demand. Clients send requests through startService(Intent) calls. The service is started as needed, handles each Intent in turn using a worker thread, and stops itself when it runs out of work. Writing an IntentService can be quite simple; just extend the IntentService class and override the onHandleIntent(Intent intent) method where you can manage all incoming requests.
32. What is the API profile exposed by Mono for Android?
A. Mono for Android uses the same API profile for the core libraries as MonoTouch.Specifically, MonoTouch and Mono for Android both support a Silverlight-based API, without Silverlight's UI libraries (e.g. no XML, no WindowsBase.dll, etc.), and free of the sandboxing limitations of Silverlight.
33. Are the Android releases available in a ROM?
A. No, Android is not yet available in a ROM format.Currently Android is installed by using a clean SD Card, and booted from there.It is booted by running a special application called 'Haret.exe' residing on your SD Card which will terminate the Windows kernel and boot into Linux/Android.It can't easily be run from ROM because a) it's too experimental to risk putting in ROM and then killing a device and b) WinMo does some hardware initialization that isn't documented, but is needed before Android can run.
34. When will it be available in a ROM?
A. No time soon. Folks are working on it, but you'll need a lot of patience before it (if ever) arrives
35. How do I turn off, or reboot Android?
A. In earlier releases, you had to pull the battery or press the reset button, in newer releases, you can hold down the 'end call' button and see a menu.
36. What is DDMS? Describe some of its capabilities.
A: DDMS is the Dalvik Debug Monitor Server that ships with Android. It provides a wide array of debugging features including:
- port-forwarding services
- screen capture
- thread and heap information
- network traffic tracking
- incoming call and SMS spoofing
- simulating network state, speed, and latency
- location data spoofing
37. What if my app uses location API, and service provider shuts that off, can they?
A. They can do that... it’s not a perfect world. Rather than having us dictate what carriers and OEMs support,
we let developers develop killer apps that will require it.
We want to ensure all the application development that goes on for Android... we want to give OEMs an
incentive to keep things open. It’s a positive, self fulfilling vision.
38.If I’m a game developer and I’m building piece of content and I want to sell it, how do I do that and realize revenue?
A. Content distribution — we’ve thought of that. It’d be great if there were a place where people could go to
safely download and pay for content.
39. We use SMS interception for system signalling. Is there a mechanism for an app to respond and stop the signaling chain? Is there security around that so that one vendor can’t hijack a message and respond to it?
A. There’s a mechanism where an application can register to receive a message with a certain signature and
prevent others from getting it. We have a system of permissions apps are able to declare, enforce, and require to
perform certain operations. Things like dial the phone, get to contacts, etc.. But these aren’t things that are
baked in the core of the system. An arbitrary app could declare custom permissions.
As far as restricting another app, the model we’ve been going by... the phone is not controlled by the
application vendor, it’s controlled by the user. Whether or not the permissions are granted is up to the user that
owns the phone. If you created a protocol that intercepts an SMS and another party wrote an app that intercepts
the same SMS and the user wants to use that, the user could be free to stick that in.
40. Can the user set a priority?
A. Don’t know, post your question to the developer’s community board.
41. Which of the code snippets below is the correct way to check if a Compass sensor is present on the system? Explain your answer.
Answer 1:
PackageManager m = getPackageManager();
if (!m.hasSystemFeature(PackageManager.FEATURE_SENSOR_COMPASS)) {
// This device does not have a compass, turn off the compass feature
}
Answer 2:
SensorManager m = getSensorManager();
if (!m.hasSystemFeature(SensorManager.FEATURE_SENSOR_COMPASS)) {
// This device does not have a compass, turn off the compass feature
}
Answer 3:
Sensor s = getSensor();
if (!s.hasSystemFeature(Sensor.FEATURE_SENSOR_COMPASS)) {
// This device does not have a compass, turn off the compass feature
}
42. What’s so special about Android?
A. Unlike the proprietary iPhone operating system (now known as "iOS,"), which is under the complete control of Apple — and the same goes for Research in Motion’s BlackBerry OS or Microsoft’s Windows Phone platform — Google released Android as an open-source OS under the auspices of the Open Handset Alliance,leaving phone manufacturers (relatively) free to tweak Android as they see fit for a given handset.
That’s one thing that’s special about Android. Another thing is that it just happens to be a really good OS, the first one in the post-iPhone wireless era to really give Apple a run for its money. Android may not be as sleek or polished as iOS (that’s my humble opinion, at least), but it’s fast and powerful, with an intuitive user interface that’s packed with options and flexibility. It’s also being constantly improved courtesy of the big brains at Google, making the Android experience sleeker by the day.
43. What is a portable wi-fi hotspot?
A:The portable wi-fi hotspot is used to share internet connection to other wireless devices.
44. What is NDK?
A. NDK stands for Native Development Kit. By using NDK, you can develop a part of app using native language such as C/C++ to boost the performance.
45. What is needed to make a multiple choice list with a custom view for each row?
A. Multiple choice list can be viewed by making the CheckBox android:id value be “@android:id /text1″. That is the ID used by Android for the CheckedTextView in simple_list_item_multiple_choice.
46. What are the life cycle methods of android activity?
A:There are 7 life-cycle methods of activity. They are as follows:
onCreate()
onStart()
onResume()
onPause()
onStop()
onRestart()
onDestroy()
47. Difference between px, sp, dip, dpi and pt in Android?
A: px is one pixel. px is corresponds to actual pixels on the screen.
sp is scale-independent pixels. SP is like the dp unit, but it is also scaled by the user's font size preference.
dip is Density-independent pixels.
dpi is Dots per inches.
pt is points.
48. What are the approaches required to share persistent user-defined objects?
A: Persistent objects come when there is process that is in the running state and the system can perform any action like restart or kill. If there is any data that will persist and required from another data then it is very essential to save it and share it so that if one activity is down, another activity can be performed without any hindrance. To share the complex persistent user-defined objects, it is required to have the approaches like:
- Application preferences: that is used to allow the user to change the setting of preferences and make it accessible by some other objects.
- Files: permissions on the files can be set so that any other file can also use and share the objects
- Content providers: allow easy to follow patterns that allow the user to select the object and share it with other functions.
- Database: the database can be used to store the user data and can easily link between the user and the entity that are present in it.
49.What are containers?
A: Containers holds objects and
widgets together, depending on which items are needed and in what
arrangement they need to be in. Containers may hold labels, fields,
buttons, or even child containers, as examples.
50.What are App Widgets?
A: Also referred to simply as Widgets,
App Widgets in the Android world are miniature views that are
embedded within Android apps and typically display periodic updates.
Music players, weather updates, sports scores, and stock price
changes are all examples of data that can be displayed in an App
Widget.
51. How will you record a phone call in Android? How to get a handle on Audio Stream for a call in Android?
A. Permissions.PROCESS_OUTGOING_CALLS: Allows an application to monitor, modify, or abort outgoing
calls.
52. Why cannot you run standard Java bytecode on Android?
A. Android uses Dalvik Virtual Machine (DVM) which requires a special bytecode. We need to convert Java
class files into Dalvik Executable files using an Android tool called "dx". In normal circumstances, developers
will not be using this tool directly and build tools will care for the generation of DVM compatible files.
53. Can you deploy executable JARs on Android? Which packaging is supported by Android?
A. No. Android platform does not support JAR deployments. Applications are packed into Android Package
(.apk) using Android Asset Packaging Tool (aapt) and then deployed on to Android platform. Google provides
Android Development Tools for Eclipse that can be used to generate Android Package.
54. Does android support other language than java?
A:Yes, android app can be developed in C/C++ also using android NDK (Native Development Kit). It makes the performance faster. It should be used with android SDK.
55. What is an action?
A. The Intent Sender desires something or doing some task
56. What are Dalvik Executable files?
A. Dalvik Executable files have .dex extension and are zipped into a single .apk file on the device.
57. How does Android system track the applications?
A. Android system assigns each application a unique ID that is called Linux user ID. This ID is used to track
each application.
58. When does Android start and end an application process?
A. Android starts an application process when application's component needs to be executed. It then closes the
process when it's no longer needed (garbage collection).
59. How can two Android applications share same Linux user ID and share same VM?
A. The applications must sign with the same certificate in order to share same Linux user ID and share same
VM.
60. Write code snippet to retrieve IMEI number of Android phone.
A. TelephonyManager class can be used to get the IMEI number. It provides access to information about the telephony services on the device.
Code
TelephonyManager mTelephonyMgr = (TelephonyManager)
getSystemService(Context.TELEPHONY_SERVICE);
String imei = mTelephonyMgr.getDeviceId();
A. You can download the GoToMeetng app from the Android Market by signing in to your Google account
linked with your Android device and searching for the GoToMeeting app to install it. If you don’t see an Install
button, you may not be running Android 2.2 or higher – the minimum system requirement needed to install the
GoToMeeting app.
You can also download the GoToMeeting app from the Amazon Appstore (only available in the U.S.), which
lets you instantly download the GoToMeeting app to an Android device.
If you have the GoToMeeting app pre-loaded onto your device, you’ll need to first upgrade to the latest version
of GoToMeeting. To upgrade, select the GoToMeeting daisy icon and then select the Upgrade button to install
the most recent version of the app.
62.If I have a Motorola Android-based device that doesn’t have the Android Market app, can I still
download the GoToMeeting app?
A.Yes. Attendees using Motorola Android-based devices in China can now download the GoToMeeting app
from SHOP4APPSTM – Motorola’s preinstalled Android application storefront. The GoToMeeting app is not yet
localized in Chinese, but it is available in English, German, French, Spanish and Italian.
63.Is there a way to run Python on Android?
A:One way is to use Kivy:
- Open source Python library for rapid development of applications that make use of innovative user interfaces, such as multi-touch apps.
- Kivy runs on Linux, Windows, OS X, Android and iOS. You can run the same [python] code on all supported platforms.
64. How you can use built-in Messaging within your application?
A: You can use an Intent object to activate the built-in Messaging service. You have to pass MIME type “vnd.android-dir/mms-sms”, in setType method of Intent as shown in the following given below code.
Intent intent = new Intent (android.content.Intent.ACTION_VIEW);
intent.putExtra("address", "5556; 5558;");// Send the message to multiple recipient.
itent.putExtra("sms_body", "Hello my friends!");
intent.setType("vnd.android-dir/mms-sms");
startActivity(intent);
65. Does Android support Adobe Flash in the browser?
A.Flash support varies by device with Android 2.1. The Samsung Acclaim does not have Flash support upon
launch, but the HTC Desire will support Flash Lite 4.0 running Android 2.1. Flash 10.1 support is coming to
Android-powered phones with Android 2.2.
66.Does Android support push email or is it pull?
A. Android 2.1 supports push e-mail for Exchange mail and Gmail.
67. Will these phones have world phone capabilities, with the ability to make calls, receive data in other countries? Or will they be able to use Google Voice to make calls?
A.Our Android-powered phones have Wi-Fi which can be used abroad for data, including Google Voice for
making international calls. International Roaming for voice is available in several countries.
68. Will the App run on my Android phone?
A. Yes, our App is fully compatible with any Android phone running Android software v2.1 or later.
69. How do I install your App?
A. You can install our App from the Android Market by following the below steps:
Open the Android Market application in the Applications menu.
Hit the search icon and type in E.ON
To install it, hit the ‘Free’ button on the left hand side
In the next screen, it will give you more details about the application including the different functionalities it
will need to access. Just click on OK to finish installing the application.
70. How do I find and download updates to the E.ON Android application?
A. Any updates to our App will appear on your notification menu at the top of your screen. Just tap on the E. App icon and you'll be taken into the Android Market and be presented with the E.ON App download page.
71. What is a service in android?
The Service is like as an activity to do background functionalities without UI interaction.
72. What is an Intent?
A class (Intent) which describes what a caller desires to do. The caller will send this intent to Android's intent
resolver, which finds the most suitable activity for the intent. E.g. opening a PDF document is an intent, and the
Adobe Reader apps will be the perfect activity for that intent (class).
73. What is a Sticky Intent?
A. Sticky Intent is also a type of Intent which allows a communication between a function and a service
sendStickyBroadcast() performs a sendBroadcast(Intent) known as sticky, i.e. the Intent you are sending stays
around after the broadcast is complete, so that others can quickly retrieve that data through the return value of
registerReceiver(BroadcastReceiver, IntentFilter). In all other ways, this behaves the same as
sendBroadcast(Intent). One example of a sticky broadcast sent via the operating system is
ACTION_BATTERY_CHANGED. When you call registerReceiver() for that action -- even with a null
BroadcastReceiver -- you get the Intent that was last broadcast for that action. Hence, you can use this to find
the state of the battery without necessarily registering for all future state changes in the battery.
74. How the nine-patch Image different from a regular bitmap? Alternatively, what is the difference between nine-patch Image vs regular Bitmap Image?
A.It is one of a resizable bitmap resource which is being used as backgrounds or other images on the device.
The NinePatch class allows drawing a bitmap in nine sections. The four corners are unscaled; the middle of the
image is scaled in both axes, the four edges are scaled into one axis.
75. What is a resource?
A. user defined JSON, XML, bitmap, or other file, injected into the application build process, which can later be
loaded from code.
76.How will you record a phone call in Android? or How to handle an Audio Stream for a call in Android?
Permission.PROCESS_OUTGOING_CALLS: Will Allow an application to monitor, modify, or abort outgoing
calls. So using that permission we can monitor the Phone calls.
77.Does Android support the Bluetooth serial port profile?
Yes.
78. Can an application be started on powerup?
Yes.
79. How to Translate in Android?
The Google translator translates the data of one language into another language by using XMPP to transmit
data. You can type the message in English and select the language which is understood by the citizens of the
country in order to reach the message to the citizens.
80. Describe Briefly the Android Application Architecture
Android Application Architecture has the following components:
Services like Network Operation
Intent - To perform inter-communication between activities or servicesResource Externalization - such as
strings and graphics
Notification signaling users - light, sound, icon, notification, dialog etc.
Content Providers - They share data between applications
81. What is needed to make a multiple choice list with a custom view for each row?
A. Multiple choice list can be viewed by making the CheckBox android:id value be “@android:id /text1". That
is the ID used by Android for the CheckedTextView in simple_list_item_multiple_choice.
82. What dialog boxes are supported in Android ?Android supports 4 dialog boxes:
AlertDialog: An alert dialog box supports 0 to 3 buttons and a list of selectable elements, including
check boxes and radio buttons. Among the other dialog boxes, the most suggested dialog box is the alert
dialog box.
ProgressDialog: This dialog box displays a progress wheel or a progress bar. It is an extension of
AlertDialog and supports adding buttons.
DatePickerDialog: This dialog box is used for selecting a date by the user.
TimePickerDialog: This dialog box is used for selecting time by the user.
83.What are the notifications available in android?
A:
Toast Notification − It will show a pop up message on the surface of the window
Status Bar Notification − It will show notifications on status bar
Dialogue Notification − It is an activity related notification.
84.Features of Android:
Application framework enabling reuse and replacement of components
Dalvik virtual machine optimized for mobile devices
Integrated browser based on the open source WebKit engine
Optimized graphics powered by a custom 2D graphics library; 3D graphics based on the OpenGL ES 1.0
specification (hardware acceleration optional)
SQLite for structured data storage
Media support for common audio, video, and still image formats (MPEG4, H.264, MP3, AAC, AMR, JPG,PNG, GIF)
GSM Telephony (hardware dependent)
Bluetooth, EDGE, 3G, and WiFi (hardware dependent)
Camera, GPS, compass, and accelerometer (hardware dependent)
Rich development environment including a device emulator, tools for debugging, memory and performance
profiling, and a plugin for the Eclipse IDE.
85.What is an Application ?A. Collection of one or more activities, services, listeners, and intent receivers. An application has a single
manifest, and is compiled into a single .apk file on the device.
86.What is a Content Provider ?
A. A class built on ContentProvider that handles content query strings of a specific format to return data in a
specific format. See Reading and writing data to a content provider for information on using content providers.
87. What is a Dalvik ?
A. The name of Android’s virtual machine. The Dalvik VM is an interpreter-only virtual machine that executes
files in the Dalvik Executable (.dex) format, a format that is optimized for efficient storage and memory-
mappable execution. The virtual machine is register-based, and it can run classes compiled by a Java language
compiler that have been transformed into its native format using the included “dx” tool. The VM runs on top of
Posix-compliant operating systems, which it relies on for underlying functionality (such as threading and low
level memory management). The Dalvik core class library is intended to provide a familiar development base
for those used to programming with Java Standard Edition, but it is geared specifically to the needs of a small
mobile device.
88.What is an DDMS ?
A. Dalvik Debug Monitor Service, a GUI debugging application shipped with the SDK. It provides screen
capture, log dump, and process examination capabilities.
89.What is Drawable?
A. A compiled visual resource that can be used as a background, title, or other part of the screen. It is compiled
into an android.graphics.drawable subclass.
90.What are fragments in Android Activity ?
A. Fragment represents a behavior or a portion of user interface in an Activity. And it is a self-contained
component with its own UI and lifecycle.
91. What is Service?
A. Service doesn't have a visual user interface , but rather runs in the background for an indefinite period of
time. For Example, a service might play background for music as the user attends to other matters.
92. What is BroadReceivers?
A. BroadcastReceiver is a component that does nothing but receive and react to broadcast announcements.
For example, the battery is low or that the user changed a language preference.
93.How do you avoid an ANR?
A: A follow-up to the previous
question, there are a number of possible answers here. What you want
to hear is that you want as little work done as possible on the main
thread, also known as the “UI thread”. Since that is the core
single thread that your application runs on, you would want to keep
activities that require more complex computations or network and
database connections, for example, on separate worker threads so as
not to slow down the main thread.
94.How many ways data stored in Android?
1.SharedPreferences
2.Internal Storage
3.External Storage
4.SQLite Database
5.Network connection
95. Types of Android applications?
1.Foreground
2.Background
3.Intermittent
4.Widget
96. Android Development Tools?
A. The Android SDK and Virtual Device Manager Used to create and manage Android Virtual Devices (AVD)
and SDK packages.
The Android Emulator An implementation of the Android virtual machine designed to run within a virtual
device on your development computer. Use the emulator to test and debug your Android applications.
Dalvik Debug Monitoring Service(DDMS) Use the DDMS perspective to monitor and control the Dalvik virtual
machines on which your debugging your application.
Android Asset Packaging Tool(AAPT) Constructs the destributable Android packages files (.apk).
Android Debug Bridge(ADB) A client-server application that provedes a link to a running emulator.It lets you
copy files, install compiled application packages(.apk),and run shell commands.
97.What is View in Android?
A. Views are the base class for all visual interface elements(commonly known as controls or widgets).
All UI controls,including the layout classes,are derived for View.
98. What View Group in Android?
A. View Groups are extensions of the View class that can contain multiple child View.Extend the ViewGroupclass to create compound controls made up of interconnected child Views.
99.What information do you need before you
begin coding an Android app for a client?
A: You want to find out that this
person will seek to truly understand what you are trying to
accomplish with your app, and the functionality. The following items
are good to hear:
-
Objective statement or purpose of the app for the app publisher
-
Description of the target audience or user demographics
-
Any existing apps that it might be similar to
-
Wireframes
-
Artwork;
A: They're the same thing (in API Level 8+). Use match_parent.
FILL_PARENT (renamed MATCH_PARENT in API Level 8 and higher), which means that the view wants to be as big as its parent (minus padding)
fill_parent: The view should be as big as its parent (minus padding). This constant is deprecated starting from API Level 8 and is replaced by match_parent
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It is also include above, some are missing please don't forget to solve this also:
- What is Activity?
-
Activity life cycle? (Example when app come from background to foreground which method get called?)
-
What is Fragment?
-
Fragment life cycle?
-
Interface and it's importance?
-
Application State and how does it save data during your app session?
-
What are benefit of Shared preference?
-
Services in Android?
-
How to make list view scroll smoothly? ( e.g Viewholder pattern.. )
-
What layout does paytm use mainly? (Linear or Relative, Of course Relative layout)
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Difference between Thread and Handler?
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Asynchronous Task and Threads?
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Sqlite and content provider?
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Polymorphism?
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Inheritance?
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Difference between Interface and Abstract Class?
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Synchronized this keyword meaning?
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Hashmap and LinkedHaspmap and dynamic array?
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Bundle?
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How does HttpRequest for calling an API from server, works ?
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BroadCastReceiver?
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Frame layout?
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Horizontal and Vertical Scroll?
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Tab layout?
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View pager?
Happy Coding !!!
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