In this technologically advanced era, there is an immense need for people to be knowledgeable about Android. There is a huge demand for the post of Android Developers and it pays well too. As a result, many people are eyeing for this job position. To help you with it, we have accumulated some good amount of interview questions which will help a lot of you job seekers.
1. What do you mean by Android?
Answer: Android is an open-source, Linux-based operating system used in mobiles, televisions, tablets, and other such applications.
2. Who is the founder of Android?
Answer: Andy Rubin is the founder of Android.
3. Explain the Android application Architecture.
Answer: Following is a list of components of Android application architecture:
- Services: Used to perform background functionalities.
- Intent: Used to perform the interconnection between activities and the data passing mechanism.
- Resource Externalization: strings and graphics.
- Notification: light, sound, icon, notification, dialog box and toast.
- Content Providers: It will share the data between applications.
4. State the advantages of Android?
Answer: Open-source: It means no license, distribution and development fee.
Highly optimized Virtual Machine: Android uses a highly optimized virtual machine for mobile devices, called DVM (Dalvik Virtual Machine).
Platform-independent: Windows, Mac, and Linux platforms supported.
Supports various technologies: It supports camera, Bluetooth, wifi, speech, EDGE, etc. technologies.
5. Does android support other languages than java?
Answer: Yes, an android app can be developed in C/C++ also using android NDK (Native Development Kit). It makes performance faster. It should be used with the Android SDK.
6. What is activity in Android?
Answer: Activity is like a frame or window in java that represents GUI. It represents one screen of android.
7. What is the intent?
Answer: It is a kind of message or information that is passed to the components. It is used to launch an activity, display a web page, send SMS, send an email, etc.
There are two types of intents in android:
- Implicit Intent
- Explicit Intent
8. How are the view elements identified in the android program?
Answer: View elements can be identified using the keyword findViewById.
9. Define Android toast.
Answer: An android toast provides feedback to the users about the operation being performed by them. It displays the message regarding the status of the operation initiated by the user
10. Explain the use of ‘bundle’ in android?
Answer: We use bundles to pass the required data to various subfolders.
11. What is an application resource file?
Answer: The files which can be injected for the building up of a process are called an application resource file.
12. What is the use of LINUX ID in android?
Answer: A unique Linux ID is assigned to each application in android. It is used for the tracking of a process.
13. Can the byte code be written in java be run on android?
Answer: No
14. What is a layout in Android?
Answer: A layout basically defines a structure which is visual by nature especially for a user interface such as an app widget or UI for an activity.
15. Define fragment.
Answer: The fragment is a part of Activity by which we can display multiple screens on one activity.
16. What is NDK?
Answer: NDK stands for Native Development Kit. If you have to use NDK, you would be able to develop a part of an app using native languages such as C/C++ to boost its performance.
17. What is ANR?
Answer: ANR stands for Application Not Responding. It is a dialog box that appears if the application is no longer responding.
18. What is the Google Android SDK?
Answer: The Google Android SDK is a toolset which is used by developers to write apps on Android-enabled devices. It contains a graphical interface that emulates an Android-driven handheld environment and allows them to test and debug their codes.
19. Which language does Android support to develop an application?
Answer: Android applications are written by using the java (Android SDK) and C/C++ (Android NDK).
20. What is ADT in Android?
Answer: ADT stands for Android Development Tool. It is used to develop the applications and test the applications.
21. What is View Group in Android?
Answer: View Group is a collection of views and other child views. It is an invisible part and the base class for layouts.
22. What is the Adapter in Android?
Answer: An adapter is used to create a child view to present the parent view items.
23. What is a nine-patch images tool in Android?
Answer: We can change bitmap images into nine sections with four corners, four edges, and an axis.
24. Which kernel is used in Android?
Answer: Android is a customized Linux 3.6 kernel.
25. What is application Widgets in Android?
Answer: Application widgets are miniature application views that can be embedded in other applications and receive periodic updates.
26. What is a singleton class in Android?
Answer: A singleton class is a class which can create only an object that can be shared by all other classes.
27 What is sleep mode in Android?
Answer: In sleep mode, CPU is slept and doesn’t accept any commands from android device except Radio interface layer and alarm.
28. What do you mean by a drawable folder in Android?
Answer: In Android, a drawable folder is compiled a visual resource that can use as a background, banners, icons, splash screen, etc.
29. What is a portable Wi-Fi hotspot?
Answer: The portable Wi-Fi hotspot is used to share the internet connection to other wireless devices.
30. What are the basic tools used to develop an Android app?
Answer: The basic tools that are used to develop an Android app are:
- JDK
- Eclipse+ADT plugin
- SDK Tools
31. Define Android Architecture.
Answer: The Android architecture consists of 4 components:
- Linux Kernel
- Libraries
- Android Framework
- Android Applications
32. What is a resource?
Answer: A resource can be said to be a user-supplied XML, bitmap, or any other file that is injected into the application build process, which can later be loaded from code.
33. What are the code names of android?
Answer:
- Aestro
- Blender
- Cupcake
- Donut
- Eclair
- Froyo
- Gingerbread
- Honeycomb
- Ice Cream Sandwich
- Jelly Bean
- KitKat
- Lollipop
- Marshmallow
34. Define Android application resource file?
Answer: As an android application developer, you’d be able to ingest files such as XML, JPEG, JSON, etc. into the build process and later on can load them from the code itself. These injected files that we talked about can be reversed as resources.
35. What are Dalvik practicable files?
Answer: Dalvik practicable files have .dex extension and that they are zipped into one .apk file on the device.
36. What is totally different information storage choices are accessible in Android?
Answer: Totally different information storage choices are accessible in the robot are:
– SharedPreferences
– SQLite
– ContentProvider
– File Storage
– Cloud Storage
37. What are the applications of SharedPreferences?
Answer: Following are the applications of SharedPreferences:
-Storing the data regarding the range of tourists (counter).
– Storing the date and time (when your Application is updated).
– Storing the username and parole.
– Storing user settings.
38. What are the key elements of robot Architecture?
Answer: Robot design consists of four of these key components:
– UNIX system Kernel
– Libraries
– Robot Framework
– Robot Applications
39. Tell North American country one thing regarding activityCreator?
Answer: –Associate in nursing activityCreator is the initial step for the creation of a brand new robot project.
– It consists of a shell script that is accustomed in such a way that we are in no way able to produce new filing system structure needed for writing codes in robot IDE.
40. Wherever are layout details placed? Why?
Answer: Layout details are placed in XML files are as follows:
– XML-based layouts give a {standardized|an identical|the same|a regular|an even} and standard means that of setting interface definition format.
41. What do containers hold?
Answer: – Containers hold objects and widgets in a very nominative arrangement.
– They’ll additionally hold labels, fields, buttons, or kid containers.
42. What’s the role of compatibility that’s utilized in Android?
Answer: The compatibility is outlined in terms of robot compatible devices that run any application. This application is written by third-party developers’ victimization the robot platform that comes within the variety of SDK and NDK.
– There are several filters that are accustomed to separate devices that are there to participate in the compatibility mode for the robot applications. The devices that are compatible need the robot to approve it for his or her trademark. The devices that don’t seem to pass the compatibility are simply given within the robot ASCII text file and may use the robot trademark.
– The compatibility could be a means through that the user will participate within the robot application platform. The ASCII text file is unengaged to use and it may be utilized by anyone.
43. What are the benefits of getting an Associate in nursing somebody among the robot environment?
Answer: The somebody permits the developers to figure around Associate in the nursing interface that acts as if it were Associate in the nursing actual mobile device.
– They’ll write, take a look at and write the code.
– They’re safe for testing the code in early style part.
44. What’s an exact Intent?
Answer: – express intent specifies the actual activity that ought to answer the intent.
– They’re used for application internal messages.
45. What’s Associate in Nursing Implicit Intent?
Answer: – just in case of Implicit Intent, Associate in nursing intent is simply declared.
– It’s for the platform to seek out Associate in a nursing activity that may answer it.
– Since the target element isn’t declared, it’s used for activating elements of different applications.
46. Where are the layout details placed? Why?
Answer: -Layout details are placed in XML files.
– XML-based layouts give a {standardized an identical the same|a regular|an even} and standard means that of setting interface definition format.
47. What do containers hold?
Answer: – Containers hold objects and widgets in a very nominative arrangement.
– They’ll additionally hold labels, fields, buttons, or kid containers.
48. What’s Orientation?
Answer: – Orientation decides if the LinearLayout ought to be conferred in row-wise or column-wise fashion.
– The values are set victimization setOrientation ()
– The values may be HORIZONTAL or VERTICAL
49. Tell North American country one thing regarding the nine-patch image.
Answer: – The Nine-patch within the image name refers to the means the image may be resized: four corners that are unscaled, four edges that are scaled in one axis, and also the middle one that may be scaled into each ax.
– A Nine-patch image permits resizing that may be used as background or different image size necessities for the target device.
50. How all the activities that are running run in the main thread?
Answer: All the applications that are running or may be accessed runs in the main thread of computer programmed by default. The modification may be done to form it run otherwise or to form it run or not in the slightest degree. The exception additionally comes process that the code handles the IPC calls that are coming back from different processes. The system accustomed maintain separate pools for all the processes and threads. One pool consists of the dealings threads that are in every method to dispatch all the incoming calls.
It additionally permits social calls to be handled in a very specialized manner. This permits the creation of separate threads that are used for long-running code, and to avoid the block of the most computer programmed threads. The services that run may be killed by the system if it’s going out of memory.
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