Android Interview Questions and Answers
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Best Android Interview Questions and Answers
As people nowadays use smartphones to the maximum, the need for Android developers is also emerging. Most of the IT sectors in the recent days are looking for professional developers to create feature-rich applications which might improve their business growth and bring in more valuable customers. And, so aspirants who have chose Android as their field of interest will certainly experience more career opportunities with attractive pay scale in the near future. Also, android developers are getting highly paid as their importance is evolving day by day.
Here, you will find top 50 Android Interview Questions and Answers. Candidates who are preparing to attend Android interviews can make use of these top 50 Android Interview Questions and Answers. All these Android interview questions are prepared in consultation with the top recruiters and all these top 50 Android Interview Questions and Answers are frequently asked by the employers to check the skill of the candidates. So do not miss preparing these questions to brush up your Android skill before attending the interview. We wish you all success in your career excellence.
Top Android Interview Questions and Answers
Android can be defined as the following:
- Android is nothing but an open-source Linux-based operating system established in smartphones and tablets.
- Android supports kernel system which makes it simpler for the developers to design and deploy apps as per their preference.
The current Android version is named as Android Pie or it can also be known as Android 9.0. The current Android version was launched in August, 2018.
Android Name | Version | Year of Release |
Android 1.5 | Android Cupcake | 2009 |
Android 1.6 | Android Donut | 2009 |
Android 2.0 – 2.1 | Android Éclair | 2009 |
Android 2.2 – 2.2.3 | Android Froyo | 2010 |
Android 2.3 – 2.3.7 | Android Gingerbread | 2010 |
Android 3.0 – 3.2.6 | Android Honeycomb | 2011 |
Android 4.0 – 4.0.4 | Android Ice Cream Sandwich | 2011 |
Android 4.1 – 4.3.1 | Android Jelly Bean | 2012 |
Android 4.4 – 4.4.4 | Android KitKat | 2013 |
Android 5.0 – 5.1.1 | Android Lollipop | 2014 |
Android 6.0 – 6.0.1 | Android Marshmallow | 2015 |
Android 7.0 – 7.1.2 | Android Nougat | 2016 |
Android 8.0 – 8.1 | Android Oreo | 2017 |
Android 9.0 | Android Pie | 2018 |
A self-contained, open-source and serverless database known as SQLite is by default embedded in Android.
The Android application architecture comprises the following:
- Android Framework
- Android Applications
- Linux Kernel
- Libraries
Yes, you can probably change the name of the application after deploying but you may experience issues with some of the application functionalities.
An Android App can be developed with the help of the below-mentioned tools:
- JDK
- SDK Tools
- Eclipse + ADT Plugin
Android has some of the special advantages which are listed below:
- It’s both free and open-source
- It supports all Windows, MAC and Linux as it is platform-independent
- It is compatible with various technologies like cameras, Bluetooth, Wi-Fi, speech and more
- It makes use of an advanced and highly optimized virtual machine called DVM (Dalvik Virtual Machine)
Java is the programming language which is highly preferred by Android, apart from this C/C++ can also be used; it actually performs faster and better in Android SDK.
No, standard Java bytecode cannot be executed or run on Android as Android solely uses DVM also known as Dalvik Virtual Machine. It requires only special bytecodes to perform well. In this manner, using ‘dx’ an Android tool, we will have to convert all the Java class files into Dalvik executable files. Mostly Android developers will not prefer this tool, as the DVM compatible file conversion will be carried out by the in-build tools.
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Android SDK is nothing but a set of tools used by Android developers to create, develop and write apps at ease. Android SDK also consists of a graphical interface that effectively emulates an Android driven handheld environment which allows developers to easily create, test, and debug their development codes easily.
Some of the tools associated with Android SDK are as follows:
- Dalvik Debug Monitoring Services
- Android Emulator
- Android Asset Packaging Tool
- Android Debug Bridge
Some of the special characteristics of Android are as follows:
- It is an open source
- It supports multiple versions of OS and various interoperability functions
- It can be customized to a huge extent
AIDL is known as Android Interface Definition Language and it can be used to handle the interface requirements among clients and the service to communicate at the same level with the help of interprocess communication. The data types supported by AIDL are as follows:
- String
- List
- Map
- CharSequence
- Native Java data types (int, long, char and Boolean)
Android framework is a collection of APIs that allows developers to develop apps and it contains the following:
- Intent
- Activities
- Content Providers
- Others
Intent is nothing but a simple message that is distributed between the components and it’s an intention to execute an action. Actually, intent requests particular and specific actions from various components which might include opening a web page, sending an email or launching a specific set of activity. Implicit intent and explicit intent are the two types of intent.
Whenever users perform an action, implicit intent can be used. Some of the examples of implicit intent can be send SMS, email, dial a number or Uri can be used to specify a particular data type.
Explicit intent is the process where users switch from one activity to another which can also be referred to as a target activity.
Action in Android is actually a description of something that is desired by an intent sender.
Syntax: <action android:name=”string” />
Found in: <intent-filter>
Listed below are some of the methods available to deliver intents among different components:
context.startActivity() – it is used to begin an activity
context.startService() – it is used to begin a service
context.sendBroadcast() – it is used to deliver a broadcast effectively
Context in Android defines an App’s current state. It can be used to create a new activity instance, to start a service, to access a database and more.
Sticky intent refers to a broadcast which makes use of the method called send sticky broadcast(). The intent actually sticks around the broadcast and lets the users to gather valuable information from it.
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Activities are the mobile app parts which can be easily viewed and interacted by the user. It is actually a Graphical User Interface (GUI) which denotes one Android Screen.
There are four essential activity states and they are as follows – Active, Paused, Stopped and Destroyed.
The three key loops available to monitor an activity are as follows:
- Entire lifetime
- Visible lifetime
- Foreground lifetime
Manifest file is where your activity should be declared.
Example:
<manifest></manifest>
<application></application>
<activity android:name=”.MyCourseJet”>
Content providers are used to cater relevant required information between several Android applications with which users can access required data present within an application at ease. Some of the examples of content providers are contact information, video, images and audio.
The others in Android framework refers to App widgets, processes and threads.
Android toast can be described as the following:
- Toast is actually a notification message that pops up on the window
- It covers only the space required for the pop up while the recent or current activity will remain active and users can interact with those activities
- This type of notification automatically fades in and out but it does not accepts or responds to any interaction events
Bundles in Android are used to distribute essential data to the sub folders.
findViewById is used to find or determine the view elements in an Android program.
APK is referred to as Android Packaging Kit. All the files present in Android packaging key are compressed into a single file known as the APK.
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Some of the Android exceptions are as follows:
- Inflate Exception
- OutOfResourceException
- BadSurfaceTypeException
- BadTokenException
Some of the major essential items found in every Android project are as follows:
- AndroidManifest.xml
- build.xml
- bin/
- src/
- res/
- assets/
There are four main dialogue boxes supported by Android and they are Alert dialog, Progress dialog, Date picker dialog and Time picker dialog.
The layouts are placed in the layouts folder in the form of XML files.
ANR stands for Application Not Responding, it’s a notification or a pop up message that triggers when an application undergoes extended lag time as it involves various functionalities and is being executed simultaneously by the user.
ADB stands for Android Debug Bridge which is a tool present in SDK. It is actually a command-line tool which can be to communicate between several emulator instances.
Mobile testing is specially performed on the mobile devices to test the mobile features which include SMS, contacts, browsers and the calling functionalities while mobile application testing is performed on the apps to test the functions and the features of the apps that are being installed in the mobile device.
AAPT stands for Android Asset Packaging Tool which allows the developers to perform well with the zip-compatible devices which may include creation, content viewing and extraction.
If an Android application is crashing frequently, then these steps are the best ways to fix the issue:
- The problem might be with the memory space, check whether you have enough and sufficient memory space
- Under the “Application Manager” menu, go to “settings” and then clear all the app data by choosing “clear cache memory”
- Tinker with the appropriate memory management features as every app do not perform on the similar assorted machines
- Check whether the apps that you prefer is compatible with the device that you are using
9-patch image can be described as a resizable bitmap resource which can be utilized on the device as a background or relevant images. It can allow users to sketch bitmap in almost 9 sections. The extension for 9-patch image will be .9.png. The extension can also be in 9 ways like 4 unscaled corners, 4 scaled corners and 1 axis whereas the middle one can be scaled as both the axes as preferred.
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In order to share similar Linux user ID and the Virtual Machine (VM) among the two Android applications both the applications must be signed in with the same identical certificate.
No, actually Android platform does not support or it is not compatible to deploy executable JARs.
Broadcast receivers can be explained as below:
- Broadcast receivers are a mechanism with which the host applications can listen to the system level events at ease.
- Applications also make use of broadcast receivers to perform actions that are related to the system level events like incoming calls, SMS and more.
- Broadcast receivers are also effective in maintaining a valid communication between applications and Android operating system.
Listed below are some of the storage methods found in Android:
- Shared preferences – it actually stores the private data primitives in key-value pairs
- Internal storage – it stores the private data on a particular device memory
- External storage – it stores the public data on a shared external storage
- SQLite Databases – it stores the structured data in a private database
A background process that is used to execute operations that are long-running is known as a service in Android.
There are two types of services found in Android and they are local and remote.
Service | Thread |
It is similar to an Activity but it does not have any interface | A concurrent unit of execution is termed as thread |
When an application is killed, the service will be running and performing as before | When an application is killed, the thread will also be killed |
A sticky broadcast is actually used to communicate between several applications. These broadcasts are created without being notified to the user.
Escape character can be used as an attribute while preceded by double backslashes.
Orientation in Android actually represents the layout present in the rows and columns.
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