These days everyone is aware of android devices because it has a huge market all over the globe. Google the parent company of Android hire developers from across the world for further Android development. Even the Android which has an infinite number of Applications on its play store promising a bright future to the Android application developers.
Many tech companies even non-tech companies releasing their own Android applications to increase their reach in the market, having an android application become like having a website for your company. Like Google, its child Android is also dominating the smartphones market with more than 70% android user.
Android Interview Questions
Here in this article we have provided some top most important android related tech questions often asked during interviews.
Question: What is Android?
Answer: Android is an open-source Operating System used by touch screen mobile devices and tablets and it is based on Linux Kernel.
Question: Name the latest version of Android?
Answer: Pie Android 9.0 is the latest version of Android released in August 2018.
Question: Name all the Android version?
Answer: All Android versions are named alphabetically and on some dessert name.
|Android Version||Android Name||Release|
|7.0 – 7.1.2||Nougat||2016|
|6.0 – 6.0.1||Marshmallow||2015|
|5.0 – 5.1.1||Lollipop||2014|
|4.4 – 4.4.4||KitKat||2013|
|4.1 – 4.3.1||Jelly Bean||2012|
|4.0 – 4.0.4||Ice Cream Sandwich||2011|
|3.0 – 3.2.6||Honeycomb||2011|
|2.3 – 2.3.7||Gingerbread||2010|
|2.2 – 2.2.3||Froyo||1010|
Question: What is the Android SDK?
Answer: Android SDK (Software Development tool) is a tool used by the Android developers to create an application for the android platform, basically, it is used to emulate an Android environment. This is a very handy tool you can test how would your application run on Android mobile devices.
Question: Name the Android application components.
- Resource Externalization
- Content Provider
Question: Give some Advantages of Android.
- It is an open source platform
- Platform independent
- It supports various plugin the like camera, Bluetooth, Wi-Fi, speech recognition and lots more
- Highly Optimized Virtual Machines
Question: Which Programming languages Android supports?
Answer: In 2019 Google has announced Kotlin as its Official language for Android development before that there was no official language for Android and developers would use Java to develop Android application. Android support both Java and Kotlin.
Question: What is .APK?
Answer: .APK (Android Application Package) which is also known as the android app file extension, it is a compressed file format which contains all application code, resource files, certification and other files. All the application files are compressed in once so that it is easy to distribute and install.
Question: What is an Activity?
Answer: An activity is defined as the GUI of a single screen which performs an action on the screen, a complete application is made up of many activities. For example, if we have created an email application so its inbox interface would be an activity and its Draft interface would be another.
Question: Name all the Android Architecture layers.
- Linux Kernel
- Android Libraries
- Android Runtime
- Application Framework
Question: What does the Application Framework do in Android Architecture?
Answer: It is one the most important layer of Android architecture which provides many high-level services to the application in the form of Java Classes some of these services are Activity manager, Content Provider, Resource Manager, Notification Manager, View System and lots more.
Question: Why can’t we run Java byte code on Android?
Answer: Android have DVM (Dalvik Virtual Machine) not JVM (Java Virtual Machine) and to run Java Byte code we need JVM
Question: Name the lifecycle of Activities.
- OnCreate(): When the activity is created with the first interface.
- OnStart(): it summoned when the activity gets visible to the user.
- Onresume(): when user interacts with the activity this method is called
- Onpause(): when activity is running in the background
- OnStop(): when activity is hidden from the user
- OnDestroy(): when we need to terminate the activity.
- OnStart(): it stops the activity and brings back to the stat activity.
Question: What happens to the activity when a user rotates the screen?
Answer: When the user rotates the screen the instance of the current activity gets terminated and a new instance gets created simultaneously.
Question: What is intent in Android?
Answer: Intent aka intention which is used to perform actions. It is an object that sends message to the other components of the application and request for some action.
There are two types of Intent:
- Implicit Intent
- Explicit intent
Question: What is the different between Implicit and Explicit intent?
Answer: Implicit intent used when a user performs an action, for example, send a message, dial a number on the dial pad
Explicit helps the user to move from one activity to the another.
Question: What is the difference between the File, Class and Activity in Android?
Answer: The file is used to store information.
Class is used to hold functionality and it compiled from the java source file so the android uses its functionality.
Activity, on the other hand, is a view or a user interface, so a user can also avail the class functionality.
Question: What are the containers?
Answer: Containers, as the name itself implies, holds objects and widgets together, depending on which specific items are needed and in what particular arrangement that is wanted. Containers may hold labels, fields, buttons, or even child containers, as examples.
Question: Name the tools are in Google SDK.
- Android Emulator
- DDMS – Dalvik Debug Monitoring Services.
- AAPT- Android Assets Packaging tool.
- ADB- Android debug bridge.
Question: What is an ANR?
Answer: ANR stands for Application Not Responding, this is used when the application main activity does not respond for a while. It depends on some conditions like if there is no response to input after 5sec or the broadcast receiver is not done executing within 10 seconds.
Question: What is AAPT?
Answer: AAPT stands for Android Asset Packaging Tool, it helps the developer to handle zip-compatible archives, that can create, extract and view the contents.
Question: How we pass data to sub-activities?
Answer: We use HashMaps like structure such as Bundles to carry trivial data from one activity to its sub-activities.
Question: Why is WebView and why we use it in android?
Answer: WebView is a window or view which is used to show web pages inside an android application, it gives a browser look to the application. WebView uses WebKit rendering engine to display web pages and it also includes some navigation tools like forward, backward and history.
Question: What is Context?
Answer: Context is a class that handles the current state of the running application, it provides services like resolving resources, get access to the database and so on.
There are two types of Context
- Application Context
- Activity Context
Question: How can we clear the back stack of Activities when a new instance of an activity is called?
Answer: We can use the FLAG_ACTIVITY_CLEAR_TOP flag or FLAG_ACTIVITY_CLEAR_TASK and FLAG_ACTIVITY_NEW_TASK in conjunction
Question: Define Content Provide.
The content provider is used to providing data from one application to another when it requested. It manages the structured set of data and also provides data security.
Question: Name the different storage methods in Android.
- Shared Preferences
- Internal Storage
- External Storage
- SQLite Databases
Question: Can we run JAR on android?
Answer: No, but we can compress it into Android Package (.apk) with the help of Asset Packaging Tool (APT) and then run it on the Android platform.
Question: What is a Fragment?
Answer: A fragment is a modular form of activity and it can also be understood as a part of Activity which can combine with other fragments in a single activity which makes it reusable.
Question: What does Dalvik do in Android development?
Answer: Dalvik is a virtual machine in android which executes the code and runs the application it can also execute the multiple virtual machines.
Question: Give the difference between Service and Intent Service.
Answer: Android Service is used to perform the operation in the background such as playing music, though it does not provide any User interface.
Intent Service is used to handle asynchronous requests on demand.