Mobile developer Interview Questions and answer. The tech industry is growing continuously and evolving day by day. New technologies and tools are being invented and are in use. This puts on a huge demand and supply gap amongst the sector of such developers and techies who are familiar with the trending and in demand technologies. And one such high demand skill is mobile development or mobile application development.
There are numerous tools which can help you become a good mobile application developer. For instance Flutter, React Native, Ionic, Xamarin, Felgo and many others. So if you are preparing to indulge into the mobile development arena and want to pursue a job in the same we are here to help. So, we have listed below some of the most frequently asked Mobile developer Interview Questions and answer.
1. What is a progressive web app?
The concept of the progressive web app (PWA) was approached by Google in late 2015. They are basically web applications (Website) but have look and feel like other native mobile apps. The progressive web app enabled websites can offer functionalities such as working offline, push notifications, and device hardware access.
2. Explain briefly about some of the major Andriod application components.
App components are the essential building blocks of an Android app. Each component is an entry point through which the system or a user can enter your app.
There are four different types of app components:
- Activities – An activity is the entry point for interacting with the user. It represents a single screen with a user interface.
- Services – A service is a general-purpose entry point for keeping an app running in the background for all kinds of reasons. It is a component that runs in the background to perform long-running operations or to perform work for remote processes.
- Broadcast receivers – A broadcast receiver is a component that enables the system to deliver events to the app outside of a regular user flow, allowing the app to respond to system-wide broadcast announcements.
- Content providers – A content provider manages a shared set of app data that you can store in the file system, in a SQLite database, on the web, or on any other persistent storage location that your app can access.
3. List some of the advantages of using native apps over hybrid apps.
- They work efficiently as they are built for that specific platforms
- Native apps are responsive on all the platform-specific devices
- They are very fast and the best in the app performance
- Native apps better integrate with mobile hardware
- They have interactive and intuitive User Interface (UI) and User Experience (UX) as per the user expectations based on specific platforms
- Some of the Native mobile apps work even without the Internet connection
- Native apps are secured and reliable
- They can easily access or utilize the other device-specific capabilities like GPS, Camera, Contacts, etc.
4. What is Android Data Binding?
The Data Binding Library is a support library that allows you to bind UI components in your layouts to data sources in your app using a declarative format rather than programmatically.
Layouts are often defined in activities with code that calls UI framework methods. The pros of using Android Data Binding:
- Reduces boilerplate code which in turns brings
- Less coupling
- Stronger readability
- Powerful, easy to implement custom attribute and custom view
- Even faster than findViewById – The binding does a single pass on the View hierarchy, extracting the Views with IDs. This mechanism can be faster than calling findViewById for several Views.
5. Explain in brief what is Xamarin?
Xamarin is a Cross Platform Mobile Development technology by Microsoft where we can develop the native app using the same code base across all platforms (iOS, Android, UWP) using the C# language. Xamarin uses two approaches for the app development:
- Xamarin.Forms and
- Xamarin Native.
Xamarin.Forms uses MVVM & XAML while Xamarin Native uses native UI technology and MVC or MVVMCross Architecture.
6. What is an Activity?
An Activity provides the window in which the app draws its UI.
This window typically fills the screen, but may be smaller than the screen and float on top of other windows. Generally, one activity implements one screen in an app. For instance, one of an app’s activities may implement a Preferences screen, while another activity implements a Select Photo screen.
7. Explain Activity lifecycle.
As a user navigates through, out of, and back to your app, the Activity instances in your app transition through different states in their lifecycle.
To navigate transitions between stages of the activity lifecycle, the Activity class provides a core set of six callbacks:
onDestroy(). The system invokes each of these callbacks as an activity enters a new state.
8. How to persist data in an Android app?
There are basically four different ways to store data in an Android app:
- Shared Preferences – to save primitive data in key-value pairs
- Internal Storage – you need to store data to the device filesystem, but you do not want any other app (even the user) to read this data
- External Storage – you might want the user to view the files and data saved by your app
- SQLite database
9. Explain the build process in Android?
First step involves compiling the resources folder (/res) using the aapt (android asset packaging tool) tool. These are compiled to a single class file called R.java. This is a class that just contains constants.
Second step involves the java source code being compiled to .class files by javac, and then the class files are converted to Dalvik bytecode by the “dx” tool, which is included in the sdk ‘tools’. The output is classes.dex.
The final step involves the android apkbuilder which takes all the input and builds the apk (android packaging key) file.
10. What is an Intent in Android?
An Intent is basically a message that is passed between components (such as Activities, Services, Broadcast Receivers, and Content Providers).So, it is almost equivalent to parameters passed to API calls. The fundamental differences between API calls and invoking components via intents are:
- API calls are synchronous while intent-based invocations are asynchronous.
- API calls are compile-time binding while intent-based calls are run-time binding.
To listen for an broadcast intent (like the phone ringing, or an SMS is received), you implement a broadcast receiver, which will be passed the intent. To declare that you can handle another’s app intent like “take picture”, you declare an intent filter in your app’s manifest file.
If you want to fire off an intent to do something, like pop up the dialer, you fire off an intent saying you will.
An Intent provides a facility for performing late runtime binding between the code in different applications.
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