Basics

Question 1

What is the android architecture component

Answer 1

A collection of libraries that help you design robust, testable and maintainable apps

Question 2

Difference between activity and fragment

Answer 2

Activity is a single, focused thing that the user can do. Fragment is a modular piece of an activity than can be reused

Question 3

What is a service

Answer 3

A component that runs in the background to perform long-running operations

Question 4

What is an intent

Answer 4

A message object used to request an action from another component

Question 5

Explain the android lifecycle

Answer 5

The series of states an activity goes through from creation to destruction.

Question 6

List all lifecycle states

Answer 6

onCreate()
onStart() <— onRestart() ——-v
onResume()
Activity Running
onPause()
onStop() —> onRestart () ——-^
onDestroy()

Question 7

What’s the difference of AsyncTask and Loader

Answer 7

AsynkTask for short background tasks like downloading a small image.
Loader for loading data from a content provider like fetching contacts

Question 8

What is Content Provider

Answer 8

A component that manages a shared set of data, like contacts, or calendar events

Question 9

What is the difference between SharedPreferences and SQLite

Answer 9

SharedPreferences is for storing simple key-value data like user settings.
SQLite is for storing structured data, like a database of contacts

Question 10

Explain the role of the AndoidManifest.xml file

Answer 10

Declares components, permissions, and other information about the app

Question 11

What’s the difference between a hard and a soft reference

Answer 11

A hard reference prevents an object from being garbage collected, while a soft reference allowed it to be collected under memory pressure

Question 12

What is an activity

Answer 12

Is a single screen in an android app that represents the user interface

Question 13

What is a fragment

Answer 13

A modular piece of an activity that can be reused in different layouts

Question 14

What is AsyncTask

Answer 14

A class that performs background operations and publishes results on the UI thread

Question 15

What is a Loader

Answer 15

A component that asynchronously loads Data from a content provider in the background and delivers it to the UI
(Deprecated, use viewmodel and live data)

Question 16

What is SharedPreferences

Answer 16

A simple way to store key-value pairs of data, like user preferences

Question 17

What’s is SQLite

Answer 17

A lightweight database for storing structured data like contacts

Question 18

What’s is a hard reference

Answer 18

A direct reference to an object that prevents it from being garbage collected

Question 19

What is a soft reference

Answer 19

A reference to an object that allows it to be garbage collected under memory pressure

Question 20

What is a soft reference

Answer 20

A weak reference to an object that allows it to be garbage collected under memory pressure

Question 21

What is a Broadcast receiver

Answer 21

A component that responds to system-wide broadcast announcements

Question 22

What is a notification

Answer 22

A message displayed to the user outside the app’s UI

Question 23

Explain the concept of intents and intent filters

Answer 23

Intents are message objects that request an action from a component
Intent filters allow the system to find a suitable component

Question 24

What’s the difference between implicit and explicit intents

Answer 24

Explicit intents specify the target component, while implicit intents allow the system to find a suitable component

Question 25

What is the purpose of that Android SDK

Answer 25

A set of development tools and APIs provided by Google for building Android apps

Question 26

What is the Android Debug Bridge (ADB)

Answer 26

A command-line tool for communicating with a connected Android device

Question 27

What's the difference between emulators and simulators

Answer 27

Emulators simulate the entire hardware and software, while simulators only simulate the software

Question 28

What is the role of the R file in an Android Project

Answer 28

Contains resource identifiers generated by the android build system

Question 29

What is the difference between a layout and a view

Answer 29

Layout contains views, while a view is a UI element displayed on the screen

Question 30

What are the different types of layouts in Android

Answer 30

Linear layout, relative layout, constraint layout, frame layout, android table layout

Question 31

What is the purpose of the Android Resource Manager

Answer 31

Manages non-code resources like images, strings, and layouts

Question 32

Explain the concept of density-independent pixels (DP)

Answer 32

A unit of measurement for UI elements that adapts to different screen densities

Question 33

What is the android asset Pipeline

Answer 33

Compiles and packages app resources for different device configurations

Question 34

What is the difference between a drawable and a mipmap

Answer 34

Drawables are general-purpose images, while mipmaps are optimized for different screen densities

Question 35

What is the purpose of the build.gradle file

Answer 35

Configures the build process for an Android project

Question 36

What is the android Gradle plugin

Answer 36

A plugin that extends the Gradle build system for Android projects

Question 37

What is dependency injection

Answer 37

A software design pattern for providing dependencies to components

Question 38

What is the purpose of Dagger

Answer 38

A dependency injection framework for Android

Question 39

What is a RecyclerView

Answer 39

A flexible view for displaying large lists of data efficiently

Question 40

What is a CardView

Answer 40

A layout for displaying information inside a card with a shadow

Question 41

What is a ViewPager

Answer 41

A container for dynamically adding and removing views

Question 42

What is a TabLayout

Answer 42

A component for displaying tabs to switch between different views in a ViewPager

Question 43

What is a CoordinatorLayout

Answer 43

A flexible layout that allows you to create complex layouts with fewer nested views

Question 44

What is a Navigation Drawer

Answer 44

A side drawer that displays navigation options

Question 45

What is a Bottom Navigation Bar

Answer 45

A Navigation bar at the bottom of the screen for switching between top-level destinations

Question 46

What is a Progress Bar

Answer 46

A visual indicator of progress

Question 47

What is a ProgressDialog

Answer 47

A dialog that displays progress information

Question 48

What is the difference between a ProgressDialog and a Progress Bar

Answer 48

A ProgressDialog is a dialog-style progress indicator, while a Progress Bar is a view that can be embedded in other layouts

Question 49

What is a Toast

Answer 49

A short message displayed at the bottom of the screen

Question 50

What is a Snackbar

Answer 50

A message displayed at the bottom of the screen with an optional action

Question 51

What is the lifecycle of a Fragment

Answer 51

Similar to an Activity, but with additional states onAttach(), onCreate(), onCreateView(), onViewCreated(), onStart(), onResume(), onPause(), onStop(), onSaveInstanceState(), onDestroyView(), onDestroy(), onDetach()

Question 52

What is the difference between a back stack and a fragment back stack

Answer 52

Back stack manages the history of activities, while a fragment back stack manages the history of fragments within an Activity

Question 53

What is the purpose of the View model class

Answer 53

In MVVM, It separates the UI from the business logic, while also storing data used by activities or fragments so it survives configuration changes

Question 54

What is the purpose of the LiveData class

Answer 54

Observable data holder that updates UI automatically when data changes

Question 55

What is the purpose of the Room persistence library

Answer 55

An abstraction layer over SQLite for accessing database data

Question 56

What is the purpose of Retrofit

Answer 56

A type-safe HTTP client for making network requests