1. What Is Rails?
Rails is a extremely productive web-application framework written in Ruby language by David Hansson.
Rails are an open source Ruby framework for developing database-backend web applications.
Rails include everything needed to create a database-driven web application using the Model-View-Controller (MVC) pattern.
2. Why Ruby On Rails?
There are lot of advantages of using ruby on rails.
DRY Principal( Don’t Repeat Yourself): It is a principle of software development aimed at reducing repetition of code. “Every piece of code must have a single, unambiguous representation within a system”
Convention over Configuration: Most web development framework for .NET or Java force you to write pages of configuration code. If you follow suggested naming conventions, Rails doesn’t need much configuration.
**Gems and Plugins: **RubyGems is a package manager for the Ruby programming language that provides a standard format for distributing ruby programs and library.
Plugins: A Rails plugin is either an extension or a modification of the core framework. It provides a way for developers to share bleeding-edge ideas without hurting the stable code base. We need to decide if our plugin will be potentially shared across different Rails applications.
Scaffolding: Scaffolding is a meta-programming method of building database-backend software application. It is a technique supported by MVC frameworks, in which programmer may write a specification, that describes how the application database may be used. There are two type of scaffolding:
-static: Static scaffolding takes 2 parameter i.e your controller name and model name.
-dynamic: In dynamic scaffolding you have to define controller and model one by one.
Rack Support: Rake is a software task management tool. It allows you to specify tasks and describe dependencies as well as to group tasks in a namespace.
Metaprogramming: Metaprogramming techniques use programs to write programs.
Bundler: Bundler is a new concept introduced in Rails 3, which helps you to manage your gems for application. After specifying gem file, you need to do a bundle install.
3. What Is Orm In Rails?
ORM tends for Object-Relationship-Model, where Classes are mapped to table in the database, and Objects are directly mapped to the rows in the table.
4. What Are The Various Components Of Rail?
Action Pack: Action Pack is a single gem that contains Action Controller, Action View and Action Dispatch. The “VC” part of “MVC”.
Action Controller: Action Controller is the component that manages the controllers in a Rails application. The Action Controller framework processes incoming requests to a Rails application, extracts parameters, and dispatches them to the intended action.
Services provided by Action Controller include session management, template rendering, and redirect management.
Action View: Action View manages the views of your Rails application. It can create both HTML and XML output by default.
Action View manages rendering templates, including nested and partial templates, and includes built-in AJAX support.
Action Dispatch: Action Dispatch handles routing of web requests and dispatches them as you want, either to your application or any other Rack application. Rack applications are a more advanced topic and are covered in a separate guide called Rails on Rack.
Action Mailer: Action Mailer is a framework for building e-mail services. You can use Action Mailer to receive and process incoming email and send simple plain text or complex multipart emails based on flexible templates.
Active Model: Active Model provides a defined interface between the Action Pack gem services and Object Relationship Mapping gems such as Active Record. Active Model allows Rails to utilize other ORM frameworks in place of Active Record if your application needs this.
Active Record: Active Record are like Object Relational Mapping (ORM), where classes are mapped to table, objects are mapped to columns and object attributes are mapped to data in the table.
Active Resource: Active Resource provides a framework for managing the connection between business objects and RESTful web services. It implements a way to map web-based resources to local objects with CRUD semantics.
Active Support: Active Support is an extensive collection of utility classes and standard Ruby library extensions that are used in Rails, both by the core code and by your applications.
5. What Are Helpers And How To Use Helpers In Ror?
Helpers are modules that provide methods which are automatically usable in your view. They provide shortcuts to commonly used display code and a way for you to keep the programming out of your views. The purpose of a helper is to simplify the view.
6. What Is Mvc? And How It Works?
MVC tends for Model-View-Controller, used by many languages like PHP, Perl, Python etc. The flow goes like this:
Request first comes to the controller, controller finds and appropriate view and interacts with model, model interacts with your database and send the response to controller then controller based on the response give the output parameter to view.
7. What Is Request.xhr?
A request.xhr tells the controller that the new Ajax request has come, It always return Boolean values (TRUE or FALSE)
8. How Many Types Of Callbacks Available In Ror?
9. What Is Tdd And Bdd?
TDD stands for Test-Driven-Development and BDD stands for Behavior-Driven-Development.
10. How To Serialize Data With Yaml?
YAML is a straight forward machine parsable data serialization format, designed for human readability and interaction with scripting language such as Perl and Python.
YAML is optimized for data serialization, formatted dumping, configuration files, log files, internet messaging and filtering.
11. What Do You Mean By Naming Convention In Rails.
Variables: Variables are named where all letters are lowercase and words are separated by underscores. E.g: total, order_amount.
Class and Module: Classes and modules uses MixedCase and have no underscores, each word starts with a uppercase letter. Eg: InvoiceItem
Database Table: Table name have all lowercase letters and underscores between words, also all table names to be plural. Eg: invoice_items, orders etc
Model: The model is named using the class naming convention of unbroken MixedCase and always the singular of the table name.
For eg: table name is might be orders, the model name would be Order. Rails will then look for the class definition in a file called order.rb in /app/model directory. If the model class name has multiple capitalized words, the table name is assumed to have underscores between these words.
Controller: controller class names are pluralized, such that Orders Controller would be the controller class for the orders table. Rails will then look for the class definition in a file called orders_controlles.rb in the /app/controller directory.
12. How Many Types Of Relationships Does A Model Has?
13. Get And Post Method?
GET is basically for just getting (retrieving) data, whereas POST may involve anything, like storing or updating data, or ordering a product, or sending E-mail.
14. What Is The Log That Has To Seen To Check For An Error In Ruby Rails?
Rails will report errors from Apache in log/apache.log and errors from the ruby code in log/development.log. If you having a problem, do have a look at what these log are saying.
15. Difference Between Render And Redirect?
render example: render :action, render :partial etc. redirect example: redirect_to :controller => ‘users’, :action => ‘new’
16. What Is Bundler?
Bundler is a new concept introduced in Rails3, which helps to you manage your gems for the application. After specifying gems in your Gemfile, you need to do a bundle install. If the gem is available in the system, bundle will use that else it will pick up.
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Android Interview Questions and Answers from Beginner to Advanced level
DataFlair is committed to provide you all the resources to make you an android professional. We started with android tutorials along with practicals, then we published Real-time android projects along with source code. Now, we come up with frequently asked android interview questions, which will help you in showing expertise in your next interview.
Android – one of the hottest technologies, which is having a bright future. Get ready to crack your next interview with the following android interview questions. These interview questions start with basic and cover deep concepts along with advanced topics.
1. What is Android?
Android is an open-source mobile operating system that is based on the modified versions of Linux kernel. Though it was mainly designed for smartphones, now it is being used for Tablets, Televisions, Smartwatches, and other Android wearables.
2. Who is the inventor of Android Technology?
The inventors of Android Technology are- Andry Rubin, Nick Sears, and Rich Miner.
3. What is the latest version of Android?
The latest version of Android is Android 10.0, known as Android Q. The upcoming major Android release is Android 11, which is the 18th version of Android. [Note: Keep checking the versions, it is as of June 2020.]
4. How many Android versions can you recall right now?
Till now, there are 17 versions of Android, which have their names in alphabetical order. The 18th version of Android is also going to come later this year. The versions of Android are here:
5. Explain the Android Architecture with its components.
This is a popular android developer interview question
Android Architecture consists of 5 components that are-
a. Linux Kernel: It is the foundation of the Android Architecture that resides at the lowest level. It provides the level of abstraction for hardware devices and upper layer components. Linux Kernel also provides various important hardware drivers that act as software interfaces for hardwares like camera, bluetooth, etc.
b. Native Libraries: These are the libraries for Android that are written in C/C++. These libraries are useful to build many core services like ART and HAL. It provides support for core features.
c. Android Runtime: It is an Android Runtime Environment. Android Operating System uses it during the execution of the app. It performs the translation of the application bytecode into the native instructions. The runtime environment of the device then executes these native instructions.
d. Application Framework: Application Framework provides many java classes and interfaces for app development. And it also provides various high-level services. This complete Application framework makes use of Java.
e. Applications: This is the topmost layer of Android Architecture. It provides applications for the end-user, so they can use the android device and compute the tasks.
6. What are the services that the Application framework provides?
The Android application framework has the following key services-
a. Activity Manager: It uses testing and debugging methods.
b. Content provider: It provides the data from application to other layers.
c. Resource Manager: This provides users access to resources.
d. Notification Manager: This gives notification to the users regarding actions taking place in the background.
e. View System: It is the base class for widgets, and it is also responsible for event handling.
7. What are the important features of Linux Kernel?
The important features of the Linux Kernel are as follows:
a. Power Management: Linux Kernel does power management to enhance and improve the battery life of the device.
b. Memory Management: It is useful for the maximum utilization of the available memory of the device.
c. Device Management: It includes managing all the hardware device drivers. It maximizes the utilization of the available resources.
d. Security: It ensures that no application has any such permission that it affects any other application in order to maintain security.
e. Multi-tasking: Multi-tasking provides the users the ease of doing multiple tasks at the same time.
8. What are the building blocks of an Android Application?
This is a popular android interview question for freshers.
The main components of any Android application are- Activity, Services, Content Provider, and Broadcast Receiver. You can understand them as follows:
a. Activity- It is a class that acts as the entry point representing a single screen to the user. It is like a window to show the user interface.
b. Services- Services are the longest-running component that runs in the background.
c. Content Provider- The content provider is an essential component that allows apps to share data between themselves.
d. Broadcast receivers- Broadcast receiver is another most crucial application component. It helps the apps to receive and respond to broadcast messages from the system or some other application.
9. What are the important components of Android Application?
The Components of Android application are listed below:
10. What are the widgets?
Widgets are the variations of Broadcast receivers. They are an important part of home screen customization. They often display some data and also allow users to perform actions on them. Mostly they display the app icon on the screen.
11. Can you name some types of widgets?
Mentioned below are the types of widgets-
a. Informative Widgets: These widgets show some important information. Like, the clock widget or a weather widget.
b. Collective Widgets: They are the collection of some types of elements. For example, a music widget that lets us change, skip, or forward the song.
c. Control Widgets: These widgets help us control the actions within the application through it. Like an email widget that helps check the recent mails.
d. Hybrid Widgets: Hybrid widgets are those that consist of at least two or more types of widgets.
12. What are Intents?
Intents are an important part of Android Applications. They enable communication between components of the same application as well as separate applications. The Intent signals the Android system about a certain event that has occurred.
13. Explain the types of intents briefly?
Intent is of three types that are-
a. Implicit Intents: Implicit intents are those in which there is no description of the component name but only the action.
b. Explicit Intents: In explicit intents, the target component is present by declaring the name of the component.
c. Pending Intents: These are those intents that act as a shield over the Intent objects. It covers the intent objects and grants permission to the external app components to access them.
14. What is a View?
A view is an important building block that helps in designing the user interface of the application. It can be a rectangular box or a circular shape, for example, Text View, Edit Text, Buttons, etc. Views occupy a certain area of the screen, and it is also responsible for event handling. A view is the superclass of all the graphical user interface components.
15. What do you understand by View Group?
It is the subclass of the ViewClass. It gives an invisible container to hold layouts or views. You can understand view groups as special views that are capable of holding other views, that are Child View.
16. What do you understand about Shared Preferences?
It is a simple mechanism for data storage in Android. In this, there is no need to create files, and using APIs, it stores the data in XML files. It stores the data in the pair of key-values. SharedPreferences class lets the user save the values and retrieve them when required. Using SharedPreferences we can save primitive data like- boolean, float, integer, string and long.
17. What is a Notification?
A notification is just like a message that shows up outside the Application UI to provide reminders to the users. They remind the user about a message received, or some other timely information from the app.
18. Give names of Notification types.
There are three types of notifications namely-
a. Toast Notification- This notification is the one that fades away sometime after it pops up.
b. Status Notification- This notification stays till the user takes some action on it.
c. Dialog Notification- This notification is the result of an Active Activity.
19. What are fragments?
A fragment is a part of the complete user interface. These are present in Activity, and an activity can have one or more fragments at the same time. We can reuse a fragment in multiple activities as well.
20. What are the types of fragments?
There are three types of fragments that are: Single Fragment, List Fragment, Fragment Transactions.
21. What are Layout XML files?
Layout XML files contain the structure for the user interface of the application. The XML file also contains various different layouts and views, and they also specify various GUI components that are there in Activity or fragments.
22. What are Resources in Android Application?
The resources in Android Apps defines images, texts, strings, colors, etc. Everything in resources directory is referenced in the source code of the app so that we can use them.
23. Can you develop Android Apps with languages other than Java? If so, name some.
Yes, there are many languages that we can work with, for the development of Android Applications. To name some, I would say Java, Python, C, C++, Kotlin, C#, Corona/LUA.
24. What are the states of the Activity Lifecycle?
Activity lifecycle has the following four stages-
a. Running State: As soon as the activity starts, it is the first state.
b. Paused State: When some other activity starts without closing the previous one, the running activity turns into the Paused state.
c. Resume State: When the activity opens again after being in pause state, it comes into the Resume State.
d. Stopped State: When the user closes the application or stops using it, the activity goes to the Stopped state.
25. What are some methods of Activity?
The methods of Activity are as follows:
26. How can you launch an activity in Android?
We launch an activity using Intents. For this we need to use intent as follows:
27. What is the service lifecycle?
There are two states of a service that are-
a. Started State: This is when the service starts its execution. A Services come in start state only through the startService() method.
b. Bounded State: A service is in the bounded state when it calls the method bindService().
28. What are some methods of Services?
The methods of service are as follows-
29. What are the types of Broadcast?
Broadcasts are of two types that are-
a. Ordered Broadcast: Ordered broadcasts are Synchronous and work in a proper order. It decides the order by using the priority assigned to the broadcasts.
b. Normal Broadcast: These are asynchronous and unordered. They are more efficient as they run unorderly and all at once. But, they lack full utilization of the results.
30. What are useful impotent folders in Android?
The impotent folders in an Android application are-
31. What are the important files for Android Application when working on Android Studio?
This is an important android studio interview question
There are following three files that we need to work on for an application to work-
a. The AndroidManifest.xml file: It has all the information about the application.
b. The MainActivity.java file: It is the app file that actually gets converted to the dalvik executable and runs the application. It is written in java.
c. The Activity_main.xml file: It is the layout file that is available in the res/layout directory. It is another mostly used file while developing the application.
32. Which database do you use for Android Application development?
The database that we use for Android Applications is SQLite. It is because SQLite is lightweight and specially developed for Android Apps. SQLite works the same way as SQL using the same commands.
33. Tell us some features of Android OS.
The best features of Android include-
34. Why did you learn Android development?
Learning Android Studio is a good idea because of the following-
35. What are the different ways of storage supported in Android?
The various storage ways supported in Android are as follows:
36. What are layouts?
Layout is nothing but arrangements of elements on the device screen. These elements can be images, tests, videos, anything. They basically define the structure of the Android user interface to make it user friendly.
37. How many layout types are there?
The type of layouts used in Android Apps are as follows:
38. What is an APK?
An APK stands for Android Package that is a file format of Android Applications. Android OS uses this package for the distribution and installation of the Android Application.
39. What is an Android Manifest file?
The manifest file describes all the essential information about the project application for build tools, Android operating system, and google play. This file is a must for every Android project that we develop, and it is present in the root of the project source set.
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Ruby on Rails is a development tool that offers Web & Mobile App Developers a structure for all the codes they write resulting in time-saving with all the common repetitive tasks during the development stage.
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offers powerful features for the rapid development of deployment-ready applications. It is the most used and best java framework for the development of scalable microservices and web applications.
If you want to become a domain expert, you have come to the right place. We have curated some the most repeatedly asked spring boot interview questions and answers to help you ace the interview.
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Rails is a server-side web application development framework written in the Ruby programming language. Its emergence in 2005 has influenced and impacted web application development to a vast range, including but not limited to seamless database tables, migrations, and scaffolding of views. In the simplest understanding, Rails is a highly productive and intuitive software developer.
Websites and applications of any complexity can be achieved with Ruby on Rails. The software is designed to perceive the needs of ruby on rails developers and encourage them with the best way out. It is designed to allow developers to write lesser code while spiking productivity much more than any other framework or language. Ruby on Rails rapid application development offers everyday web development tasks easier and uniquely out-of-the-box, both with the same effectiveness.
The Ruby on Rails framework is based on two philosophies:
Some of the commonly known websites built by the Ruby on Rails software developers are Instacart, Scribd, Shopify, Github, ConvertKit, Soundcloud, GoodReads, Airbnb. It finds its application in Sa-as Solutions, Social Networking Platforms, Dating websites, Stock Exchange Platforms, etc.
There is a large community that is dedicated to Ruby on Rails that keeps it up-to-date and indeed encourages its family of developers to continue using it. They make sure the benefits are soaring with every update they make.
The community is committed to developing several ready-to-use code packages, commonly known as gems, for its users. They discuss and announce new project launches, help each other with queries, and engage in framework discussions and betterment. While Ruby on Rails helps developers in rapid application development, it also connects and grows businesses together.
To talk about scalability, we indicate the ability to grow and manage more and more user requests per minute (RPM). However, this depends on the architecture rather than the framework. The right architecture of Ruby on Rails web application development allows it to write bulky codes and programs as compared to early-stage difficulties with scalability.
It uses the Representational State Transfer (REST) architecture. This will enable Rails to create efficient web applications based on Rails 6, launched last year in 2020, which addresses most scalability issues. The portable components are agile and help in a better understanding of new requirements and needful adaptations for any business. The framework and architecture allow both vertical and horizontal scalability.
Fast Application Development and Cost Effectiveness
Ruby on Rails is lucid, logical, and has lean code requirements, thereby cutting down redundancy and improving the overall development speed. Lesser amount of code is proportional to lesser time investment with optimal results. The more time it takes for development, the more expensive it becomes for the end customers.
Considering the ready-made code modules/packages (gems) available, Ruby on Rails development company will less time and money are spent creating and modifying Rails websites and applications. Another advantage that has made Ruby on Rails super attractive for startups is its use of Model-View-Controller (MVC) architecture. It has a component separation scheme that speeds up the web development process and fixes any errors that occur.
Rails framework and the Ruby on Rails community put in a lot of efforts for data protection and security of its customer base. It is also one of the efficient frameworks for developing database-backed applications.
The developers at Ruby on Rails cover many aspects of cybersecurity, including encryptions of passwords, credit card information, and users’ personal database. Special measures are taken to prevent the framework from SQL injections and XSS attacks.
Ruby on Rails simplifies the daily operations and lowers the cost of enterprise app developments. The prominent features include data management, seamless updating of applications, easy and efficient code development, and high scalability, as discussed above.
Ruby on Rails enterprise application development is preferred by companies and is slightly cost-intensive. It can be easily integrated with third-party apps like Oracle Business, Oracle, Windows services, and others. Ruby enterprise app development allows the developers and programmers to solve the problems at the root level, given its transparency.
Checkout Blog on Django vs Ruby on Rails Comparison
There are several reasons to prefer Ruby on Rails discussed above and extend further to early detection of errors, reduced time to market, and easy adaptation for API developments. It makes web programming much easier and simplifies website building of any complexity. Its flexibility and acceptance among new developers and programmers make it the perfect, one-stop choice for software application development company in 2021.
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