What is MVC, MVP and MVVM in details

The user interface often contains a lot of cluttered code primarily because of the complicated logic it needs to handle. The presentation patterns are design primarily with one objective in mind, reducing the complex code in the presentation layer and making the code in the user interface clean and manageable.

In this post, I will present a discussion on the MVC, MVP, and MVVM design patterns and highlight when one should be the design of choice over the other.

Model View Controller

The Model View Controller (commonly known as MVC) framework helps you to build applications that are easier to test and maintain. It comprises of three major components, namely:

  1. Model -- this is the layer that represents the application's data
  2. View -- this represents the presentation or the user interface layer
  3. Controller -- this layer typically contains the business logic of your application
The primary objective of the MVC design pattern is separation of concerns to facilitate testability. The Model View Controller design pattern enables you to isolate the concerns and makes your application's code easier to test and maintain. In a typical MVC design, the request first arrives at the controller which binds the model with the corresponding view. In the MVC design pattern, the view and the controller makes use of strategy design and the view and the model are synchronized using the observer design. Hence, we may say that MVC is a compound pattern. The controller and the view are loosely coupled and one controller can be used by multiple views. The view subscribes to the changes in the model.

Model View Presenter

The MVP (Model View Presenter) design pattern also comprises of three components - the model, the view and the presenter. In the MVP design pattern, the Controller (in MVC) is replaced by the Presenter.

You can see : Android MVP Pattern Example

Unlike the MVC design pattern, the Presenter refers back to the view due to which mocking of the view is easier and unit testing of applications that leverage the MVP design pattern over the MVC design pattern are much easier. In the MVP design pattern, the presenter manipulates the model and also updates the view. There are two variations of this design. These include the following.

  1. Passive View -- in this strategy, the view is not aware of the model and the presenter updates the view to reflect the changes in the model.
  2. Supervising Controller -- in this strategy, the view interacts with the model directly to bind data to the data controls without the intervention of the presenter. The presenter is responsible for updating the model. It manipulates the view only if needed -- if you need a complex user interface logic to be executed.
While both these variants promote testability of the presentation logic, the passive view variant is preferred over the other variant (supervising controller) as far as testability is concerned primarily because you have all the view updated logic inside the presenter.

The MVP design pattern is preferred over MVC when your application needs to provide support for multiple user interface technologies. It is also preferred if you have complex user interface with a lot of user interaction. If you would like to have automated unit test on the user interface of your application, the MVP design pattern is well suited and preferred over the traditional MVC design.

Model - View - ViewModel (MVVM)

The Model - View - ViewModel (MVVM) is a variation of Martin Fowler's Presentation Model design pattern. The MVVM is a refinement of the popular MVC design and the ViewModel in MVVM is used to facilitation Presentation Separation. In the MVVM the logic is stored in the presenter and the view is completely isolated from the model.

See this : Top 10 Programming Architectural Patterns

While the presenter isn't aware of the view, the view is aware of the presenter -- the presenter in MVVM is used to represent an abstract view of the user interface. A passive view implies that the view doesn't have any knowledge of the model. In the MVVM design pattern, the View is active and contains behaviors, events and data binding information. Note that the view in MVVM is not responsible for managing the state information -- the view is rather synchronized with the viewmodel. The viewmodel in MVVM is responsible for presentation separation and exposes methods and commands to manage the state of a view and manipulate the model.

How does the view and the viewmodel in MVVM communicate? 

Well, the view and the viewmodel in MVVM communicates using methods, properties and events. The bi-directional databinding or the two way databinding between the view and the viewmodel ensures that the models and properties in the viewmodel is in sync with the view. The MVVM design pattern is well suited in applications that need support for bi-directional databinding.

Google Play Protect – A New Way To Protect Your Phone

Thanks to the increasing number of security holes and increased number of cyber attacks, protecting your phone is more important than ever before.

Google knows this so they’ve begun rolling out Google Play Protect which was originally announced at I/O 2017.

Essentially a part of the company’s existing security services, Google Play Protect begins rolling out today to Google Mobile Services 11 and up. You can find out which version of Google Mobile Services your device is running by heading to Settings > Google > Security > Verify Apps.

You can read some comparison with Google Oreo :

Compared to the existing security services,Play Protect is more visible and better highlights the security it’s providing.

Google says it will automatically scan apps from the Play Store that are installed on your phone to ensure they’re safe; any apps that don’t measure up will either be blocked or removed from your device.

Play Protect is still rolling out to the Google Play Store and will appear in the Updates section.  Apps will soon also include a “Verified by Google Play Protect” badge to help reassure you.

The security system that never sleeps

Google Play Protect continuously works to keep your device, data and apps safe. It actively scans your device and is constantly improving to make sure that you have the latest in mobile security. Your device is automatically scanned around the clock to give you peace of mind.

One less worry for over a billion users

Backed by the strength of Google, Play Protect brings control to your fingertips while giving guidance along the way. Together, we lay out the ideal security blanket for your mobile device. Consider yourself covered.

Control within reach, even if your device isn’t

If you’ve misplaced your device, just take a breath. Find My Device has you covered. You can locate your device by signing into your Google account, or even call it directly from your browser. Lock your phone remotely or display a message on the lock screen, so that if someone finds it they know whom to contact. If you’re convinced it’s lost for good, you can erase all your data. Crisis averted.

Some Kotlin Problem with solutions Every developer need to know

Kotlin is all the rage lately. And while I do agree that the language is well thought out, it does have — as with everything else — its flaws.

As we already discuss about disadvantage of Kotlin but today in this article I’ll explain some of the Kotlin problems I encountered and try to help you avoid them.
You have to see : Advantage and why you should switch to Kotlin

Top 9 Kotlin problems with their solution:

The mystery null

Image result for null

In Kotlin you can write your code as if null never existed and this can make you forget that null is omnipresent but it hides. Let’s look at this simple and seemingly innocent class:
  1. class Foo {
  2. private val c: String
  3. init {
  4. bar()
  5. c = ""
  6. }
  7. private fun bar() {
  8. println(c.length)
  9. }
  10. }
If you try to instantiate this, you’ll get a NullPointerException because bartried to access the length of c before it was initialized.
Of course the application logic was flawed here, but you still got an Exception. The worst part of this is that your IDE won’t complain about this.
The takeaway here is that Kotlin will help you in a lot of cases (nearly all) to avoid null, but you can’t forget about it and from time to time you’ll encounter things like this.
For every Kotlin developer : Top 20 Daily used Kotlin Code Snippet

Handling nulls from the JDK

Image result for Handling nulls

Kotlin’s standard library handles nulls fine. But if you use classes from the JDK, you will have to handle possible null pointers from library functions by hand.
Most of the time the Kotlin classes are enough, but sometimes you have to use something like the ConcurrentHashMap:
  1. val map = ConcurrentHashMap<String, String>()
  2. map["foo"] = "bar"
  3. val bar: String = map["foo"]!!
In this case, you have to use the !! operator. But in other cases the nullsafety operator (?) can also work. Nevertheless, if you use Java libraries extensively you’ll have to litter your code with !!s and ?s or write adapters for Java classes. This is something you can’t really avoid.
There’s another more hideous problem you might bump into. When using methods on JDK classes, they can return null and don’t have syntactic sugar like the Map access above.
Source: Kotlin Problems and How to avoid them? 

Best Android Animation Library in 2017

These are my 10 favorite new Android animation libraries that have come out since October 2017. Some of them aren’t production ready yet, but you may have lots of fun using them. I hope you enjoy these.

Here they are in no particular order:

1. Make Soup animation

Pull-to-refresh is a great place for creativity! But Yalantis building cool pull-to-refresh called Pull To Make Soup animation not only for the purpose of self-expression. These small components can actually help app publishers make their applications stand out.

2. SpaceTabLayout Animation

SpaceTabLayout animation which is a awesome TabLayout for Android with a central Floating Action Button.
This is a custom implementation of a RelativeLayout that you can use along with a ViewPager to navigate between fragments.

3. HollyViewPager Navigation Animation

Android Navigation animation is a master key of any Android application and previously we see the article about animation sidebarTwo panel layout animationbubble tab animation and many more.Consistent navigation is an essential component of the overall user experience. Few things frustrate users more than basic navigation that behaves in inconsistent and unexpected ways.

4. FancyTrendView UI Animation

I take assume that you’re aware from Google trends which is a public web facility of Google Inc., based on Google Search, that shows how often a particular search-term is entered relative to the total search-volume across various regions of the world, and in various languages.

5. Wave Sidebar Animation

Previously we discuss how to implement basic animating sidebar in Android and now we increase our level with adding Wave Sidebar Animation in Android application.

6. Progress Button Animation

Most of time we need to keep busy the user when they perform button click and working in background process in Android. So we use Progress bar or dialog but here you can use progress button Android library which is an Android Button that morphs into a loading progress bar.

7. Swipe3DRotateView Animation

Swipe3DRotateView is a class designed to simplify the implementation of 3D Flip Rotation in android based on swipe gestures.
It is extended from a Framelayout and should exactly contain 2 views as its children. It detects swipe gestures on its child view, and based on the swipe direction, rotates the children in a 3D manner on their X or Y axis.

8. Android AdaptiveTableLayout CSV Animation

CleverRoad introduce their new library named AdaptiveTableLayout which makes it possible to read, edit and write CSV files. If you use Android-based device, you can easily use this library for implementation of all mentioned actions.
As a result, you will be able to change rows and columns, display the picture via link, and align the required data. It will surely help you cope with your tasks faster and make your output higher. AdaptiveTableLayout Android library is seems like your disposal.

9. Two Panels Layout Animation

Two Panels Layout Animation Android Library is fully customizable with a drag-gable divider where you can hide and show the fragments in vertical and horizontal and customize the behavior on orientation changes. The library have a slider separating the fragments, you can drag this slider and the fragments resize the views inside.

10. Android PagerSlidingTabStrip Animation

Recently we discuss about Bubble Tab Animation int tab but you love Materialize tab then you can add Android PagerSlidingTabStrip. It is an interactive indicator to navigate between the different pages of a ViewPager.
Interactive paging indicator widget, compatible with the ViewPager from the Android Support Library.
That’s it. I hope you enjoyed the article! If I didn’t mention any other great libraries released in Animation, please let me know in the comments below. Let’s keep that list bigger together!