How to get different way of alphabetical letter in Kotlin

Using collection in kotlin is very easy to loop over the list. Here I am presenting way of getting alphabetically letter from A to Z in different way in kotlin.

Following output above code:
Print A to Z
ABCDEFGHIJKLMNOPQRSTUVWXYZ
-------------------------
ABCDEFGHIJKLMNOPQRSTUVWXYZ
Print A to Z using With
-------------------------
Print A to Z using expression
ABCDEFGHIJKLMNOPQRSTUVWXYZ
-------------------------
print A to Z using apply
ABCDEFGHIJKLMNOPQRSTUVWXYZ
-------------------------
Print using buildString
ABCDEFGHIJKLMNOPQRSTUVWXYZ

 Happy Coding

#HappyCoding #ILoveKotlin #Android #KotlinLang #AndroidStudio

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First android app developed using Kotlin

I just started learning kotlin since google I/O air in 2017. I brought two books Kotlin in Action by Dmitry Jemerov and Svetlana Isakova and Kotlin for Android Developers by Antonio Leiva.


I developed small application "Tic Tac Toe" both 3x3 and 4x4 , which is published on google play store.


Here is the sample snapshots of Tic Tac Toe from google play store. Please checkout and expecting good suggestion.How do i improved the existing app.

Google Play: Download


#HappyCoding #IloveKotlin

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Override Equal, HashCode and ToString in Kotlin

We all know that override equal(), hashcode() and toString() in java, Here in Kotlin by default implementation, you don't have to need override them. However, if you want to override toString, equals and hashCode, you have to do this.

equals: 

open operator fun equals(other: Any?): Boolean

Indicates whether some other object is "equal to" this one. Implementations must fulfil the following requirements:

• Reflexive: for any non-null reference value x, x.equals(x) should return true.
• Symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• Transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true
• Consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.

Note that the == operator in Kotlin code is translated into a call to equals when objects on both sides of the operator are not null.

hashCode:

open fun hashCode(): Int

Returns a hash code value for the object. The general contract of hashCode is:

• - Whenever it is invoked on the same object more than once, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified.
• - If two objects are equal according to the equals() method, then calling the hashCode method on each of the two objects must produce the same integer result.

toString:

open fun toString(): String

Returns a string representation of the object.

------------------------------------------------------------

Here is the full implementation kotlin code:

Output looks like

without override equals , hashCode and toString method

false

false

euquals
false

false

toString
co.prandroid.firstkotlin.MainActivity$User@4c83bb6
hashCode
80231350

with override equals , hashCode and toString method

false

true

euquals
false

true

toString
Client(name=john, code=12345)

hashCode
101315726

Reference: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html

#HappyCoding #ILoveKotlin

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How to use RecyclerView in Android using Kotlin

Yes, we all love develop mobile application, but some case there is lots boilerplate, null safety problems in java, which is more concise using kotlin.

RecyclerView is a flexible view for providing a limited window into a large data set.It is a modernized version of the ListView and the GridView classes provided by the Android framework. Recycler view addresses several issues that the existing widgets have.

I assume, you have already download latest Android Studio 3.0 preview, If you have not download , please follow the download an install Android Studio 3.0 Preview, which includes Kotlin support out of the box.

RecyclerView allow to use different layout managers for positioning items. Such as LinearLayout, GridLayout and StaggerLayout. I have developing  all there layout and populate data on all the layouts.

Glide used for Image display.

1. First you have to add dependencies on app gradle, following dependencies.

implementation 'com.android.support:recyclerview-v7:25.4.0'
compile 'com.github.bumptech.glide:glide:3.5.2'

2. We must have to make add recyclerview on layout file .


3. Now we have to declear Pojo class in kotlin, which is more easy and simple


4. Create simple data using through object in kotlin.


5. Now, we have make MovieAdapter in Kotlin is simple, which is more complex in java.


6. Declear Recycler view and set layout depend you requirement, like Linear, Grid and Stagger.

7. If you want to make divider in your recycler view , then you using RecyclerView.ItemDecoration.
8. Finally, Application ready to run, and then we have get following snapshots.

To get full source code, please download and fork github repository. Download

#HappyCoding #ILoveKotlin

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Simple use of glide library for display images on android

We know all that memory to store images on mobile is limited, if we have display images using through the bitmap images, it will take lots of memory, which is followed by ultimately memory performance and finally application will be slow.

Yes, we have new image display library call glide. Glide is the perfect and best one to use compared to Picasso and Fresco.

Reasons of using Glide:

1. Recommended by Google and has been used in many Google open source projects.
2. Picasso loads the full-size image (1920x1080 pixels) into the memory and let GPU does the real-time resizing when drawn. While Glide loads the exact ImageView-size (768x432 pixels) into the memory which is a best practice.
3. Glide cache both the full-size image and the resized one. Picasso will cache only single size of image, the full-size one. Glide acts differently, caches separate file for each size of ImageView.
4. GIF (animated image) support.
5. In addition, it also helps preventing an app from popular OutOfMemoryError.

Fresco has huge size of library and cache also. Moreover, app freezes while loading big images from internet into ListView.

While Glide has small size of both library and cache.(Source: Quora)

Here is the pictorial difference between Glide vs Picasso vs Fresco.

Now, How to use Glide to display images on Android, Here is the simple steps,

First you have to introduces dependencies on gradle.

compile 'com.github.bumptech.glide:glide:3.5.2'

and 

On your imageview, please provide this code for display images.

image is image view , depend you requirement, 

In kotlin:

val image = currentView.findViewById(R.id.image) as ImageView

In Java

ImageView image= (ImageView) findViewById(R.id.image)

Now, render the image url on our imageview.

Glide.with(context)

.load(currentVolume.imageUrl)

.into(image)

#HappyCoding #ILoveKotlin

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Hello World and Button Click Event fire in Kotlin (Android) .

We are going to series of kotlin tutorials for android. JetBrains software company introduce new android studio 3.0 in build kotlin plugin, we don't have to add any plugin.
First you have to download Android Studio 3.0 Canary 4 is now available on developer.android.com and learn kotlin from the basic , there is a official documentation of kotlin.
https://kotlinlang.org/.

Let start kotlin

We are going to print simply hello world, then we will moving series of kotlin for android developer.

After finish download android studio, then follow the follow the following steps.


1. Open Android studio 3.0

2. Click File -> New -> New Project.

3. The give the name of Project and you have see by default kotlin plugin checked on android studio.Then click Next.

4. Then choose target Minimum SDK for the application.

5.  Now choose the Activity to mobile, by default there is empty activity, choose this and click next.

6. Finally, when you click finish, then it take few seconds for loading gradles, libraries and other necessary files for mobile application.

Now, your project is created, initially, you can see different then tradition java code because it is kotlin. you simple run the project you have to see, hello world.

I am going to simple change the App, We give the input from EditText and click show Button and display on TextView.

Let start to do this,

Here is the simple layout file:



Here is the simple kotlin code, which is more less and more clear to understand then java code.




Here is the simple output of above program:

I love kotlin and please follow the next tutorials.

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Kotlin For Android Apps

Kotlin is an Android-compatible language that is concise, expressive, and designed to be type- and null-safe. It works with the Java language seamlessly, so it makes it easy for developers who love the Java language to keep using it but also incrementally add Kotlin code and leverage Kotlin libraries. Also, many Android developers have already found that Kotlin makes development faster and more fun, so we want to better support these Kotlin users.

Kotlin is a great fit for developing Android applications, bringing all of the advantages of a modern language to the Android platform without introducing any new restrictions:

• Compatibility: Kotlin is fully compatible with JDK 6, ensuring that Kotlin applications can run on older Android devices with no issues. The Kotlin tooling is fully supported in Android Studio and compatible with the Android build system.
• Performance: A Kotlin application runs as fast as an equivalent Java one, thanks to very similar bytecode structure. With Kotlin's support for inline functions, code using lambdas often runs even faster than the same code written in Java.
• Interoperability: Kotlin is 100% interoperable with Java, allowing to use all existing Android libraries in a Kotlin application. This includes annotation processing, so databinding and Dagger work too.
• Footprint: Kotlin has a very compact runtime library, which can be further reduced through the use of ProGuard. In a real application, the Kotlin runtime adds only a few hundred methods and less than 100K to the size of the .apk file.
• Compilation Time: Kotlin supports efficient incremental compilation, so while there's some additional overhead for clean builds, incremental builds are usually as fast or faster than with Java.
• Learning Curve: For a Java developer, getting started with Kotlin is very easy. The automated Java to Kotlin converter included in the Kotlin plugin helps with the first steps. Kotlin Koans offer a guide through the key features of the language with a series of interactive exercises. 

If want to learn kotlin, today now, please follow the following links

• Download an install Android Studio 3.0 Preview, which includes Kotlin support out of the box.
• Follow the Getting Started with Android and Kotlin tutorial to create your first Kotlin application.
• For a more in-depth introduction, check out the reference documentation on this site and Kotlin Koans.
• Another great resource is Kotlin for Android Developers, a book that guides you step by step through the process of creating a real Android application in Kotlin.
• Check out Google's sample projects written in Kotlin. Source content(KotlinLang)

I am going to write some kotlin tutorials for android and java, based on official website, and other books like kotlin in Action, kotlin for android developer. please follow thing updated my tutorials.

#HaveANiceKotlin #HappyCoding

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Introducing Kotlin in Google I/O 2017

Google introducing kotlin new programming language in Google I/O 2017 and Kotlin is now an officially supported language for Android. Simply Kotlin is a statically-typed programming language that runs on the Java Virtual Machine and also can be compiled to JavaScript source code or uses the LLVM compiler infrastructure[from wiki].

Here are some vidoe, that are presented on Google I/O 2017.

Getting Started with Kotlin

Introduction to Kotlin (Google I/O '17) 

  Life is Great and Everything Will Be Ok, Kotlin is Here (Google I/O '17) 

Would you learn more about kotlin, please visit:

All vedio source by official google Android Developers channels.

Happy Coding

#Kotlin #AndroidDeveloper #IO17 #GoogleIO17

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How to get Android O sdk in Android Studio

Android O introduces several new features and APIs, and includes changes that can affect the behavior of your app even if you change nothing.

1. Install Android Studio 2.4 Canary. Only Android Studio 2.4 includes support for all the new developer features available with Android O. So you need to get the canary version of Android Studio 2.4 to begin using the Android O SDK. But you can still keep your stable version of Android Studio installed.
   
2. Launch Android Studio 2.4 and open the SDK Manager by clicking Tools > Android > SDK Manager.
3. In the SDK Platforms tab, check Show Package Details. Below Android O Preview check the following:
   • Android SDK Platform O
   • Google APIs Intel x86 Atom System Image (only required for the emulator)
4. Switch to the SDK Tools tab and check all items that have updates available (click each checkbox that shows a dash ). This should include the following that are required:
   • Android SDK Build-Tools 26.0.0 (rc1 or higher)
   • Android SDK Platform-Tools 26.0.0 (rc1 or higher)
   • Android Emulator 26.0.0
   • Support Repository
5. Click OK to install all the selected SDK packages.

Now you're ready to starting developing with the Android O Developer Preview.

Update your build configuration

Update compileSdkVersion, buildToolsVersion, targetSdkVersion, and the Support Library version with the following versions:

android {
  compileSdkVersion 'android-O'
  buildToolsVersion '26.0.0-rc1'

  defaultConfig {
    targetSdkVersion 'O'
  }
  ...
}

dependencies {
  compile 'com.android.support:appcompat-v7:26.0.0-alpha1'
}

You cannot publish your app with this configuration. The "O" version is a provisional API level that is usable only for development and testing during the Android O Developer Preview. You must wait to publish your Android O changes until the final API level is released, and then update your configuration again at that time.

More about Android O: https://developer.android.com/index.html

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Interview Question: find the angle between hour hand and minute hand

Recently, I gave interview on the reputed company in silicon valley, I figure out the solution to that problem with solution in android.

Question: 
How do you find the angle between hour hand and minute hand with two input field, one is an hour and next one is minute and click the button find the angle, and calculate the angle between two input in textview.
Time: 30 Minute

Solution:
They given me, Hour: 6  and Minute: 30 and output will be 15

I took the base case for hour 12:00 (h = 12, m = 0) as a reference and followed these steps.

• Calculate the angle made by hour hand with respect to 12:00 in h hours and m minutes.
• Calculate the angle made by minute hand with respect to 12:00 in h hours and m minutes.
• The difference between two angles is the angle between two hands.

And I told them if I move minute hand  360 degree in 60 minute(or 6 degree in one minute) and move hour hand  360 degree in 12 hours(or 0.5 degree in 1 minute). 

In hour hours and minute minutes, 

#  minute hand would move to the (hour*60 + minute)*6 and 

# hour hand would move to the(h*60 + m)*0.5.

if you get the confuse above equation, please put the real hour and minute value check, it would be correct.

Now, I started to coding in android

Step 1: Layout

The layout is very easy, in relative layout, you can just put textview for label and editext for input for both hour and minute and the button for click and gives output, finally, I put one textview for display out.

Here is the Layout code, if you have any confusion:

Now, I am going to write, the actual code that I have present during interview session:

Here is the Acutal output of snapshot:

I am still waiting for response!!
Happy Coding !!!

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How to use Retrofit to get data from stackoverflow API and GitHub Demo in android studio

Retrofit is a type-safe REST client for Android developed by Square. The library provides a powerful framework for authenticating and interacting with APIs and sending network requests with OkHttp. See this guide to understand how OkHttp works.

This library makes downloading JSON or XML data from a web API fairly straightforward. Once the data is downloaded then it is parsed into a Plain Old Java Object (POJO) which must be defined for each "resource" in the response.

Setup

Must be defined on internet permission on AndroidManifest.xml .

Dependencies

Add following dependencies on app/build.gradle file:

Converter:

Here is the different type of  Gson converter, we can use them:

How to create retrofit instance, 

then we have to define, the userendpoint:

Now, create model class, user variables, In MainActivity.java, we have to create instance of APIClient and call the users.

Download Full code: https://github.com/dharmakshetri/Android-API-Demos

and you can find out Awesome Retrofit Article: Retrofit Tutorial With Example In Android Studio [Step by Step]

More details:

https://square.github.io/retrofit/
https://github.com/square/retrofit
https://guides.codepath.com/android/Consuming-APIs-with-Retrofit
https://realm.io/news/droidcon-jake-wharton-simple-http-retrofit-2/
http://www.vogella.com/tutorials/Retrofit/article.html


Happy Coding !!!

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What’s new – Material design (December 2016)

In the Material design in August 2016, three Notifications, Widgets and Confirmation and acknowledgement.

source:matrial.io

Now in December 2016, In Material design here is the latest added new section and significance updates.

New sections

• Platforms discusses when and how to adapt apps to Material Design, and when to adhere to platform conventions
• App shortcut icons contains specs on how to create app shortcut icons for the home screen
• Help and feedback describes how to indicate, craft, and place help content

Significant updates

• Bidirectionality has updated guidance on mirroring UI content and icons in right-to-left (RTL) languages
• Accessibility contains new guidance on sound, controls, labeling elements, and testing
• Selection includes detailed examples on item selection, toggling, and styling

Happy Coding !!!

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Firebase: Save, Delete and Retrieve data from firebase database in Android Studio

In Firebase Realtime Database we can store and sync data with our NoSQL cloud database. Data is synced across all clients in realtime, and remains available when your app goes offline.

The Firebase Realtime Database is a cloud-hosted database. Data is stored as JSON and synchronized in realtime to every connected client. When you build cross-platform apps with our iOS, Android, and JavaScript SDKs, all of your clients share one Realtime Database instance and automatically receive updates with the newest data.

Android Setup

Here is the one example how to store on firebase and retrieve data on your android device.

First step Create firebase project  from https://console.firebase.google.com.

Add the dependency for Firebase Realtime Database to your app-level build.gradle file:



Update the rules for your database to allow reads and writes from all users, as this demo will not cover Firebase Authentication.


Steps:
1. Create firebase database reference
2. Get data from your form
3. Add and push data on database
4. Update on your view using creating anonymous inner class ChildEventListener.
5. Check you firebase database

Here is the full code:





Update on recyclerview, which show in below git hub link.

Output Snapshots:

Clone the github java
$git clone https://github.com/dharmakshetri/FirebaseAddOrDeleteonDatabase.git

Happy Coding !!!

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RxAndroid Example to display data on RecyclerView in Android Studio

RxAndroid is simple in one term is reactive extension for android.
Android authorities defined, Observables and Observers in terms of RxAndrod, There are two basic and very important items in reactive programming, Observables and Observers. Observables publish values, while Observers subscribe to Observables, watching them and reacting when an Observable publishes a value.

In simpler terms:

    An Observable performs some action, and publishes the result.
    An Observer waits and watches the Observable, and reacts whenever the Observable publishes results.

There are three different changes that can occur on an Observable that the Observer reacts to. These are:

1.     Publishing a value
2.     Throwing an error
3.     Completed publishing all values

A class that implements the Observer interface must provide methods for each of the three changes above:

1.     An onNext() method that the Observable calls whenever it wishes to publish a new value
2.     An onError() method that’s called exactly once, when an error occurs on the Observable.
3.     An onCompleted() method that’s called exactly once, when the Observable completes execution.

Example: Display list of data using RxAndroid in to RecyclerView

First you have to import the dependencies  latest version of RxAndrod, RxJava and other like recyclerview, in to the build.gradle on app level inside the dependencies section.


Layout:
 RecyclerView is simply A flexible view for providing a limited window into a large data set.
activity_main.xml


and custom list item layout



Now, Obserable implement on MainActivity,



and Now implement RecyclerView Adapter



Output looks like:

Download full code from github: RxAndroid_RecyclerView_Example

Happy Coding!!!

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Different way of creating objects in Java or android

We know ,a class provides the blueprint for objects, so create an object from a class. Here are the some way of creating objects in java or android.

Here are some different ways to create objects in java:

1. Using new keyword
This is the most common way to create an object in java. Almost 99% of objects are created in this way.

 MyObject object = new MyObject();

2. Using Class.forName()
If we know the name of the class & if it has a public default constructor we can create an object in this way.

MyObject object = (MyObject) Class.forName("com.test").newInstance();

3. Using clone()
The clone() can be used to create a copy of an existing object.

MyObject newObject = new MyObject();
MyObject object = (MyObject) newObject.clone();

4. Using object deserialization
Object deserialization is nothing but creating an object from its serialized form.

ObjectInputStream objectInputStream = new ObjectInputStream(anInputStream );
MyObject object = (MyObject) objectInputStream.readObject();

5.Using newInstance() method of Constructor class
Similar to the newInstance() method of a Class, there is one newInstance() method in the java.lang.reflect.Constructor class, which we can use to create objects.

Constructor<User> myObject = User.class.getConstructor();
Employee emplyoeeObject = myObject.newInstance();

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Firebase Tutorial 2: Login in Android Application using Email and Password

Firebase is the a powerful platform for building iOS, Android, and web-based apps, offering real-time data storage and synchronization, user authentication, and more.

In this tutorials, we can learn how to login android application using firebase cloud platform. After develop the application, first we have to know how to configure android application in firebase, which is the basic thing of any android application start using fire. please read the above link.

To add Firebase to your app you'll need a Firebase project and a Firebase configuration file for your app.

1. Create a Firebase project in the Firebase console, if you don't already have one. If you already have an existing Google project associated with your mobile app, click Import Google Project. Otherwise, click Create New Project.
2. Click Add Firebase to your Android app and follow the setup steps. If you're importing an existing Google project, this may happen automatically and you can just download the config file.
3. When prompted, enter your app's package name. It's important to enter the package name your app is using; this can only be set when you add an app to your Firebase project.
4. At the end, you'll download a google-services.json file. You can download this file again at any time.
5. If you haven't done so already, copy this into your project's module folder, typically app/.

Then, in your module Gradle file (usually the app/build.gradle), add the authentication library in dependencies section.

com.google.firebase:firebase-auth:9.8.0

Now, In firebase, we know, there are many way to gives the user authentication like email/password, google, facebook, twitter, github and anonymous.

Lets start how to sign in using email/password.

After setting all the dependencies, you have to go project and left side there is Authentication section and go to sign-in method and enable the email/password section. Default it is disable, if you don't set the enable it won't work.

Now go to LoginActivity.java file,

Declare the FirebaseAuth and AuthStateListener objects. 

private FirebaseAuth mAuth; 

private FirebaseAuth.AuthStateListener mAuthListener;

In the onCreate() method, initialize the FirebaseAuth instance and the AuthStateListener method so you can track whenever the user signs in or out. 

mAuth = FirebaseAuth.getInstance();

firebaseAuthListener= new FirebaseAuth.AuthStateListener() {

            @Override

            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {

                FirebaseUser firebaseUser=firebaseAuth.getCurrentUser();

                if(firebaseUser!=null){

                    Log.e(TAG," onAuthStateChange: singed_in"+firebaseUser.getUid());

                }else{

                    Log.e(TAG," onAuthStateChange: singed_out");

                }

                updateUI(firebaseUser);

            }

        };

Attach the listener to your FirebaseAuth instance in the onStart() method and remove it on onStop(). 

@Override

    protected void onStart() {

        super.onStart();

        mAuth.addAuthStateListener(firebaseAuthListener);

    }

    @Override

    protected void onStop() {

        super.onStop();

        if(mAuth!=null){

            mAuth.addAuthStateListener(firebaseAuthListener);

        }

    }

For creating new user, we have to get the email and password from edittext and validates them and create new user with the createUserWithEmailAndPassword method.

// create new account

    public void createNewAccount(String email, String password){

        if(!validateForm()){

            return;

        }

        showProgressDialog();

        mAuth.createUserWithEmailAndPassword(email,password)

                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {

                    @Override

                    public void onComplete(@NonNull Task<AuthResult> task) {

                         if(!task.isSuccessful()){

                             Toast.makeText(LoginActivity.this,"User Create Sucessuflly", Toast.LENGTH_SHORT).show();

                         }

                        hideProgressDialog();

                    }

                });

    }

For sign in existing user,  get the email and password from edittext field and validates them and signs a user in with the signInWithEmailAndPassword method.

// sign in exising user

public  void singIn(String email, String password){

        if(!validateForm()){

            return;

        }

        showProgressDialog();

        mAuth.signInWithEmailAndPassword(email, password)

                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {

                    @Override

                    public void onComplete(@NonNull Task<AuthResult> task) {

                        if(!task.isSuccessful()){

                            Toast.makeText(LoginActivity.this,"User Login Failed", Toast.LENGTH_SHORT).show();

                            tvStatus.setText("Authentication Failed, Create New Account or Enter correct Credentials");

                        }

                        hideProgressDialog();

                    }

                });

    }

Yes, there is featues in firebase we can access the information about the signedIn user and there is a method getCurrentUser.

//geting user information

FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();

if (user != null) {

    // Name, email address.

    String name = user.getDisplayName();

  String email = user.getEmail();

}

Hope you will understand how to login using email/password. 

Please if you want more information about go to firebase doc.

Download Full Source

Happy Coding !!!

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Firebase Tutorial: 1. How to start firebase in android studio

Firebase is a mobile platform that helps you quickly develop high-quality apps, grow your user base, and earn more money. Firebase is made up of complementary features that you can mix-and-match to fit your needs.

Implementing Firebase is quick and easy. With spontaneous APIs packaged into a single SDK, you can focus on solving your customers' problems and not waste time building complex infrastructure.
Most Firebase features are free forever, for any scale. Firebase also handles large number hit and scaling server capacity.


Steps that you have to do integrate firebase in Android:Step 1. 
Go to https://console.firebase.google.com/   and Click on Create New Project.

Step 2.

Give the name of Project in project name field and select the country/region and click the button Create Project.

Step 3.

Then you will see the overview page, and this page you will choose Add firebase to your Android app.

Step 4.
Now, you will see the screen, where you put the  package name of android project, just copy from the androidmanifest.xml. and there optional section App nickname , you can put any nickname of your application. Next one is Debug signing certificate SHA-1  is also optional. and Click Add Project.

Step 5.

After Click Add project, google-services.json fill will automatically downloaded in you device. and Switch to the Project view in Android Studio to see your project root directory.

Move the google-services.json file you just downloaded into your Android app module root directory and click continue.

Step 6. 

Now, you have to add dependencies. Google services plugin for Gradle loads the google-services.json file you just downloaded. Modify your build.gradle files to use the plugin after adding all the dependencies click finish.

1. Project-level build.gradle (<project>/build.gradle):
   

   buildscript {
     dependencies {
       // Add this line
       classpath 'com.google.gms:google-services:3.0.0'
     }
   }

2. App-level build.gradle (<project>/<app-module>/build.gradle):
   

   ...
   // Add to the bottom of the file
   apply plugin: 'com.google.gms.google-services'

   includes Firebase Analytics by default help_outline
3. Finally, press "Sync now" in the bar that appears in the IDE:
   

Step 8.
Your firebase project is ready to use.You can use as your requirement.

Before start any android application, here is the some libraries are available for the various Firebase features(https://firebase.google.com/docs/android/setup) , you have to add on app/build.gradle.

Gradle Dependency Line	Service
com.google.firebase:firebase-core:9.6.1	Analytics
com.google.firebase:firebase-database:9.6.1	Realtime Database
com.google.firebase:firebase-storage:9.6.1	Storage
com.google.firebase:firebase-crash:9.6.1	Crash Reporting
com.google.firebase:firebase-auth:9.6.1	Authentication
com.google.firebase:firebase-messaging:9.6.1	Cloud Messaging and Notifications
com.google.firebase:firebase-config:9.6.1	Remote Config
com.google.firebase:firebase-invites:9.6.1	Invites and Dynamic Links
com.google.firebase:firebase-ads:9.6.1	AdMob
com.google.android.gms:play-services-appindexing:9.6.1	App Indexing

If you want to know more about firebase, Here is the useful video links
Firebase sample: https://firebase.google.com/docs/samples/
Firebase on Android - Tutorials: https://www.youtube.com/playlist?list=PLl-K7zZEsYLmxfvI4Ds2Atko79iVvxlaq
Getting started with Firebase and Android - Firecasts #1
Retrieving data in realtime with Firebase Events - Firecasts #2
Realtime RecyclerViews with FirebaseUI - Firecasts #3
Getting started with Firebase and Angular - Firecasts #4

Happy Coding !!!

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Most Frequently asked question and answers in interview for Android Developer

Most Frequently question and answers in interview for Android Developer, Here is the some of question and answers collection:

Android Interview Question/Answers and Tips

This answer provides a list of effective and commonly used Android interview questions . I have posted both the questions and answer .

1.What is the manifest file and how is it used?

Answer: Every Android app must have this manifest file in its root directory named ‘AndroidManifest.xml’. The file includes critical information about the app, including the Java package name for the application.

Bonus follow up question: What is the first element in the AndroidManifest file, right after the encoding declaration?

A: ‘manifest’ Note: The ‘permissions’ element is the next best answer if the developer assumed you meant the first element within the ‘manifest’ structure.

2. ways Android allows you to store data?

A: Any of the following 5 possible options are acceptable:

1.SharedPreferences

2.Internal Storage

3.External Storage

4.SQLite Database

5.Network connection

3.What items or folders are important in every Android project?

A: The developer should name at least 4 of these 6 items below, as these are essential within each Android project:

1. AndroidManifest.xml

2. build.xml

3. bin/

4. src/

5. res/

6. assets/

4.What is ANR?

A: ANR stands for “Application Not Responding”. It’s a dialog box that appears when an application doesn’t respond for more than 10 seconds (sometimes it can be less than 10 seconds). The ANR dialog box offers the user the option of either closing the app or waiting for it to finish running.

5. What is .apk extension?
A.The extension for an Android package file, which typically contains all of the files related to a single Android
application. The file itself is a compressed collection of an AndroidManifest.xml file, application code (.dex
files), resource files, and other files. A project is compiled into a single .apk file.

6. What is .dex extension?
A.Android programs are compiled into .dex (Dalvik Executable) files, which are in turn zipped into a single
.apk file on the device. .dex files can be created by automatically translating compiled applications written in
the Java programming language.

7. Explain the Architecture of Android ?
A. Top -> Applications (Contacts, Browser, Phone, etc)
Below Applications -> Application Framework(Activity Manager, Window Manager, Content Providers, View
System, Package manager,
Telephony manager, Resource, Notification, Location managers)
Below Application Framework -> System Libraries(Like Sqlite, webkit, SSL, OpenGL, Media Framework etc)
& Android Runtime( Core Libraries and DVM).
Atlast Last -> Linux Kernel (which composed of drivers like display, camera etc.)

10. What is an activity?
A. A single screen in an application, with supporting Java code.
An activity presents a visual user interface for one focused endeavor the user can undertake.
For example, an activity might present a list of menu items users can choose from or it might display
photographs along with their captions.

11. What is a service?
A.A service doesn’t have a visual user interface, but rather runs in the background for an indefinite period of time.
For example, a service might play background music as the user attends to other matters, or it might fetch data  over the network or calculate something and provide the result to activities that need it.Each service extends the Service base class.

12. How to Remove Desktop icons and Widgets?
A. Press and Hold the icon or widget. The phone will vibrate and on the bottom of the phone you will see  anoption to remove. While still holding the icon or widget drag it to the remove button. Once remove turns red  drop the item and it is gone

13. Describe a real time scenario where android can be used?
A .Imagine a situation that you are in a country where no one understands the language you speak and you can
not read or write. However, you have mobile phone with you.

14. Is there a unique Android device ID?
A: Settings.Secure#ANDROID_ID returns the Android ID as an unique 64-bit hex string.

import android.provider.Settings.Secure;

private String android_id = Secure.getString(getContext().getContentResolver(),
                                                        Secure.ANDROID_ID);

15. What languages does Android support for application development?
A.Android applications are written using the Java programming language.

16. Describe Android Application Architecture?
A.Android Application Architecture has the following components:
• Services – like N
• Intent – To perform inter-communication network Operation between activities or services
• Resource Externalization – such as strings and graphics
• Notification signaling users – light, sound, icon, notification, dialog etc

17. What is the Android Open Source Project?
A. We use the phrase “Android Open Source Project” or “AOSP” to refer to the people, the processes, and the source code that make up Android.

18. Why did we open the Android source code?
A .Google started the Android project in response to our own experiences launching mobile apps. We wanted to make sure that there would always be an open platform available for carriers, OEMs, and developers to use to  make their innovative ideas a reality. We also wanted to make sure that there was no central point of failure, so that no single industry player could restrict or control the innovations of any other. The single most important  goal of the Android Open-Source Project (AOSP) is to make sure that the open-source Android software is  implemented as widely and compatibly as possible, to everyone’s benefit.

19. What is a ContentProvider and what is it typically used for?

A: ContentProvider manages access to a structured set of data. It encapsulates the data and provide mechanisms for defining data security. ContentProvider is the standard interface that connects data in one process with code running in another process.

20. When does onResume() method called?
A: onResume() method is an activity lifecycle method. This is called when the activity come to foreground. You can override this method in your activity to execute code when activity is started, restarted or comes to foreground.

21. Will it work on my phone?
A.The app will work on all phones and tablets running Android version 1.6 and above.

22. How much does it cost?
A.The app is free and ad-supported.

23. How do I save the app to my SD card?
A. From the device's Settings menu, go to Applications > Manage applications > The Guardian. Under the data
header, choose "Move to SD card".

24. What is the use of WebView in android?
A : WebView is an android UI component that displays webpages. It can either display a remote webpage or can also load static HTML data. This encompasses the functionality of a browser that can be integrated to application. WebView uses the WebKit rendering engine to display web pages and includes methods to navigate forward and backward through a history, zoom in and out, etc.

25. How to get screen dimensions in pixels in Andorid Devices?
A: int screenHeight = getResources().getDisplayMetrics().heightPixels;
int screenWidth = getResources().getDisplayMetrics().widthPixels;

26. What is Mono for Android?
A. Mono for Android is a software development kit that allows developers to use the C# language to create  mobile applications for Android-based devices.Mono for Android exposes two sets of APIs, the core .NET APIs  that C# developers are familiar with as well as a C# binding to Android's native APIs exposed through the  Mono.Android.* namespace.You can use Mono for Android to develop applications that are distributed through  the Android Application Stores or to deploy software to your personal hardware or the Android simulator.

27. Difference between Activity Context and Application Context?
A:They are both instances of Context, but the application instance is tied to the lifecycle of the application, while the Activity instance is tied to the lifecycle of an Activity. Thus, they have access to different information about the application environment.

If you read the docs at getApplicationContext it notes that you should only use this if you need a context whose lifecycle is separate from the current context.

28. What is the difference between a fragment and an activity? Explain the relationship between the two?
A:An activity is typically a single, focused operation that a user can perform (such as dial a number, take a picture, send an email, view a map, etc.). Yet at the same time, there is nothing that precludes a developer from creating an activity that is arbitrarily complex.

Activity implementations can optionally make use of the Fragment class for purposes such as producing more modular code, building more sophisticated user interfaces for larger screens, helping scale applications between small and large screens, and so on. Multiple fragments can be combined within a single activity and, conversely, the same fragment can often be reused across multiple activities. This structure is largely intended to foster code reuse and facilitate economies of scale.

A fragment is essentially a modular section of an activity, with its own lifecycle and input events, and which can be added or removed at will. It is important to remember, though, that a fragment’s lifecycle is directly affected by its host activity’s lifecycle; i.e., when the activity is paused, so are all fragments in it, and when the activity is destroyed, so are all of its fragments.

29. What is 'Context' on Android?
A: Context of current state of the application/object. It lets newly-created objects understand what has been going on. Typically you call it to get information regarding another part of your program (activity and package/application).

You can get the context by invoking getApplicationContext(), getContext(), getBaseContext() or this (when in the activity class).

30. Where is the UI Designer?
A. Mono for Android does not bundle a UI designer to create the UI XML files We do not provide an
integrated UI designer in Mono for Android 1.0. No decisions past that have been made. We will be listening to user feedback to decide where to put resources for the future versions.

31. What is the difference between Service and IntentService? How is each used?
A: Service is the base class for Android services that can be extended to create any service. A class that directly extends Service runs on the main thread so it will block the UI (if there is one) and should therefore either be used only for short tasks or should make use of other threads for longer tasks.

IntentService is a subclass of Service that handles asynchronous requests (expressed as “Intents”) on demand. Clients send requests through startService(Intent) calls. The service is started as needed, handles each Intent in turn using a worker thread, and stops itself when it runs out of work. Writing an IntentService can be quite simple; just extend the IntentService class and override the onHandleIntent(Intent intent) method where you can manage all incoming requests.

32. What is the API profile exposed by Mono for Android?
A. Mono for Android uses the same API profile for the core libraries as MonoTouch.Specifically, MonoTouch  and Mono for Android both support a Silverlight-based API, without Silverlight's UI libraries (e.g. no XML, no WindowsBase.dll, etc.), and free of the sandboxing limitations of Silverlight.

33. Are the Android releases available in a ROM?
A. No, Android is not yet available in a ROM format.Currently Android is installed by using a clean SD Card, and booted from there.It is booted by running a special application called 'Haret.exe' residing on your SD Card  which will terminate the Windows kernel and boot into Linux/Android.It can't easily be run from ROM because  a) it's too experimental to risk putting in ROM and then killing a device and b) WinMo does some hardware  initialization that isn't documented, but is needed before Android can run.

34. When will it be available in a ROM?
A. No time soon. Folks are working on it, but you'll need a lot of patience before it (if ever) arrives

35. How do I turn off, or reboot Android?
A. In earlier releases, you had to pull the battery or press the reset button, in newer releases, you can hold down the 'end call' button and see a menu.

36. What is DDMS? Describe some of its capabilities.
A: DDMS is the Dalvik Debug Monitor Server that ships with Android. It provides a wide array of debugging features including:

• port-forwarding services
• screen capture
• thread and heap information
• network traffic tracking
• incoming call and SMS spoofing
• simulating network state, speed, and latency
• location data spoofing

37. What if my app uses location API, and service provider shuts that off, can they?
A. They can do that... it’s not a perfect world. Rather than having us dictate what carriers and OEMs support,
we let developers develop killer apps that will require it.
We want to ensure all the application development that goes on for Android... we want to give OEMs an
incentive to keep things open. It’s a positive, self fulfilling vision.

38.If I’m a game developer and I’m building piece of content and I want to sell it, how do I do that and realize revenue?
A. Content distribution — we’ve thought of that. It’d be great if there were a place where people could go to
safely download and pay for content.

39. We use SMS interception for system signalling. Is there a mechanism for an app to respond and stop the signaling chain? Is there security around that so that one vendor can’t hijack a message and respond to it?
A. There’s a mechanism where an application can register to receive a message with a certain signature and
prevent others from getting it. We have a system of permissions apps are able to declare, enforce, and require to
perform certain operations. Things like dial the phone, get to contacts, etc.. But these aren’t things that are
baked in the core of the system. An arbitrary app could declare custom permissions.
As far as restricting another app, the model we’ve been going by... the phone is not controlled by the
application vendor, it’s controlled by the user. Whether or not the permissions are granted is up to the user that
owns the phone. If you created a protocol that intercepts an SMS and another party wrote an app that intercepts
the same SMS and the user wants to use that, the user could be free to stick that in.

40. Can the user set a priority?
A. Don’t know, post your question to the developer’s community board.

41. Which of the code snippets below is the correct way to check if a Compass sensor is present on the system? Explain your answer.

Answer 1:

    PackageManager m = getPackageManager();
    if (!m.hasSystemFeature(PackageManager.FEATURE_SENSOR_COMPASS)) {
        // This device does not have a compass, turn off the compass feature
    }
Answer 2:

    SensorManager m = getSensorManager();
    if (!m.hasSystemFeature(SensorManager.FEATURE_SENSOR_COMPASS)) {
        // This device does not have a compass, turn off the compass feature
    }
Answer 3:

    Sensor s = getSensor();
    if (!s.hasSystemFeature(Sensor.FEATURE_SENSOR_COMPASS)) {
        // This device does not have a compass, turn off the compass feature
    }

42. What’s so special about Android?
A. Unlike the proprietary iPhone operating system (now known as "iOS,"), which is under the complete control of Apple — and the same goes for Research in Motion’s BlackBerry OS or Microsoft’s Windows Phone platform — Google released Android as an open-source OS under the auspices of the Open Handset Alliance,leaving phone manufacturers (relatively) free to tweak Android as they see fit for a given handset.

That’s one thing that’s special about Android. Another thing is that it just happens to be a really good OS, the first one in the post-iPhone wireless era to really give Apple a run for its money. Android may not be as sleek or polished as iOS (that’s my humble opinion, at least), but it’s fast and powerful, with an intuitive user interface that’s packed with options and flexibility. It’s also being constantly improved courtesy of the big brains at Google, making the Android experience sleeker by the day.

43. What is a portable wi-fi hotspot?
A:The portable wi-fi hotspot is used to share internet connection to other wireless devices.

44. What is NDK?
A. NDK stands for Native Development Kit. By using NDK, you can develop a part of app using native language such as C/C++ to boost the performance.

45. What is needed to make a multiple choice list with a custom view for each row?
A. Multiple choice list can be viewed by making the CheckBox android:id value be “@android:id /text1″. That is the ID used by Android for the CheckedTextView in simple_list_item_multiple_choice.

46. What are the life cycle methods of android activity?
A:There are 7 life-cycle methods of activity. They are as follows:

onCreate()
onStart()
onResume()
onPause()
onStop()
onRestart()
onDestroy()

47. Difference between px, sp, dip, dpi and pt in Android?
A: px is one pixel. px is corresponds to actual pixels on the screen.
sp is scale-independent pixels. SP is like the dp unit, but it is also scaled by the user's font size preference.
dip is Density-independent pixels.
dpi is Dots per inches.
pt is points.

48. What are the approaches required to share persistent user-defined objects?
A: Persistent objects come when there is process that is in the running state and the system can perform any action like restart or kill. If there is any data that will persist and required from another data then it is very essential to save it and share it so that if one activity is down, another activity can be performed without any hindrance. To share the complex persistent user-defined objects, it is required to have the approaches like:

- Application preferences: that is used to allow the user to change the setting of preferences and make it accessible by some other objects.
- Files: permissions on the files can be set so that any other file can also use and share the objects
- Content providers: allow easy to follow patterns that allow the user to select the object and share it with other functions.
- Database: the database can be used to store the user data and can easily link between the user and the entity that are present in it.

49.What are containers?

A: Containers holds objects and widgets together, depending on which items are needed and in what arrangement they need to be in. Containers may hold labels, fields, buttons, or even child containers, as examples.

50.What are App Widgets?

A: Also referred to simply as Widgets, App Widgets in the Android world are miniature views that are embedded within Android apps and typically display periodic updates. Music players, weather updates, sports scores, and stock price changes are all examples of data that can be displayed in an App Widget.

51. How will you record a phone call in Android? How to get a handle on Audio Stream for a call in Android?
A. Permissions.PROCESS_OUTGOING_CALLS: Allows an application to monitor, modify, or abort outgoing
calls.

52. Why cannot you run standard Java bytecode on Android?
A. Android uses Dalvik Virtual Machine (DVM) which requires a special bytecode. We need to convert Java
class files into Dalvik Executable files using an Android tool called "dx". In normal circumstances, developers
will not be using this tool directly and build tools will care for the generation of DVM compatible files.

53. Can you deploy executable JARs on Android? Which packaging is supported by Android?
A. No. Android platform does not support JAR deployments. Applications are packed into Android Package
(.apk) using Android Asset Packaging Tool (aapt) and then deployed on to Android platform. Google provides
Android Development Tools for Eclipse that can be used to generate Android Package.

54. Does android support other language than java?
A:Yes, android app can be developed in C/C++ also using android NDK (Native Development Kit). It makes the performance faster. It should be used with android SDK.

55. What is an action?
A. The Intent Sender desires something or doing some task

56. What are Dalvik Executable files?
A. Dalvik Executable files have .dex extension and are zipped into a single .apk file on the device.

57. How does Android system track the applications?
A. Android system assigns each application a unique ID that is called Linux user ID. This ID is used to track
each application.

58. When does Android start and end an application process?
A. Android starts an application process when application's component needs to be executed. It then closes the
process when it's no longer needed (garbage collection).

59. How can two Android applications share same Linux user ID and share same VM?
A. The applications must sign with the same certificate in order to share same Linux user ID and share same
VM.

60.  Write code snippet to retrieve IMEI number of Android phone.
A. TelephonyManager class can be used to get the IMEI number. It provides access to information about the telephony services on the device.
Code
        TelephonyManager mTelephonyMgr = (TelephonyManager)

        getSystemService(Context.TELEPHONY_SERVICE);

        String imei = mTelephonyMgr.getDeviceId();

61. How can I download the GoToMeeting app?
A. You can download the GoToMeetng app from the Android Market by signing in to your Google account
linked with your Android device and searching for the GoToMeeting app to install it. If you don’t see an Install
button, you may not be running Android 2.2 or higher – the minimum system requirement needed to install the
GoToMeeting app.
You can also download the GoToMeeting app from the Amazon Appstore (only available in the U.S.), which
lets you instantly download the GoToMeeting app to an Android device.
If you have the GoToMeeting app pre-loaded onto your device, you’ll need to first upgrade to the latest version
of GoToMeeting. To upgrade, select the GoToMeeting daisy icon and then select the Upgrade button to install
the most recent version of the app.

62.If I have a Motorola Android-based device that doesn’t have the Android Market app, can I still
download the GoToMeeting app?
A.Yes. Attendees using Motorola Android-based devices in China can now download the GoToMeeting app
from SHOP4APPSTM – Motorola’s preinstalled Android application storefront. The GoToMeeting app is not yet
localized in Chinese, but it is available in English, German, French, Spanish and Italian.

63.Is there a way to run Python on Android?
A:One way is to use Kivy:
- Open source Python library for rapid development of applications that make use of innovative user interfaces, such as multi-touch apps.
- Kivy runs on Linux, Windows, OS X, Android and iOS. You can run the same [python] code on all supported platforms.

64. How you can use built-in Messaging within your application?
A: You can use an Intent object to activate the built-in Messaging service. You have to pass MIME type “vnd.android-dir/mms-sms”, in setType method of Intent as shown in the following given below code.
Intent intent = new Intent (android.content.Intent.ACTION_VIEW);
intent.putExtra("address", "5556; 5558;");// Send the message to multiple recipient.
itent.putExtra("sms_body", "Hello my friends!");
intent.setType("vnd.android-dir/mms-sms");
startActivity(intent);

65. Does Android support Adobe Flash in the browser?
A.Flash support varies by device with Android 2.1. The Samsung Acclaim does not have Flash support upon
launch, but the HTC Desire will support Flash Lite 4.0 running Android 2.1. Flash 10.1 support is coming to
Android-powered phones with Android 2.2.

66.Does Android support push email or is it pull?
A. Android 2.1 supports push e-mail for Exchange mail and Gmail.

67. Will these phones have world phone capabilities, with the ability to make calls, receive data in other countries? Or will they be able to use Google Voice to make calls?
A.Our Android-powered phones have Wi-Fi which can be used abroad for data, including Google Voice for
making international calls. International Roaming for voice is available in several countries.

68. Will the App run on my Android phone?
A. Yes, our App is fully compatible with any Android phone running Android software v2.1 or later.

69. How do I install your App?
A. You can install our App from the Android Market by following the below steps:
Open the Android Market application in the Applications menu.
Hit the search icon and type in E.ON
To install it, hit the ‘Free’ button on the left hand side
In the next screen, it will give you more details about the application including the different functionalities it
will need to access. Just click on OK to finish installing the application.

70. How do I find and download updates to the E.ON Android application?
A. Any updates to our App will appear on your notification menu at the top of your screen. Just tap on the E. App icon and you'll be taken into the Android Market and be presented with the E.ON App download page.

71. What is a service in android?
The Service is like as an activity to do background functionalities without UI interaction.

72. What is an Intent?
A class (Intent) which describes what a caller desires to do. The caller will send this intent to Android's intent
resolver, which finds the most suitable activity for the intent. E.g. opening a PDF document is an intent, and the
Adobe Reader apps will be the perfect activity for that intent (class).

73. What is a Sticky Intent?
A. Sticky Intent is also a type of Intent which allows a communication between a function and a service
sendStickyBroadcast() performs a sendBroadcast(Intent) known as sticky, i.e. the Intent you are sending stays
around after the broadcast is complete, so that others can quickly retrieve that data through the return value of
registerReceiver(BroadcastReceiver, IntentFilter). In all other ways, this behaves the same as
sendBroadcast(Intent). One example of a sticky broadcast sent via the operating system is
ACTION_BATTERY_CHANGED. When you call registerReceiver() for that action -- even with a null
BroadcastReceiver -- you get the Intent that was last broadcast for that action. Hence, you can use this to find
the state of the battery without necessarily registering for all future state changes in the battery.

74. How the nine-patch Image different from a regular bitmap? Alternatively, what is the difference between nine-patch Image vs regular Bitmap Image?
A.It is one of a resizable bitmap resource which is being used as backgrounds or other images on the device.
The NinePatch class allows drawing a bitmap in nine sections. The four corners are unscaled; the middle of the
image is scaled in both axes, the four edges are scaled into one axis.

75. What is a resource?
A. user defined JSON, XML, bitmap, or other file, injected into the application build process, which can later be
loaded from code.

76.How will you record a phone call in Android? or How to handle an Audio Stream for a call in Android?
Permission.PROCESS_OUTGOING_CALLS: Will Allow an application to monitor, modify, or abort outgoing
calls. So using that permission we can monitor the Phone calls.

77.Does Android support the Bluetooth serial port profile?
Yes.

78. Can an application be started on powerup?
Yes.

79. How to Translate in Android?
The Google translator translates the data of one language into another language by using XMPP to transmit
data. You can type the message in English and select the language which is understood by the citizens of the
country in order to reach the message to the citizens.

80. Describe Briefly the Android Application Architecture
Android Application Architecture has the following components:
Services like Network Operation
Intent - To perform inter-communication between activities or servicesResource Externalization - such as
strings and graphics
Notification signaling users - light, sound, icon, notification, dialog etc.
Content Providers - They share data between applications

81. What is needed to make a multiple choice list with a custom view for each row?
A. Multiple choice list can be viewed by making the CheckBox android:id value be “@android:id /text1". That
is the ID used by Android for the CheckedTextView in simple_list_item_multiple_choice.

82. What dialog boxes are supported in Android ?Android supports 4 dialog boxes:
AlertDialog: An alert dialog box supports 0 to 3 buttons and a list of selectable elements, including
check boxes and radio buttons. Among the other dialog boxes, the most suggested dialog box is the alert
dialog box.
ProgressDialog: This dialog box displays a progress wheel or a progress bar. It is an extension of
AlertDialog and supports adding buttons.
DatePickerDialog: This dialog box is used for selecting a date by the user.
TimePickerDialog: This dialog box is used for selecting time by the user.

83.What are the notifications available in android?
A:
Toast Notification − It will show a pop up message on the surface of the window
Status Bar Notification − It will show notifications on status bar
Dialogue Notification − It is an activity related notification.

84.Features of Android:
Application framework enabling reuse and replacement of components
Dalvik virtual machine optimized for mobile devices
Integrated browser based on the open source WebKit engine
Optimized graphics powered by a custom 2D graphics library; 3D graphics based on the OpenGL ES 1.0
specification (hardware acceleration optional)
SQLite for structured data storage
Media support for common audio, video, and still image formats (MPEG4, H.264, MP3, AAC, AMR, JPG,PNG, GIF)
GSM Telephony (hardware dependent)
Bluetooth, EDGE, 3G, and WiFi (hardware dependent)
Camera, GPS, compass, and accelerometer (hardware dependent)
Rich development environment including a device emulator, tools for debugging, memory and performance
profiling, and a plugin for the Eclipse IDE.

85.What is an Application ?A. Collection of one or more activities, services, listeners, and intent receivers. An application has a single
manifest, and is compiled into a single .apk file on the device.

86.What is a Content Provider ?
A. A class built on ContentProvider that handles content query strings of a specific format to return data in a
specific format. See Reading and writing data to a content provider for information on using content providers.

87. What is a Dalvik ?
A. The name of Android’s virtual machine. The Dalvik VM is an interpreter-only virtual machine that executes
files in the Dalvik Executable (.dex) format, a format that is optimized for efficient storage and memory-
mappable execution. The virtual machine is register-based, and it can run classes compiled by a Java language
compiler that have been transformed into its native format using the included “dx” tool. The VM runs on top of
Posix-compliant operating systems, which it relies on for underlying functionality (such as threading and low
level memory management). The Dalvik core class library is intended to provide a familiar development base
for those used to programming with Java Standard Edition, but it is geared specifically to the needs of a small
mobile device.

88.What is an DDMS ?
A. Dalvik Debug Monitor Service, a GUI debugging application shipped with the SDK. It provides screen
capture, log dump, and process examination capabilities.

89.What is Drawable?
A. A compiled visual resource that can be used as a background, title, or other part of the screen. It is compiled
into an android.graphics.drawable subclass.

90.What are fragments in Android Activity ?
A. Fragment represents a behavior or a portion of user interface in an Activity. And it is a self-contained
component with its own UI and lifecycle.

91. What is Service?
A. Service doesn't have a visual user interface , but rather runs in the background for an indefinite period of
time. For Example, a service might play background for music as the user attends to other matters.

92. What is BroadReceivers?
A. BroadcastReceiver is a component that does nothing but receive and react to broadcast announcements.
For example, the battery is low or that the user changed a language preference.

93.How do you avoid an ANR?

A: A follow-up to the previous question, there are a number of possible answers here. What you want to hear is that you want as little work done as possible on the main thread, also known as the “UI thread”. Since that is the core single thread that your application runs on, you would want to keep activities that require more complex computations or network and database connections, for example, on separate worker threads so as not to slow down the main thread.

94.How many ways data stored in Android?
1.SharedPreferences
2.Internal Storage
3.External Storage
4.SQLite Database
5.Network connection

95. Types of Android applications?
1.Foreground
2.Background
3.Intermittent
4.Widget

96. Android Development Tools?
A. The Android SDK and Virtual Device Manager Used to create and manage Android Virtual Devices (AVD)
and SDK packages.
The Android Emulator An implementation of the Android virtual machine designed to run within a virtual
device on your development computer. Use the emulator to test and debug your Android applications.
Dalvik Debug Monitoring Service(DDMS) Use the DDMS perspective to monitor and control the Dalvik virtual
machines on which your debugging your application.
Android Asset Packaging Tool(AAPT) Constructs the destributable Android packages files (.apk).
Android Debug Bridge(ADB) A client-server application that provedes a link to a running emulator.It lets you
copy files, install compiled application packages(.apk),and run shell commands.

97.What is View in Android?
A. Views are the base class for all visual interface elements(commonly known as controls or widgets).
All UI controls,including the layout classes,are derived for View.

98. What View Group in Android?
A. View Groups are extensions of the View class that can contain multiple child View.Extend the ViewGroupclass to create compound controls made up of interconnected child Views.

99.What information do you need before you begin coding an Android app for a client?

A: You want to find out that this person will seek to truly understand what you are trying to accomplish with your app, and the functionality. The following items are good to hear:

• Objective statement or purpose of the app for the app publisher
• Description of the target audience or user demographics
• Any existing apps that it might be similar to
• Wireframes
• Artwork; 

100.What is the difference between match_parent and fill_parent?
A: They're the same thing (in API Level 8+). Use match_parent.

FILL_PARENT (renamed MATCH_PARENT in API Level 8 and higher), which means that the view wants to be as big as its parent (minus padding)

fill_parent: The view should be as big as its parent (minus padding). This constant is deprecated starting from API Level 8 and is replaced by match_parent



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It is also include above, some are missing please don't forget to solve this also:

• What is Activity?
• Activity life cycle? (Example when app come from background to foreground which method get called?)
• What is Fragment?
• Fragment life cycle?
• Interface and it's importance?
• Application State and how does it save data during your app session?
• What are benefit of Shared preference?
• Services in Android?
• How to make list view scroll smoothly? ( e.g Viewholder pattern.. )
• What layout does paytm use mainly?  (Linear or Relative,  Of course Relative layout)
• Difference between Thread and Handler?
• Asynchronous Task and Threads?
• Sqlite and content provider?
• Polymorphism? 
• Inheritance?
• Difference between Interface and Abstract Class?
• Synchronized this keyword meaning?
• Hashmap and LinkedHaspmap and dynamic array?
• Bundle?
• How does HttpRequest for calling an API from server,  works ?
• BroadCastReceiver?
• Frame layout?
• Horizontal and Vertical Scroll?
• Tab layout?
• View pager?

Happy Coding !!! 

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