Android

This post demonstrates the Android chat application leveraging Azure Communication Services and ChatKit.

Kotlin supports Higher order functions. In this blog, I will create a higher order function that will use map & fold right for execution. Before diving into higher order functions, let’s go through map & fold right. map is collective transform operation. var numbers = mutableListOf(1, 2, 3) numbers = numbers.map { it*2 }.toMutableList() // elements in numbers: 2,4,6 foldRight accept initial state, apply initial state to all elements and return final state. var numbers = mutableListOf(1, 2, 3) var result = numbers.foldRight(100, {a,b -> test(a,b)}) private fun test(a: Int, b: Any): Int { return a + b as Int } /* First execution: initial 100 a = 3 b = 100 Second Execution a = 2 b = 103 Third Execution a = 1 b = 105 final: result = 106 */ Let’s create a higher order function Middleware that takes an instance StringApp, has inner function next: Type and return Type. ...

It is very connivent to use any DI framework when all the objects required are available in application. For example, I have two classes Logger, Service and class Middleware is dependent on these classes. class Logger() class Service() //this class requires Logger & Service object class Middleware(private val logger:Logger. private val service:Service) // middleware object val middleware = Middleware(Logger(),Service()) Dagger can build objects of Logger and Service classes by indicating @Inject annotation to all three classes internal class Logger @Inject constructor() internal class Service @Inject constructor() //this class requires Logger & Service object internal class Middleware @Inject constructor(private val logger:Logger. private val service:Service) @Component interface MiddlewareComponent { fun buildComponent():Middleware } // middleware object val middleware = DaggerMiddlewareComponent.builder().build().buildComponent() If the project requirements are modified to get Logger with custom implementation, we can write @Module to support dependency injection. // now, Logger is interface interface Logger class Service @Inject constructor() class Middleware @Inject constructor(val logger: Logger, val service: Service) @Module class LoggerModule constructor(val logger: Logger) { @Provides fun providesLogger(): Logger { return logger } } @Component(modules = [LoggerModule::class]) interface MiddlewareComponent { fun buildComponent(): Middleware } //custom implementation class NullLogger : Logger //injecting logger module with interface implementation val middleware = DaggerMiddlewareComponent.builder().loggerModule(LoggerModule(NullLogger())).build().buildComponent()

Below are widely used Dependency Injection frameworks mostly by android & Java application projects. For Android application development, the suggested Framework by Google are Dagger and Hilt. These frameworks help to avoid writing boilerplate code. Guice Guice (pronounced ‘juice’) is a lightweight dependency injection framework for Java 6 and above, brought to you by Google. (github.com) With 10K stars this framework is mostly used by Java developers where Java is used for backend & Application development. For Android, this framework is not suggested as this framework use reflections to scan annotations from code. This requires significant CPU cycles and RAM thus slowdowns application launch. Reflection on the desktop/server JVM is very efficient, and even very large Guice applications don’t have performance problems related to Guice. Manage your app’s memory | Android Developers : Other dependency injection frameworks that use reflection tend to initialize processes by scanning your code for annotations. This process can require significantly more CPU cycles and RAM and can cause a noticeable lag when the app launches. ...

Recently, I developed an Android application. The application was developed focusing on simplicity. The application was small thus skipped writing unit tests. I know skipping the unit tests is not a good practice. In past, I was working on backend projects where tons of unit tests exists for API’s. I am new to application development and spent some time to learn about MVC and MVVM design patterns. For next project, the preference is MVVM. At end of this post I will share the reason to choose MVVM. The example code for this post is written for Android application. MVC (Model-View-Controller) Model: Model is data layer. Model call services or database to get data from external systems. View: View is user interface layer. Controller: Controller is triggered first. Controller has reference to Model as well as View. Controller get data from Model and send to View. ...

In this post, I am writing about how to setup Azure Active Directory Android application login to access Azure functions protected with Azure Active Directory authentication. Create an Android Application Open Android Studio and create new Project with Empty Activity. Configure project with below settings Get SHA1 & package name Open powershell and cd to C:\Users<username>.android Execute below command, if prompted for password enter android or leave blank keytool -list -v -keystore debug.keystore -alias androiddebugkey -storepass android -keypass android Copy SHA1 -> Navigate to https://base64.guru/converter/encode/hex and convert SHA1 to Base64 Copy package name from AndroidManifest.xml Now you have packagename & Base64 SHA1 hash Setup Azure Active Directory I followed steps from Register your app under Azure Active Directory (using Android platform settings) to setup AAD. Login to Azure Open AAD Click App Registration -> New Registration Select Authentication Select Add a platform Enter SHA1 Hash & package name Copy Android Configuration ...

Checkstyle is a development tool to help programmers write Java code that adheres to a coding standard. Steps to enable checkstyle for Android Project Create checkstyle.xml Create folder checkstyle inside Android Project app folder. Create file checkstyle.xml Reference <?xml version="1.0"?> <!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.2//EN" "http://www.puppycrawl.com/dtds/configuration_1_2.dtd"> <!-- Checkstyle configuration that checks the sun coding conventions from: - the Java Language Specification at http://java.sun.com/docs/books/jls/second_edition/html/index.html - the Sun Code Conventions at http://java.sun.com/docs/codeconv/ - the Javadoc guidelines at http://java.sun.com/j2se/javadoc/writingdoccomments/index.html - the JDK Api documentation http://java.sun.com/j2se/docs/api/index.html - some best practices Checkstyle is very configurable. Be sure to read the documentation at http://checkstyle.sf.net (or in your downloaded distribution). Most Checks are configurable, be sure to consult the documentation. To completely disable a check, just comment it out or delete it from the file. Finally, it is worth reading the documentation. --> <module name="Checker"> <!-- If you set the basedir property below, then all reported file names will be relative to the specified directory. See http://checkstyle.sourceforge.net/5.x/config.html#Checker <property name="basedir" value="${basedir}"/> --> <!-- Checks that a package-info.java file exists for each package. --> <!-- See http://checkstyle.sf.net/config_javadoc.html#JavadocPackage --> <module name="JavadocPackage"/> <!-- Checks whether files end with a new line. --> <!-- See http://checkstyle.sf.net/config_misc.html#NewlineAtEndOfFile --> <module name="NewlineAtEndOfFile"/> <!-- Checks that property files contain the same keys. --> <!-- See http://checkstyle.sf.net/config_misc.html#Translation --> <module name="Translation"/> <!-- Checks for Size Violations. --> <!-- See http://checkstyle.sf.net/config_sizes.html --> <module name="FileLength"/> <!-- Checks for whitespace --> <!-- See http://checkstyle.sf.net/config_whitespace.html --> <module name="FileTabCharacter"/> <!-- Miscellaneous other checks. --> <!-- See http://checkstyle.sf.net/config_misc.html --> <module name="RegexpSingleline"> <property name="format" value="\s+$"/> <property name="minimum" value="0"/> <property name="maximum" value="0"/> <property name="message" value="Line has trailing spaces."/> </module> <module name="TreeWalker"> <!-- Checks for Javadoc comments. --> <!-- See http://checkstyle.sf.net/config_javadoc.html --> <module name="JavadocMethod"/> <module name="JavadocType"/> <module name="JavadocVariable"/> <module name="JavadocStyle"/> <!-- Checks for Naming Conventions. --> <!-- See http://checkstyle.sf.net/config_naming.html --> <module name="ConstantName"/> <module name="LocalFinalVariableName"/> <module name="LocalVariableName"/> <module name="MemberName"/> <module name="MethodName"/> <module name="PackageName"/> <module name="ParameterName"/> <module name="StaticVariableName"/> <module name="TypeName"/> <!-- Checks for Headers --> <!-- See http://checkstyle.sf.net/config_header.html --> <!-- <module name="Header"> --> <!-- The follow property value demonstrates the ability --> <!-- to have access to ANT properties. In this case it uses --> <!-- the ${basedir} property to allow Checkstyle to be run --> <!-- from any directory within a project. See property --> <!-- expansion, --> <!-- http://checkstyle.sf.net/config.html#properties --> <!-- <property --> <!-- name="headerFile" --> <!-- value="${basedir}/java.header"/> --> <!-- </module> --> <!-- Following interprets the header file as regular expressions. --> <!-- <module name="RegexpHeader"/> --> <!-- Checks for imports --> <!-- See http://checkstyle.sf.net/config_import.html --> <module name="AvoidStarImport"/> <module name="IllegalImport"/> <!-- defaults to sun.* packages --> <module name="RedundantImport"/> <module name="UnusedImports"/> <!-- Checks for Size Violations. --> <!-- See http://checkstyle.sf.net/config_sizes.html --> <module name="LineLength"/> <module name="MethodLength"/> <module name="ParameterNumber"/> <!-- Checks for whitespace --> <!-- See http://checkstyle.sf.net/config_whitespace.html --> <module name="EmptyForIteratorPad"/> <module name="GenericWhitespace"/> <module name="MethodParamPad"/> <module name="NoWhitespaceAfter"/> <module name="NoWhitespaceBefore"/> <module name="OperatorWrap"/> <module name="ParenPad"/> <module name="TypecastParenPad"/> <module name="WhitespaceAfter"/> <module name="WhitespaceAround"/> <!-- Modifier Checks --> <!-- See http://checkstyle.sf.net/config_modifiers.html --> <module name="ModifierOrder"/> <module name="RedundantModifier"/> <module name="AvoidNestedBlocks"/> <module name="EmptyBlock"/> <module name="LeftCurly"/> <module name="NeedBraces"/> <module name="RightCurly"/> <module name="AvoidInlineConditionals"/> <module name="DoubleCheckedLocking"/> <!-- MY FAVOURITE --> <module name="EmptyStatement"/> <module name="EqualsHashCode"/> <module name="HiddenField"/> <module name="IllegalInstantiation"/> <module name="InnerAssignment"/> <module name="MagicNumber"/> <module name="MissingSwitchDefault"/> <module name="RedundantThrows"/> <module name="SimplifyBooleanExpression"/> <module name="SimplifyBooleanReturn"/> <module name="DesignForExtension"/> <module name="FinalClass"/> <module name="HideUtilityClassConstructor"/> <module name="InterfaceIsType"/> <module name="VisibilityModifier"/> </module> </module> Create checkstyle.gradle Create checkstyle.gradle inside app folder (at same level where build.gradle exists) ...