Dependency injection is one theory that creates a class independent of building the instances of needed functionalities of other classes. DI can disassociate the handling of instances from its construction.<\/p>\n\n\n\n
The illustration of this technique is done by using the Dagger<\/strong> dependency injection framework. Dagger is a simple DI(Dependency Injection) tool to manage dependencies. Dagger is performed using Java’s annotations<\/strong> model.<\/p>\n\n\n\n Dagger will provide necessary objects. And gives us a service to inject these objects. On the other hand, it leads to the lifetime of the objects. That also assists us to create a clean code.<\/p>\n\n\n\n The Finest way of implementing the Dependency Injection is \u201cHILT<\/strong>\u201d in android development. The built area of the hilt is at the top of the dagger.<\/p>\n\n\n\n Hilt is only used for android development. Hilt also created the dagger code behind the scenario of code generation. We can also call the advanced version of \u201cDagger\u201d.<\/p>\n\n\n\n The first and main important thing about the hilt is that Hilt is very easy compared to the dagger android<\/a><\/strong>. Hilt is given some predefined work that turns hilt into easy implementation for dependency injection.<\/p>\n\n\n\n There is a list of annotations that are provided by hilt for dependency injection:<\/p>\n\n\n\n @HiltAndroidApp<\/strong>,@Module<\/strong>,@InstallIn<\/strong>,@Provides<\/strong>,@Singleton<\/strong>, @HiltViewModel<\/strong>, @Inject<\/strong>, @Named<\/strong>.<\/p>\n\n\n\n You should have clear the fundamentals of Android<\/strong>.<\/p>\n\n\n\n you should have some basic knowledge of what MVVM is and how MVVM architecture<\/a><\/strong> works in android. <\/p>\n\n\n\n You should have experience with anyone language properly, either Kotlin or Java.<\/p>\n\n\n\n Also, you should have a good understanding of OOPs concepts.<\/p>\n\n\n\n And basic ideas about annotations.<\/p>\n\n\n\n Don\u2019t worry, there are only 7 simple steps for learning dagger-hilt implementation.<\/p>\n\n\n\n Create one project and give it whatever name you want.<\/p>\n\n\n\n After creating the project, set up the dependency work. Without dependencies, we can not implement or run the hilt in our android application<\/a>.<\/p>\n\n\n\n Creating one application class. This application class will provide the needed context in some parts of coding. Use one annotation of hilt, that is @HiltAndroidApp this will look like the following :<\/p>\n\n\n\n If in case of you will not provide this Application class then you will get some errors like this:<\/p>\n\n\n\n And remember one thing, you should set up the name of your application class in the manifest file.<\/p>\n\n\n\n We will create one data class Car in this step.<\/p>\n\n\n\n After that in the parameter of the data class, we will pass one parameter called carName <\/strong>and take it as a string.<\/p>\n\n\n\n After that, the Next step is about the creating our module class, In this demo project we will create a module class and give it a name like CarModule.kt<\/strong><\/p>\n\n\n\n We will take it as an object, And above that, we will put two annotations, one is @Module, and the second is @InstallIn<\/strong>. We have used @Module <\/strong>annotation because that annotation will notify us that this is a module class. In @InstallIn<\/strong> annotation, we will use SingletonComponent::class<\/strong> as a parameter that will create a ComponentFactory class in the background. As a SingletonComponent <\/strong>class, there is also one class as ActivityComponent::class <\/strong>this class works in activities. If you use your dependencies in the overall project then you can use the SingletonComponent <\/strong>class otherwise you can use ActivityComponent <\/strong>class. Like activity hilt also provides the component class for fragments. And this is called FragmentComponent::class. <\/strong>That all component classes work on their hierarchy. For knowing the hierarchy of component classes prefer this link to the official documentation of Android<\/a><\/strong>.<\/p>\n\n\n\n This module class has all the dependency functions that will be injected into consumer classes. Here in the demo prThis module class has all the dependency functions that will be injected into consumer classes. Here in the demo project, we have two dependency functions. <\/strong>On that function, we use some annotations like @Provides<\/strong> annotation and @Singleton<\/strong> annotation. @Provides<\/strong> annotation has use for providing the dependencies to inject annotations. @Singleton<\/strong> annotation creates a single object in the project and uses that for all classes. This annotation is very helpful when you don’t create more than one object of dependencies.<\/p>\n\n\n\n As you see here, there are two functions providingTheRacingCar<\/strong> and providingTheSimpleCar<\/strong>. Both functions provide two car\u2019s names. You see there is one other annotation @Named<\/strong>, this annotation is very helpful for developers in doing their tasks. For Example, you can see there are two methods and they both provide a car name so hilt will be confused at that time. In this case, @Named<\/strong> will help to choose specific dependencies for specific @injection<\/strong>. Otherwise, hilt will be confused to choosing dependencies.<\/p>\n\n\n\n Now here, In this step, we have taken MainActivity <\/strong>as an entry point of hilt dependency injection. Here @AndroidEntryPoint <\/strong>annotation is helpful to do this work of creating entry points to a class. This will provide us with hilt in various class.<\/p>\n\n\n\n After knowing the @AndroidEntryPoint, <\/strong>we will create one lateinit var object called as racingCar and give his type as Car <\/strong>data class. And then we will inject the car dependency directly in racingCar . That will be possible by using @Inject <\/strong>annotation of hilt. Here hilt will get confused about which dependency to choose from as there are two functions in the module class that provides Car objects. So simply we have used the @Named to specify that we choose only racing car strings. For that, we have already given the Name as CarStringFirst to that string dependency.<\/p>\n\n\n\n If we have to choose a simple car name then we will inject the CarStringSecond to that object. And then We have to log that object for testing. If an object is injected successfully then the value of that dependency is shown in Logcat. Otherwise, logcat does not show that value. Here in MainActivity, We have also used one ViewModel that we will Know in the next step.<\/p>\n\n\n\n In this step,We will create one ViewModel <\/strong>class.<\/p>\n\n\n\n In the above code you can see, we have used one annotation called @HiltViewModel.<\/strong> This annotation is used for telling the hilt that this class is viewmodel class so treat that class as viewmodel class. Normally in other classes we use dependency injection directly, But here in this viewmodel class we can not do that method. In ViewModel, <\/strong>we can inject the dependencies in the constructor only. And after that injection we have used that required dependencies in the viewmodel class.<\/p>\n\n\n\n In this CarViewModel <\/strong>we have injected the dependency whose name is CarStringSecond<\/strong>. So that will give the value of a simple car function. And this code we have log that object which has injected the dependency of car string. After that we will run and check that logs in logcat and they all show our provided values.<\/p>\n\n\n\n By considering this project we will conclude that hilt is a very standard way to implement the dependency injection in android development<\/a><\/strong>. By this example, we can understand how the dagger-hilt is implemented in android development. And we can relate the dagger and dagger-hilt easily. Accelerate your app development with our team of expert android developers<\/a><\/strong> who bring your ideas to life.<\/p>\n\n\n\n Dagger-hilt has provided a standard way to implement the dependency injection in android application development. On the other hand, Dagger is used for handling a complex scenario compared to hilt.<\/p> <\/div> In dagger, we have to create some component classes but hilt that is already provided. You have to only use their annotation and this will work.<\/p> <\/div> <\/div>\n","protected":false},"excerpt":{"rendered":" Introduction First of all, we’ll know about DI (Dependency Injection) because by knowing the DI, we can better understand or relate the Dagger hilt in android development. So the simple meaning of Dependency is, suppose that there is one class of students and another class called college. Here student class is dependent on class college. …<\/p>\n","protected":false},"author":77,"featured_media":54652,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[516,838],"tags":[901,795,1225],"class_list":["post-50459","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-mobile-apps","category-solutions","tag-android","tag-mobile-app-development","tag-use-dagger-hilt-in-android"],"yoast_head":"\n![\"Android](\"https:\/\/www.oneclickitsolution.com\/blog\/wp-content\/uploads\/2021\/12\/Android-Custom-Library-CTA2.png\")
<\/a><\/figure>\n\n\n\nHilt – The wrapper library on the dagger<\/h2>\n\n\n\n
Why is it important?<\/h2>\n\n\n\n
Essential knowledge to implement dagger-hilt in android:<\/h2>\n\n\n\n
Quickly, let’s take one demo project of implementing dagger-hilt in android:<\/h2>\n\n\n\n
Step 1<\/h3>\n\n\n\n
![\"create](\"https:\/\/www.oneclickitsolution.com\/blog\/wp-content\/uploads\/2022\/05\/create-one-project.png\")
<\/figure>\n\n\n\nStep 2<\/h3>\n\n\n\n
build.gradleI(:app)\nplugins {\n id 'com.android.application'\n id 'org.jetbrains.kotlin.android'\n id 'kotlin-kapt'\n id 'dagger.hilt.android.plugin'\n}\ndependencies {\n implementation 'androidx.core:core-ktx:1.7.0'\n implementation 'androidx.appcompat:appcompat:1.4.1'\n implementation 'com.google.android.material:material:1.5.0'\n implementation 'androidx.constraintlayout:constraintlayout:2.1.3'\n testImplementation 'junit:junit:4.13.2'\n androidTestImplementation 'androidx.test.ext:junit:1.1.3'\n androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'\n\n \/\/hilt\n implementation \"com.google.dagger:hilt-android:2.38.1\"\n kapt \"com.google.dagger:hilt-compiler:2.38.1\"\n implementation \"androidx.activity:activity-ktx:1.4.0\"\n}\n\t\t\nbuild.gradleI(:project)\n\nbuildscript {\n repositories {\n google()\n mavenCentral()\n }\n dependencies {\n classpath 'com.google.dagger:hilt-android-gradle-plugin:2.38.1'\n }\n}\n<\/code><\/pre>\n\n\n\nStep 3<\/h3>\n\n\n\n
package com.example.blog\n\nimport android.app.Application\nimport dagger.hilt.android.HiltAndroidApp\n\n@HiltAndroidApp\nclass CarApplication:Application()<\/code><\/pre>\n\n\n\n![\"provide](\"https:\/\/www.oneclickitsolution.com\/blog\/wp-content\/uploads\/2022\/05\/provide-this-application-class.png\")
<\/figure>\n\n\n\n<?xml version=\"1.0\" encoding=\"utf-8\"?>\n<manifest xmlns:android=\"http:\/\/schemas.android.com\/apk\/res\/android\"\n package=\"com.example.blog\">\n\n <application\n android:name=\".CarApplication\"\n android:allowBackup=\"true\"\n android:icon=\"@mipmap\/ic_launcher\"\n android:label=\"@string\/app_name\"\n android:roundIcon=\"@mipmap\/ic_launcher_round\"\n android:supportsRtl=\"true\"\n android:theme=\"@style\/Theme.Blog\">\n <activity\n android:name=\".MainActivity\"\n android:exported=\"true\">\n <intent-filter>\n <action android:name=\"android.intent.action.MAIN\" \/>\n\n <category android:name=\"android.intent.category.LAUNCHER\" \/>\n <\/intent-filter>\n <\/activity>\n <\/application>\n\n<\/manifest><\/code><\/pre>\n\n\n\nStep 4<\/h3>\n\n\n\n
package com.example.blog\ndata class Car(\n val carName:String\n)<\/code><\/pre>\n\n\n\nStep 5<\/h3>\n\n\n\n
package com.example.blog\n\nimport android.content.Context\nimport dagger.Module\nimport dagger.Provides\nimport dagger.hilt.InstallIn\nimport dagger.hilt.android.qualifiers.ApplicationContext\nimport dagger.hilt.components.SingletonComponent\nimport javax.inject.Named\nimport javax.inject.Singleton\n@Module\n\/**\n* ApplicationComponent is deprecated now.\n* So instead of this,now use \"SingletonComponent\".\n*\/\n@InstallIn(SingletonComponent::class)\nobject CarModule {\n\n @Provides\n @Singleton\n @Named(\"CarStringFirst\")\n fun providingTheRacingCar() = Car(\"Ferrari\")\n\n @Provides\n @Singleton\n @Named(\"CarStringSecond\")\n fun providingTheSimpleCar(@ApplicationContext context: Context): Car =\n Car(context.getString(R.string.inject_string))\n}<\/code><\/pre>\n\n\n\nStep 6<\/h3>\n\n\n\n
package com.example.blog\n\nimport androidx.appcompat.app.AppCompatActivity\nimport android.os.Bundle\nimport android.util.Log\nimport androidx.activity.viewModels\nimport androidx.lifecycle.ViewModel\nimport dagger.hilt.android.AndroidEntryPoint\nimport javax.inject.Inject\nimport javax.inject.Named\n@AndroidEntryPoint\nclass MainActivity : AppCompatActivity() {\n @Inject\n @Named(\"CarStringFirst\")\n lateinit var racingCar: Car\n\n private val viewModel : CarViewModel by viewModels()\n\n override fun onCreate(savedInstanceState: Bundle?) {\n super.onCreate(savedInstanceState)\n setContentView(R.layout.activity_main)\n\n Log.d(\"MainActivity\",\"The Racing car form Activity class:-${racingCar.toString()}\")\n\n viewModel\n }\n}\n<\/code><\/pre>\n\n\n\nStep 7<\/h3>\n\n\n\n
package com.example.blog\n\nimport android.util.Log\nimport androidx.lifecycle.ViewModel\nimport dagger.hilt.android.lifecycle.HiltViewModel\nimport javax.inject.Inject\nimport javax.inject.Named\n\n\/**\n* Now, you can not use '@ViewModelInject' annotation,\n* because this is deprecated right now.\n* So, Use '@HiltViewModel' above the class declaration and Inject as normal as other constructor injection method.\n*\/\n@HiltViewModel\nclass CarViewModel @Inject constructor( @Named(\"CarStringSecond\") simpleCar : Car ) : ViewModel() {\n\n init {\n Log.d(\"CarViewModelLog\", \"Simple car from ViewModel:- ${simpleCar.toString()}\")\n }\n}\n<\/code><\/pre>\n\n\n\nFirst Log:<\/h4>\n\n\n\n
![\"First](\"https:\/\/www.oneclickitsolution.com\/blog\/wp-content\/uploads\/2023\/03\/first-log.webp\")
<\/figure>\n\n\n\nSecond Log:<\/h4>\n\n\n\n
![\"Second](\"https:\/\/www.oneclickitsolution.com\/blog\/wp-content\/uploads\/2023\/03\/second-log.webp\")
<\/figure>\n\n\n\nConclusion<\/h2>\n\n\n\n
![\"Android](\"https:\/\/www.oneclickitsolution.com\/blog\/wp-content\/uploads\/2021\/12\/Android-Custom-Library-CTA1.png\")
<\/a><\/figure>\n\n\n\nFAQs<\/h2>\n\n\n\n