Develop Reference

Android studio throws a duplicate class error when annotationProcessor is added

I recently just started with android development using kotlin so a total noob at android studio too.
I am trying to build a super simple HelloWorld app but I got this error:
Annotation processors must be explicitly declared now. The following dependencies on the compile classpath are found to contain annotation processor. Please add them to the annotationProcessor configuration.
- jetified-kotlin-compiler-embeddable-1.3.72.jar (kotlin-compiler-embeddable-1.3.72.jar)
Alternatively, set android.defaultConfig.javaCompileOptions.annotationProcessorOptions.includeCompileClasspath = true to continue with previous behavior. Note that this option is deprecated and will be removed in the future.
See https://developer.android.com/r/tools/annotation-processor-error-message.html for more details.
but when I added the annotationprocessor at the end of my dependencies like:
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'androidx.core:core-ktx:1.2.0'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test.ext:junit:1.1.1'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
annotationProcessor "org.jetbrains.kotlin:kotlin-compiler-embeddable:$kotlin_version"
}
I encountered a new error instead when I tried to build:
https://del.dog/pyfunestin

Class duplicate error can be solved by cleaning the project. First clean the project and rebuild it.

Firebase UI Database Implementation

Tried to add Firebase UI implementation
implementation 'com.firebaseui:firebase-ui-database:6.2.0'
in build.gradle file.
The following error was shown.
*ERROR: Unable to resolve dependency for ':app#debug/compileClasspath': Could not resolve com.firebaseui:firebase-ui-database:6.2.0.
Affected Modules: app*
Please guide me how to resolve the issue.
I am using Android Studio 3.5.3
Other dependencies I have already implemented in the app
implementation 'com.google.firebase:firebase-auth:16.0.5'
implementation 'com.google.firebase:firebase-database:16.0.4'

You need to update the following dependencies:
implementation 'com.google.firebase:firebase-auth:16.0.5'
implementation 'com.google.firebase:firebase-database:16.0.4'
to
implementation 'com.google.firebase:firebase-auth:19.2.0'
implementation 'com.google.firebase:firebase-database:19.2.0
Also upgrade to androidX. Check the following for more information:
From the docs:
FirebaseUI version 6.0.0 has no breaking API changes from version 5.1.0 but updates critical dependencies to new major versions.
There are two major groups of changes:
Convert all Android Support Library dependencies to AndroidX or Jetpack dependencies. For information on migrating to AndroidX see this guide.
Update all Firebase and Google Play services dependencies to their latest major versions. For information on changes included in these SDKs visit the release notes.

You can follow these steps:
Press F4 to open Module settings
Select Dependency
Click Add new dependency
Type firebase, search for firebase.ui and add its latest dependency.

At last I was able to sync successfully without Error.
The final dependencies in the build.gradle file of the app.
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test.ext:junit:1.1.1'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
implementation 'androidx.cardview:cardview:1.0.0'
implementation 'com.google.android.material:material:1.2.0-alpha03'
implementation 'androidx.recyclerview:recyclerview:1.2.0-alpha01'
implementation 'com.google.firebase:firebase-auth:19.2.0'
implementation 'com.google.firebase:firebase-database:19.2.0'
implementation 'com.firebaseui:firebase-ui-database:6.2.0'

How to use support library graddle.app in Kotlin?

I want to make a To-Do app in Kotlin. I opened the Android Studio.
What is the reason for this difference?
Android Studio version: Android Studio 3.5
Build #AI-191.8026.42.35.5791312, built on August 9, 2019
JRE: 1.8.0_202-release-1483-b03 amd64
JVM: OpenJDK 64-Bit
Windows 10
My Gradle Scripts :
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'androidx.core:core-ktx:1.1.0'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test:runner:1.2.0'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
}
This is the script in the video I watch:
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
implementation 'com.android.support:appcompat-v7:27.1.1'
implementation 'com.android.support:constraint:constraintlayout:1.1.2'
implementation 'com.android.support:design:27.1.1'
implementation 'com.android.support:cardview-v7:27.1.1'
}

Quoted from official doc:
Note: With the release of Android 9.0 (API level 28) there is a new
version of the support library called AndroidX which is part of
Jetpack. The AndroidX library contains the existing support library
and also includes the latest Jetpack components.
You can continue to use the support library. Historical artifacts
(those versioned 27 and earlier, and packaged as android.support.*)
will remain available on Google Maven. However, all new library
development will occur in the AndroidX library.
We recommend using the AndroidX libraries in all new projects. You
should also consider migrating existing projects to AndroidX as well.

Kotlin and Android Jetpack support in Android platform apps

I want to create an application which use some of the framework APIs. I have set the android:sharedUserId="android.uid.system" in AndroidManifest.xml.
In order to avoid reflection, I have imported the framework.jar
The apk is platform signed and I successfully installed the app.
However when I launch the app it crashes. The exception is
java.lang.ClassNotFoundException. It is unable to find the MainActivity.
Another exception is java.lang.ClassNotFoundException: Didn't find class "androidx.appcompat.app.AppCompatActivity".
I wish to know whether the framework.jar supports Kotlin and Android Jetpack libraries.
Gradle dependency:
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
implementation 'androidx.appcompat:appcompat:1.1.0-beta01'
implementation 'androidx.core:core-ktx:1.2.0-alpha01'
implementation 'androidx.constraintlayout:constraintlayout:2.0.0-beta1'
implementation files('libs/framework.jar')
testImplementation 'junit:junit:4.13-beta-3'
androidTestImplementation 'androidx.test:runner:1.2.0'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

Add those two lines to your gradle.properties file:
android.useAndroidX=true
android.enableJetifier=true
Try to add / change below line to your app/build.gradle
// implementation "androidx.core:core:1.0.2"
// use below kotlin dependency
implementation "androidx.core:core-ktx:1.0.2"

dependencies error when add firebase libraries

When add firebase in
dependencies
implementation 'com.google.firebase:firebase-core:16.0.6'
Or
implementation 'com.google.firebase:firebase-ads:17.1.2'
Or
implementation 'com.google.android.gms:play-services-ads:17.1.1
It shows error under implementation 'com.android.support:appcompat-v7:28.0.0' that All com.android.support libraries must use the exact same version specification (mixing versions can lead to runtime crashes).
When I sync the app no error but when install the app it shows you app has been stopped (Crashing during run time).
When remove the firebase dependencies and run, my app it's working fine.
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:28.0.0'
implementation 'com.android.support:animated-vector-drawable:28.0.0'
implementation 'com.android.support:support-media-compat:28.0.0'
implementation 'com.android.support.constraint:constraint-layout:1.1.3'
implementation 'com.android.support:design:28.0.0'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test.espresso:espresso-
core:3.0.2'
implementation 'com.google.firebase:firebase-core:16.0.6'
implementation 'com.google.firebase:firebase-ads:17.1.2'
implementation 'com.google.android.gms:play-services-ads:17.1.1'
}
apply plugin: 'com.google.gms.google-services'

When you include dependencies, they too, will sometimes include dependencies of their own. Some of the firebase libraries happen to include support libraries at a lower version than 28. When you hover over the error message for appcompat-v7 it should tell you what library is lower than 28. You may have to click 'show more' on the error message. Once you figure out which one it is, include that exact same library but version 28. Resync your gradle and you're good to go. Also, you might have to do this multiple times because some firebase libraries include multiple lower version support libraries and the error message will only show you one library at a time.