Duplicate class android.support.v4.app.INotificationSideChannel found in modules classes?

Question

I am developing a news app but I am getting following errors in from gradle console

(androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.app.INotificationSideChannel$Stub found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.app.INotificationSideChannel$Stub$Proxy found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.graphics.drawable.IconCompatParcelizer found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.IResultReceiver found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.IResultReceiver$Stub found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.IResultReceiver$Stub$Proxy found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.ResultReceiver found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.ResultReceiver$1 found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.ResultReceiver$MyResultReceiver found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class android.support.v4.os.ResultReceiver$MyRunnable found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class androidx.core.graphics.drawable.IconCompatParcelizer found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class androidx.core.internal.package-info found in modules classes.jar (androidx.core:core:1.0.1) and classes.jar (com.android.support:support-compat:28.0.0)
Duplicate class androidx.versionedparcelable.CustomVersionedParcelable found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.NonParcelField found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.ParcelField found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.ParcelImpl found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.ParcelImpl$1 found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.ParcelUtils found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.VersionedParcel found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.VersionedParcel$1 found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.VersionedParcel$ParcelException found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.VersionedParcelParcel found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.VersionedParcelStream found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.VersionedParcelStream$FieldBuffer found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.VersionedParcelStream$InputBuffer found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.VersionedParcelable found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
Duplicate class androidx.versionedparcelable.VersionedParcelize found in modules class

below my app.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.myapplication"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    implementation 'com.github.bassaer:chatmessageview:2.0.1'
    implementation 'com.google.code.gson:gson:2.8.5'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

Answer 1

You can add below 2 lines into your gradle.properties file:

android.useAndroidX=true
android.enableJetifier=true

Note to check, to not repeat any line that already exists (and ensure existing are true).

---

Details:

If you want to use androidx-namespaced libraries in a new project, you need to set the compile SDK to Android 9.0 (API level 28) or higher and set both of the mentioned Android Gradle plugin flags to true.

android.useAndroidX: When this flag is set to true, the Android plugin uses the appropriate AndroidX library instead of a Support Library. The flag is false by default if it is not specified.

android.enableJetifier: When this flag is set to true, the Android plugin automatically migrates existing third-party libraries to use AndroidX dependencies by rewriting their binaries. The flag is false by default if it is not specified.