ClassNotFoundException re android.support.v4.view.ViewPager when inflating

Question

I am adding a ViewPager to my app in Android Studio but when I try to run it, it's throwing a ClassNotFoundException re class "android.support.v4.view.ViewPager".

Have done lots of googling and tried changing the dependencies in build.gradle, but nothing has changed the error I'm seeing.

Here are the relevant error lines from Logcat:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.playmusic/com.example.android.playmusic.MainActivity}: android.view.InflateException: Binary XML file line #60: Binary XML file line #60: Error inflating class android.support.v4.view.ViewPager
...
Caused by: android.view.InflateException: Binary XML file line #60: Binary XML file line #60: Error inflating class android.support.v4.view.ViewPager
Caused by: android.view.InflateException: Binary XML file line #60: Error inflating class android.support.v4.view.ViewPager
Caused by: java.lang.ClassNotFoundException: Didn't find class "android.support.v4.view.ViewPager" on path: DexPathList[[zip file "/data/app/com.example.android.playmusic--Sh7PlYKQR0g2meRQdvXcg==/base.apk"],nativeLibraryDirectories=[/data/app/com.example.android.playmusic--Sh7PlYKQR0g2meRQdvXcg==/lib/arm64, /system/lib64, /system/vendor/lib64]]

Here is the main_activity.xml layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/my_toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        android:elevation="4dp"
        android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/>

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/main_tabs"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        app:tabMode="scrollable">

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/tab0" />

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/tab1" />

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/tab2" />

    </com.google.android.material.tabs.TabLayout>

    <!-- View pager to swipe views -->
    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="fill_parent"/>

</LinearLayout>

Here are my dependencies in build.gradle. As you can see I have tried using both androidx and com.android.support versions of viewpager artefact:

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation "com.android.support:design: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'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'androidx.recyclerview:recyclerview:1.0.0'
    implementation 'com.loopj.android:android-async-http:1.4.9'
    implementation "android.arch.lifecycle:extensions:1.1.0"
    implementation "android.arch.lifecycle:viewmodel:1.1.0"
    //implementation "androidx.viewpager:viewpager:1.0.0"
    implementation "com.android.support:viewpager:28.0.0"
}

Any help would be really welcome :)

Answer 1

If you are using implementation "androidx.viewpager:viewpager:1.0.0"

Also, change in XML file too

<androidx.viewpager.widget.ViewPager
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="fill_parent"/>

Answer 2

For androidX support library for viewpager has been replaced with

androidx.viewpager:viewpager:1.0.0

Replace your dependency with this in your gradle.

You are mixing libraries for androidX and support library, Use either one of them. Update non-androidX dependency with androidX one or replace androidX with support libraries.