getting error as Caused by: java.lang.ClassCastException: androidx.viewpager2.widget.ViewPager2 cannot be cast to androidx.viewpager.widget.ViewPager

Question

I was building a city guide app where i used viewpager2 for swiping of pages left and right. It was running with 0 error until I added the this code which is given below . And got a error saying java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sahiladhav.cityguide/com.sahiladhav.cityguide.Common.OnBoarding}: java.lang.ClassCastException: androidx.viewpager2.widget.ViewPager2 cannot be cast to androidx.viewpager.widget.ViewPager.
What should I do??

 <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Common.OnBoarding"
    android:padding="20dp">


    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/slider"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toTopOf="@+id/relativelayout"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent ">

    </androidx.viewpager2.widget.ViewPager2>

    <RelativeLayout
        android:id="@+id/relativelayout"
        android:layout_width="match_parent"
        android:layout_height="150dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

            <Button
                android:id="@+id/get_started_btn"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="@string/let_get_started"
                android:background="@color/colorPrimary"/>

            <LinearLayout
                android:id="@+id/dots"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentBottom="true"
                android:padding="20dp"
                android:orientation="horizontal" />
        
            <Button
                android:id="@+id/next_btn"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentBottom="true"
                android:layout_alignParentRight="true"
                android:paddingBottom="20dp"
                android:background="#00000000"
                android:drawableEnd="@drawable/next_btn"
                android:drawableRight="@drawable/next_btn" />
        


    </RelativeLayout>





</androidx.constraintlayout.widget.ConstraintLayout>

MY JAVA CODE

package com.sahiladhav.cityguide.Common;

import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;
import androidx.viewpager2.widget.ViewPager2;

import android.os.Bundle;
import android.text.Html;
import android.transition.Slide;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.sahiladhav.cityguide.HelperClasses.SliderAdapter;
import com.sahiladhav.cityguide.R;

public class OnBoarding extends AppCompatActivity {

    ViewPager viewPager;
    LinearLayout dotsLayout;

    SliderAdapter sliderAdapter;
    TextView[] dots;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_on_boarding);

        //Hooks
        viewPager = findViewById(R.id.slider);
        dotsLayout = findViewById(R.id.dots);

        //Call adapter
        sliderAdapter = new SliderAdapter(this);
        viewPager.setAdapter(sliderAdapter);
        addDots();

    }

    private void addDots(){

        dots = new TextView[4];
        for (int i=0; i<dots.length; i++){
            dots[i] = new TextView(this);
            dots[i].setText(Html.fromHtml("&#8226;"));
            dots[i].setTextSize(35);

            dotsLayout.addView(dots[i]);
        }



    }
}

LOGS I AM GETTING , HOW CAN I SOLVE THIS ERROR , I CANT MOVE CODE FURTHER BEFORE SOLVING THIS..SOMEONE HELP ME PLEASE :((

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.sahiladhav.cityguide, PID: 10535
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sahiladhav.cityguide/com.sahiladhav.cityguide.Common.OnBoarding}: java.lang.ClassCastException: androidx.viewpager2.widget.ViewPager2 cannot be cast to androidx.viewpager.widget.ViewPager
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
     Caused by: java.lang.ClassCastException: androidx.viewpager2.widget.ViewPager2 cannot be cast to androidx.viewpager.widget.ViewPager
        at com.sahiladhav.cityguide.Common.OnBoarding.onCreate(OnBoarding.java:30)
        at android.app.Activity.performCreate(Activity.java:8000)
        at android.app.Activity.performCreate(Activity.java:7984)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:223) 
        at android.app.ActivityThread.main(ActivityThread.java:7656) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) 

Answer 1

you are using Viewpager2 in xml and imported and declared Viewpager in activty(which is wrong)

public class OnBoarding extends AppCompatActivity {

ViewPager2 viewPager; //change here
LinearLayout dotsLayou

Answer 2

只需将 viewpager2 从 xml 更改为 viewpager。