why i got runtime exception while using Recycler View in android

Question

I am learning Recycler view and just build the basic list to display name and number but got the runtime exception

Here is the code

MainActivity.java

package com.example.listviewandrecyclerview;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private List< Person> personData;
    private RecyclerView recyclerView;
    private RecyclerViewAdapter recyclerViewAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        recyclerView = (RecyclerView) findViewById(R.id.recyclerView);

        personData = new ArrayList();
        personData.add( new Person("Hemant","1"));
        personData.add( new Person("Prashant","144"));
        personData.add( new Person("sagar","331"));
        personData.add( new Person("mayank","31"));
        personData.add( new Person("mayur","13"));
        personData.add( new Person("Hemant","1"));
        personData.add( new Person("Prashant","144"));
        personData.add( new Person("sagar","331"));
        personData.add( new Person("mayank","31"));
        personData.add( new Person("mayur","13"));

        recyclerViewAdapter = new RecyclerViewAdapter(personData, this);

        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);

        recyclerView.setLayoutManager(linearLayoutManager);
        recyclerView.setAdapter(recyclerViewAdapter);

    }
}

RecyclerViewAdpater.java

package com.example.listviewandrecyclerview;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.Holder> {

    private List<Person> personList;
    private Context context;

    public RecyclerViewAdapter(List<Person> list, Context context) {
        this.personList = list;
        this.context = context;
    }


    @NonNull
    @Override
    public Holder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.recycler_layout, parent, false);
        return new Holder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull Holder holder, int position) {

        Person currPerson = personList.get(position);

        holder.textViewName.setText(currPerson.getName());
        holder.textViewNumber.setText(currPerson.getNumber());

    }

    @Override
    public int getItemCount() {
        return personList.size();
    }


    class Holder extends RecyclerView.ViewHolder {

        public TextView textViewName;
        public TextView textViewNumber;

        public Holder(@NonNull View itemView) {
            super(itemView);
            textViewName = (TextView) itemView.findViewById(R.id.name);
            textViewNumber = (TextView) itemView.findViewById(R.id.number);
        }
    }

}

Person.java

package com.example.listviewandrecyclerview;

public class Person  {
    public String Name, Number;

    public Person(String name, String number) {
        this.Name = name;
        this.Number = number;
    }

    public String getName() {
        return Name;
    }

    public String getNumber() {
        return Number;
    }

}

activity_main.xml

<?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=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="0dp"
        android:layout_height="729dp"
        android:layout_marginStart="1dp"
        android:layout_marginLeft="1dp"
        android:layout_marginEnd="1dp"
        android:layout_marginRight="1dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

recycler_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="5dp" >

    <androidx.constraintlayout.widget.ConstraintLayout

        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:id="@+id/name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TextView"
            android:textSize="36sp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <TextView
            android:id="@+id/number"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TextView"
            android:textSize="36sp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="@+id/name" />

    </androidx.constraintlayout.widget.ConstraintLayout>

</androidx.cardview.widget.CardView>

But i got excpeton like this E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.listviewandrecyclerview, PID: 8041 android.view.InflateException: Binary XML file line #2: Binary XML file line #2: Error inflating class androidx.cardview.widget.CardView Caused by: android.view.InflateException: Binary XML file line #2: Error inflating class androidx.cardview.widget.CardView Caused by: java.lang.ClassNotFoundException: Didn't find class "androidx.cardview.widget.CardView" on path: DexPathList[[zip file "/data/app/com.example.listviewandrecyclerview-r3wz8HXjSJP_-5GXxapOHA==/base.apk"],nativeLibraryDirectories=[/data/app/com.example.listviewandrecyclerview-r3wz8HXjSJP_-5GXxapOHA==/lib/x86, /system/lib]] at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:134) at java.lang.ClassLoader.loadClass(ClassLoader.java:379) at java.lang.ClassLoader.loadClass(ClassLoader.java:312) at android.view.LayoutInflater.createView(LayoutInflater.java:606) at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:790) at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730) at android.view.LayoutInflater.inflate(LayoutInflater.java:492) at android.view.LayoutInflater.inflate(LayoutInflater.java:423) at com.example.listviewandrecyclerview.RecyclerViewAdapter.onCreateViewHolder(RecyclerViewAdapter.java:28) at com.example.listviewandrecyclerview.RecyclerViewAdapter.onCreateViewHolder(RecyclerViewAdapter.java:14)

Answer 1

I've tried your code and I got the solution as mentioned in the screenshot

Go with the following solutions:

• Please try to do Invalidate cache and restart

• Also, check you've added appcompat, constraint layout, and material dependencies

implementation 'androidx.appcompat:appcompat:1.2.0'

implementation 'androidx.constraintlayout:constraintlayout:2.0.1'

implementation 'com.google.android.material:material:1.2.1'

• Make sure you have updated SDK