java.lang.ClassCastException: UserViewHolder cannot be cast to BotViewHolder

Question

i'm trying to implement brainshop AI API into my android studio application to output response from the chatbot to the user's input or question but i am getting this java.lang.ClassCastException.

ERROR java.lang.ClassCastException: com.android.smartpoly.MessageRVAdapter$UserViewHolder cannot be cast to com.android.smartpoly.MessageRVAdapter$BotViewHolder

MainActivity.java

package com.android.smartpoly;

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

import java.io.*;
import java.util.ArrayList;

import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.TextView;
import android.widget.Toast;

import com.android.volley.RequestQueue;
import com.android.volley.toolbox.Volley;


import com.google.android.material.bottomnavigation.BottomNavigationView;
import com.google.android.material.navigation.NavigationBarView;
import com.google.firebase.auth.FirebaseAuth;

import okhttp3.Request;
import okio.Timeout;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class MainActivity extends AppCompatActivity {
    FirebaseAuth auth;
    TextView usernameTxt;
    Button signOutbtn;
    private RecyclerView chatsRV;
    private ImageButton sendMsgIB;
    private EditText userMsgEdt;
    private final String USER_KEY = "user";
    private final String BOT_KEY = "bot";

    // creating a variable for
    // our volley request queue.
    private RequestQueue mRequestQueue;

    // creating a variable for array list and adapter class.
    private ArrayList<ChatModal> chatModalArrayList;
    private MessageRVAdapter messageRVAdapter;

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

        BottomNavigationView bottomNav = (BottomNavigationView) findViewById(R.id.bottom_nav);
        // Set Selected Id
        bottomNav.setSelectedItemId(R.id.chatbot);
        Menu menu=bottomNav.getMenu();
        auth=FirebaseAuth.getInstance();
        signOutbtn=(Button)findViewById(R.id.signOut);
        usernameTxt=(TextView)findViewById(R.id.username);

        // on below line we are initializing all our views.
        chatsRV = findViewById(R.id.idRVChats);
        sendMsgIB = findViewById(R.id.idIBSend);
        userMsgEdt = findViewById(R.id.idEdtMessage);

        // below line is to initialize our request queue.
        mRequestQueue = Volley.newRequestQueue(MainActivity.this);
        mRequestQueue.getCache().clear();

        // creating a new array list
        chatModalArrayList = new ArrayList<>();

        if (auth!=null)
        {
            String currentUser=auth.getCurrentUser().getEmail();
            usernameTxt.setText(currentUser);
            logout();
        }

        // on below line we are initializing our adapter class and passing our array list to it.
        messageRVAdapter = new MessageRVAdapter(chatModalArrayList, this);

        // below line we are creating a variable for our linear layout manager.
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(MainActivity.this);

        // below line is to set layout
        // manager to our recycler view.
        chatsRV.setLayoutManager(linearLayoutManager);

        // below line we are setting
        // adapter to our recycler view.
        chatsRV.setAdapter(messageRVAdapter);

        // adding on click listener for send message button.
        sendMsgIB.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // checking if the message entered
                // by user is empty or not.
                if (userMsgEdt.getText().toString().isEmpty()) {
                    // if the edit text is empty display a toast message.
                    Toast.makeText(MainActivity.this, "Please enter your message..", Toast.LENGTH_SHORT).show();
                    return;
                }

                // calling a method to send message
                // to our bot to get response.
                getResponse(userMsgEdt.getText().toString());

                // below line we are setting text in our edit text as empty
                userMsgEdt.setText("");
            }
        });


        bottomNav.setOnItemSelectedListener(new NavigationBarView.OnItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                int id = item.getItemId();
                switch (id) {
                    case R.id.introduction:
                        Intent intro = new Intent(MainActivity.this, Intro.class);
                        startActivity(intro);
                        break;

                    case R.id.activity:
                        Intent activity = new Intent(MainActivity.this, Activities.class);
                        startActivity(activity);
                        break;

                    case R.id.chatbot:
                        break;

                    case R.id.staff:
                        Intent staff = new Intent(MainActivity.this, Staff.class);
                        startActivity(staff);
                        break;

                    case R.id.aboutus:
                        Intent aboutus = new Intent(MainActivity.this, AboutUs.class);
                        startActivity(aboutus);
                        break;
                }
                return true;
            }
        });

    }
    private void logout()
    {
        signOutbtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                auth.signOut();
                startActivity(new Intent(MainActivity.this, AuthActivity.class));

                finish();
            }
        });
    }

    private void getResponse (String message) {
        chatModalArrayList.add(new ChatModal(message, USER_KEY));
        messageRVAdapter.notifyDataSetChanged();
        String url= "http://api.brainshop.ai/get?bid=174120&key=KwxcDibecKUNMRyr&uid=[uid]&msg=[msg]";
        String BASE_URL="http://api.brainshop.ai/";
        Retrofit retrofit=new Retrofit.Builder()
                .baseUrl(BASE_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .build();
        RetroAPI retrofitAPI=retrofit.create(RetroAPI.class);
        Call<MsgModal> call=retrofitAPI.getMessage(url);
        call.enqueue(new Callback<MsgModal>() {
            @Override
            public void onResponse(Call<MsgModal> call, Response<MsgModal> response) {
                if(response.isSuccessful()) {
                    MsgModal modal=response.body();
                    chatModalArrayList.add(new ChatModal(modal.getCnt(), BOT_KEY));
                    messageRVAdapter.notifyDataSetChanged();
                }
            }

            @Override
            public void onFailure(Call<MsgModal> call, Throwable t) {
                chatModalArrayList.add(new ChatModal("Please revert your question", BOT_KEY));
                messageRVAdapter.notifyDataSetChanged();
            }
        });
    }
}

MessageRVAdapter.java

package com.android.smartpoly;

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.ArrayList;

public class MessageRVAdapter extends RecyclerView.Adapter {
    private ArrayList<ChatModal> chatsModalArrayList;
    private Context context;

    public MessageRVAdapter(ArrayList<ChatModal> chatsModalArrayList, Context context) {
        this.chatsModalArrayList = chatsModalArrayList;
        this.context = context;
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view;
        switch (viewType) {
            case 0:
                view=LayoutInflater.from(parent.getContext()).inflate(R.layout.user_msg, parent, false);
                return new UserViewHolder(view);
            case 1 :
                view=LayoutInflater.from(parent.getContext()).inflate(R.layout.bot_msg, parent, false);
                return new BotViewHolder(view);
        }
        return null;
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
        ChatModal chatsModal=chatsModalArrayList.get(position);
        switch (chatsModal.getSender()) {
            case "user":
                ((UserViewHolder)holder).userTV.setText(chatsModal.getMessage());
                break;
            case "bot" :
                ((BotViewHolder)holder).botMsgTV.setText(chatsModal.getMessage());
                break;
        }
    }

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

    public static class UserViewHolder extends RecyclerView.ViewHolder {
        TextView userTV;
        public UserViewHolder(@NonNull View itemView) {
            super(itemView);
            userTV=itemView.findViewById(R.id.TVUser);
        }
    }

    public static class BotViewHolder extends RecyclerView.ViewHolder {
        TextView botMsgTV;
        public BotViewHolder(@NonNull View itemView) {
            super(itemView);
            botMsgTV=itemView.findViewById(R.id.TVBot);
        }
    }
}

MsgModal.java

package com.android.smartpoly;

public class MsgModal {
    private String cnt;

    public String getCnt() {
        return cnt;
    }

    public void setCnt(String cnt) {
        this.cnt=cnt;
    }

    public MsgModal(String cnt) {
        this.cnt=cnt;
    }
}

ChatModal.java

package com.android.smartpoly;

public class ChatModal {

    // string to store our message and sender
    private String message;
    private String sender;

    // constructor.
    public ChatModal(String message, String sender) {
        this.message = message;
        this.sender = sender;
    }

    // getter and setter methods.
    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public String getSender() {
        return sender;
    }

    public void setSender(String sender) {
        this.sender = sender;
    }
}

I am new to programming and hoping someone can help me fix it

Answer 1

You need to override getItemViewType() method in your adapter. Also you can check here

    @Override
    public int getItemViewType(int position) {
        ChatModal item = chatsModalArrayList.get(position);
        if(item.getSender().equals("user")){
            return 0;
        }
        else {
            return 1;
        }
    }