How to Create a Chatbot in Android with BrainShop API?

package org.geeksforgeeks.demo;

public class Model {
    private String message;
    private String sender;

    // Default Constructor (Required for Firebase)
    public Model() {
        this.message = "";
        this.sender = "";
    }

    // Parameterized Constructor
    public Model(String message, String sender) {
        this.message = message;
        this.sender = sender;
    }

    // Getter and Setter for message
    public String getMessage() {
        return message;
    }

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

    // Getter and Setter for sender
    public String getSender() {
        return sender;
    }

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

package org.geeksforgeeks.demo;

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 Adapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
    private final ArrayList<Model> list;

    // Constructor
    public Adapter(ArrayList<Model> list) {
        this.list = list;
    }

    @Override
    public int getItemViewType(int position) {
        // Determine the type of view
        if (list.get(position).getSender().equals("user")) {
            
            // User message
            return 0; 
        } 
        else if (list.get(position).getSender().equals("bot")) {
            
            // Bot message
            return 1; 
        } 
        else {
            return -1;
        }
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view;
        if (viewType == 0) {
            view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.item_user_messages, parent, false);
            return new UserViewHolder(view);
        } else {
            view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.item_bot_messages, parent, false);
            return new BotViewHolder(view);
        }
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
        Model model = list.get(position);

        if (holder instanceof UserViewHolder) {
            ((UserViewHolder) holder).userTV.setText(model.getMessage());
        } else if (holder instanceof BotViewHolder) {
            ((BotViewHolder) holder).botTV.setText(model.getMessage());
        }
    }

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

    // ViewHolder for User messages
    static class UserViewHolder extends RecyclerView.ViewHolder {
        TextView userTV;

        public UserViewHolder(@NonNull View itemView) {
            super(itemView);
            userTV = itemView.findViewById(R.id.idTVUser);
        }
    }

    // ViewHolder for Bot messages
    static class BotViewHolder extends RecyclerView.ViewHolder {
        TextView botTV;

        public BotViewHolder(@NonNull View itemView) {
            super(itemView);
            botTV = itemView.findViewById(R.id.idTVBot);
        }
    }
}

package org.geeksforgeeks.demo;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    private RecyclerView recyclerView;
    private FloatingActionButton button;
    private EditText editText;

    // Creating a variable for Volley request queue.
    private RequestQueue requestQueue;

    // Creating variables for the list and adapter.
    private ArrayList<Model> list;
    private Adapter adapter;

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

        recyclerView = findViewById(R.id.recyclerView);
        button = findViewById(R.id.sendButton);
        editText = findViewById(R.id.messageEditText);

        // Initializing the request queue.
        requestQueue = Volley.newRequestQueue(this);
        requestQueue.getCache().clear();

        // Creating a new array list.
        list = new ArrayList<>();

        // Adding click listener for send button.
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                
                // Checking if user entered a message.
                if (editText.getText().toString().isEmpty()) {
                    Toast.makeText(MainActivity.this, "Please enter your message..", Toast.LENGTH_SHORT).show();
                    return;
                }

                // Sending message to bot.
                sendMessage(editText.getText().toString());

                // Clearing edit text.
                editText.setText("");
            }
        });

        // Initializing adapter.
        adapter = new Adapter(list);

        // Setting up layout manager.
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this, RecyclerView.VERTICAL, false);
        recyclerView.setLayoutManager(linearLayoutManager);

        // Setting adapter to RecyclerView.
        recyclerView.setAdapter(adapter);
    }

    @SuppressLint("NotifyDataSetChanged")
    private void sendMessage(String userMsg) {
        
        // Adding user message to list.
        list.add(new Model(userMsg, USER_KEY));
        adapter.notifyDataSetChanged();

        // URL for API call.
        String url = "Enter your API URL here" + userMsg;

        // Creating request queue.
        RequestQueue queue = Volley.newRequestQueue(this);

        // Creating a JSON object request.
        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(
                Request.Method.GET, url, null,
                response -> {
                    try {
                        
                        // Extracting response from JSON.
                        String botResponse = response.getString("cnt");
                        list.add(new Model(botResponse, BOT_KEY));

                        // Notifying adapter.
                        adapter.notifyDataSetChanged();
                    } catch (JSONException e) {
                        e.printStackTrace();

                        // Handling error response from bot.
                        list.add(new Model("No response", BOT_KEY));
                        adapter.notifyDataSetChanged();
                    }
                },
                error -> {
                    
                    // Handling errors.
                    list.add(new Model("Sorry, no response found", BOT_KEY));
                    Toast.makeText(MainActivity.this, "No response from the bot..", Toast.LENGTH_SHORT).show();
                });

        // Adding request to queue.
        queue.add(jsonObjectRequest);
    }

    // Constants for user and bot.
    private static final String USER_KEY = "user";
    private static final String BOT_KEY = "bot";
}