How to Build a TODO Android Application with AWS DynamoDB as Database?

package com.example.shreyaawsapp;

import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import com.amplifyframework.AmplifyException;
import com.amplifyframework.api.aws.AWSApiPlugin;
import com.amplifyframework.api.graphql.model.ModelQuery;
import com.amplifyframework.core.Amplify;
import com.amplifyframework.datastore.generated.model.Todo;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    
      // declaration
    public FloatingActionButton btn;
    public ListView lv;
    public String[] st;
    int i = 0;
    Handler handler;
    
      // the array adapter converts an ArrayList of objects
    // into View items filled into the ListView container
    ArrayAdapter<String> arrayAdapter;
    
      // list to store data
    public static List<String> ls;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
          // provide id to the layout items
        btn = findViewById(R.id.fab);
        st = new String[100];

        lv = findViewById(R.id.lt);
        
          // set listener to the floating button which takes
        // you to the next activity where you add and sore
        // your data
        btn.setOnClickListener(new View.OnClickListener() {
            @Override public void onClick(View v)
            {
                Intent intent = new Intent(MainActivity.this, MainActivity2.class);
                startActivity(intent);
            }
        });
        ls = new ArrayList<String>();
       
          // add the code below to initialize Amplpify
        try {
            // Add these lines to add the AWSApiPlugin plugins
            Amplify.addPlugin(new AWSApiPlugin());
            Amplify.configure(getApplicationContext());
            Log.i("MyAmplifyApp", "Initialized Amplify");
        }
        catch (AmplifyException error) {
            Log.e("MyAmplifyApp", "Could not initialize Amplify", error);
        }
       
          // add the code below to fetch 
          // data/run queries to
        // retrieve the stored data
        Amplify.API.query(ModelQuery.list(Todo.class), response -> {
                for (Todo todo : response.getData()) {
                    ls.add(todo.getName());
                    Log.i("MyAmplifyApp", todo.getName());
                }
            },
            error -> Log.e("MyAmplifyApp", "Query failure", error));
      
        handler = new Handler();
        final Runnable r = new Runnable() {
            public void run()
            {
                handler.postDelayed(this, 2000);
                arrayAdapter = new ArrayAdapter<String>(
                    getApplicationContext(),
                    android.R.layout.simple_list_item_1,
                    ls);
                lv.setAdapter(arrayAdapter);
                arrayAdapter.notifyDataSetChanged();
            }
        };
        handler.postDelayed(r, 1000);
    }
}

package com.example.shreyaawsapp;

import android.content.Intent;
import android.net.wifi.p2p.WifiP2pManager;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import com.amplifyframework.AmplifyException;
import com.amplifyframework.api.aws.AWSApiPlugin;
import com.amplifyframework.api.graphql.model.ModelMutation;
import com.amplifyframework.api.graphql.model.ModelQuery;
import com.amplifyframework.core.Amplify;
import com.amplifyframework.datastore.generated.model.Todo;
import java.util.ArrayList;
import java.util.List;

public class MainActivity2 extends AppCompatActivity {
  
    // declaration
    public EditText name, desc;
    public Button btn;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        // give id to the items
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        name = findViewById(R.id.edname);
        desc = findViewById(R.id.eddes);
        btn = findViewById(R.id.button2);
      
        // add the code below to initialize Amplify
        try {
            // Add these lines to add the AWSApiPlugin plugins
            Amplify.addPlugin(new AWSApiPlugin());
            Amplify.configure(getApplicationContext());
            Log.i("MyAmplifyApp", "Initialized Amplify");
        }
        catch (AmplifyException error) {
            Log.e("MyAmplifyApp", "Could not initialize Amplify", error);
        }
        // set listener on the store data button to store
        // data in dynamoDB
        btn.setOnClickListener(new View.OnClickListener() {
            @Override public void onClick(View v)
            {
                String name1 = name.getText().toString();
                String name2 = desc.getText().toString();
                // add the code below to create a todo item
                // with two properties a name and a
                // description
                Todo todo = Todo.builder()
                                .name(name1)
                                .description(name2)
                                .build();
                // add the code below  to save item using mutate
                Amplify.API.mutate(ModelMutation.create(todo), response -> Log.i(
                        "MyAmplifyApp", "Added Todo with id: " + response.getData().getId()),
                    error
                    -> Log.e("MyAmplifyApp", "Create failed", error));
            }
        });
    }
    // move to the next activity
    @Override public void onBackPressed()
    {
        super.onBackPressed();
        startActivity(new Intent(MainActivity2.this, MainActivity.class));
    }
}