In order to get started you need to install the volley library inside your android project like this

colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="colorPrimary">#42C14B</color>
    <color name="colorPrimaryDark">#3BC545</color>
    <color name="colorAccent">#05af9b</color>

    <color name="color_one">#fb7268</color>
    <color name="color_white">#ededf2</color>

</resources>

build.gradle

// Volley library
implementation 'com.android.volley:volley:1.1.1'

And also we need to add the internet permission to get data from the api

<!--Allow Internet Permission-->
<uses-permission android:name="android.permission.INTERNET" />

XML Code

<?xml version="1.0" encoding="utf-8"?>
<ScrollView
    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"
    android:background="@color/color_white"
    android:orientation="vertical"
    tools:context=".MainActivity">


    <!--Linear Layout to display all the details-->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="20dp"
        android:orientation="vertical">

        <!--Text view to display Global stats-->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Global Stats"
            android:textColor="#050505"
            android:textAllCaps="true"
            android:textAlignment="center"
            android:textSize="35sp"
            android:textStyle="bold"/>

            <!--Text view to display Total Cases-->
            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:fontFamily="sans-serif-light"
                android:layout_marginTop="20dp"
                android:text="Total Cases"
                android:textAlignment="center"
                android:textStyle="bold"
                android:textSize="30sp"/>

            <!--Text view to display the updated number when data
            will fetch from the API. For now default set to 0 -->
            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="0"
                android:id="@+id/tvCases"
                android:textAlignment="center"
                android:textSize="25sp"
                android:textColor="@color/color_one"
                android:textStyle="bold"
                android:fontFamily="sans-serif-light" />

        <!--Text view to display Recovered Cases-->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fontFamily="sans-serif-light"
            android:text="Recovered"
            android:textAlignment="center"
            android:textStyle="bold"
            android:textSize="30sp"/>

        <!--Text view to display the updated number when data
        will fetch from the API. For now default set to 0 -->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="0"
            android:id="@+id/tvRecovered"
            android:textAlignment="center"
            android:textSize="25sp"
            android:textColor="@color/color_one"
            android:textStyle="bold"
            android:fontFamily="sans-serif-light" />

        <!--Text view to display Critical Cases-->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fontFamily="sans-serif-light"
            android:text="Critical"
            android:textAlignment="center"
            android:textStyle="bold"
            android:textSize="30sp"/>

        <!--Text view to display the updated number when data
        will fetch from the API. For now default set to 0 -->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="0"
            android:id="@+id/tvCritical"
            android:textAlignment="center"
            android:textSize="25sp"
            android:textColor="@color/color_one"
            android:textStyle="bold"
            android:fontFamily="sans-serif-light" />

        <!--Text view to display Active Cases-->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fontFamily="sans-serif-light"
            android:text="Active"
            android:textAlignment="center"
            android:textStyle="bold"
            android:textSize="30sp"/>

        <!--Text view to display the updated number when data
        will fetch from the API. For now default set to 0 -->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="0"
            android:id="@+id/tvActive"
            android:textAlignment="center"
            android:textSize="25sp"
            android:textColor="@color/color_one"
            android:textStyle="bold"
            android:fontFamily="sans-serif-light" />

        <!--Text view to display Today Cases-->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fontFamily="sans-serif-light"
            android:text="Today Cases"
            android:textAlignment="center"
            android:textStyle="bold"
            android:textSize="30sp"/>

        <!--Text view to display the updated number when data
        will fetch from the API. For now default set to 0 -->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="0"
            android:id="@+id/tvTodayCases"
            android:textAlignment="center"
            android:textSize="25sp"
            android:textColor="@color/color_one"
            android:textStyle="bold"
            android:fontFamily="sans-serif-light" />

        <!--Text view to display Total Deaths-->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fontFamily="sans-serif-light"
            android:text="Total Deaths"
            android:textAlignment="center"
            android:textStyle="bold"
            android:textSize="30sp"/>

        <!--Text view to display the updated number when data
        will fetch from the API. For now default set to 0 -->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="0"
            android:id="@+id/tvTotalDeaths"
            android:textAlignment="center"
            android:textSize="25sp"
            android:textColor="@color/color_one"
            android:textStyle="bold"
            android:fontFamily="sans-serif-light" />

        <!--Text view to display Today Deaths-->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fontFamily="sans-serif-light"
            android:text="Today Deaths"
            android:textAlignment="center"
            android:textStyle="bold"
            android:textSize="30sp"/>

        <!--Text view to display the updated number when data
        will fetch from the API. For now default set to 0 -->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="0"
            android:id="@+id/tvTodayDeaths"
            android:textAlignment="center"
            android:textSize="25sp"
            android:textColor="@color/color_one"
            android:textStyle="bold"
            android:fontFamily="sans-serif-light" />

        <!--Text view to display Affected Countries-->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fontFamily="sans-serif-light"
            android:text="Affected Countries"
            android:textAlignment="center"
            android:textStyle="bold"
            android:textSize="30sp"/>

        <!--Text view to display the updated number when data
        will fetch from the API. For now default set to 0 -->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="0"
            android:id="@+id/tvAffectedCountries"
            android:textAlignment="center"
            android:textSize="25sp"
            android:textColor="@color/color_one"
            android:textStyle="bold"
            android:fontFamily="sans-serif-light" />

        </LinearLayout>

</ScrollView>

Java Code

package com.example.covid_19tracker;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;

import org.json.JSONException;
import org.json.JSONObject;

public class MainActivity
    extends AppCompatActivity {

    // Create the object of TextView
    TextView tvCases, tvRecovered,
        tvCritical, tvActive,
        tvTodayCases, tvTotalDeaths,
        tvTodayDeaths,
        tvAffectedCountries;

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

        // Link those objects with their respective id's
        // that we have given in .XML file
        tvCases
            = findViewById(R.id.tvCases);
        tvRecovered
            = findViewById(R.id.tvRecovered);
        tvCritical
            = findViewById(R.id.tvCritical);
        tvActive
            = findViewById(R.id.tvActive);
        tvTodayCases
            = findViewById(R.id.tvTodayCases);
        tvTotalDeaths
            = findViewById(R.id.tvTotalDeaths);
        tvTodayDeaths
            = findViewById(R.id.tvTodayDeaths);
        tvAffectedCountries
            = findViewById(R.id.tvAffectedCountries);

        // Creating a method fetchdata()
        fetchdata();
    }

    private void fetchdata()
    {

        // Create a String request
        // using Volley Library
        String url = "https:// corona.lmao.ninja/v2/all";

        StringRequest request
            = new StringRequest(
                Request.Method.GET,
                url,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response)
                    {

                        // Handle the JSON object and
                        // handle it inside try and catch
                        try {

                            // Creating object of JSONObject
                            JSONObject jsonObject
                                = new JSONObject(
                                    response.toString());

                            // Set the data in text view
                            // which are available in JSON format
                            // Note that the parameter inside
                            // the getString() must match
                            // with the name given in JSON format
                            tvCases.setText(
                                jsonObject.getString(
                                    "cases"));
                            tvRecovered.setText(
                                jsonObject.getString(
                                    "recovered"));
                            tvCritical.setText(
                                jsonObject.getString(
                                    "critical"));
                            tvActive.setText(
                                jsonObject.getString(
                                    "active"));
                            tvTodayCases.setText(
                                jsonObject.getString(
                                    "todayCases"));
                            tvTotalDeaths.setText(
                                jsonObject.getString(
                                    "deaths"));
                            tvTodayDeaths.setText(
                                jsonObject.getString(
                                    "todayDeaths"));
                            tvAffectedCountries.setText(
                                jsonObject.getString(
                                    "affectedCountries"));
                        }
                        catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error)
                    {
                        Toast.makeText(
                                MainActivity.this,
                                error.getMessage(),
                                Toast.LENGTH_SHORT)
                            .show();
                    }
                });

        RequestQueue requestQueue
            = Volley.newRequestQueue(this);
        requestQueue.add(request);
    }
}