<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <!--Widget for exoplayer view-->
    <com.google.android.exoplayer2.ui.SimpleExoPlayerView
        android:id="@+id/idExoPlayerVIew"
        android:layout_width="match_parent"
        android:layout_height="500dp" />

</RelativeLayout>

import android.net.Uri;
import android.os.Bundle;
import android.util.Log;

import androidx.appcompat.app.AppCompatActivity;

import com.google.android.exoplayer2.ExoPlayerFactory;
import com.google.android.exoplayer2.SimpleExoPlayer;
import com.google.android.exoplayer2.extractor.DefaultExtractorsFactory;
import com.google.android.exoplayer2.extractor.ExtractorsFactory;
import com.google.android.exoplayer2.source.ExtractorMediaSource;
import com.google.android.exoplayer2.source.MediaSource;
import com.google.android.exoplayer2.trackselection.AdaptiveTrackSelection;
import com.google.android.exoplayer2.trackselection.DefaultTrackSelector;
import com.google.android.exoplayer2.trackselection.TrackSelector;
import com.google.android.exoplayer2.ui.SimpleExoPlayerView;
import com.google.android.exoplayer2.upstream.BandwidthMeter;
import com.google.android.exoplayer2.upstream.DefaultBandwidthMeter;
import com.google.android.exoplayer2.upstream.DefaultHttpDataSourceFactory;

public class MainActivity extends AppCompatActivity {

    // creating a variable for exoplayerview.
    SimpleExoPlayerView exoPlayerView;

    // creating a variable for exoplayer
    SimpleExoPlayer exoPlayer;

    // url of video which we are loading.
    String videoURL = "https://media.geeksforgeeks.org/wp-content/uploads/20201217163353/Screenrecorder-2020-12-17-16-32-03-350.mp4";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        exoPlayerView = findViewById(R.id.idExoPlayerVIew);
        try {

            // bandwisthmeter is used for 
            // getting default bandwidth
            BandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();

            // track selector is used to navigate between 
            // video using a default seekbar.
            TrackSelector trackSelector = new DefaultTrackSelector(new AdaptiveTrackSelection.Factory(bandwidthMeter));

            // we are adding our track selector to exoplayer.
            exoPlayer = ExoPlayerFactory.newSimpleInstance(this, trackSelector);

            // we are parsing a video url
            // and parsing its video uri.
            Uri videouri = Uri.parse(videoURL);

            // we are creating a variable for datasource factory
            // and setting its user agent as 'exoplayer_view'
            DefaultHttpDataSourceFactory dataSourceFactory = new DefaultHttpDataSourceFactory("exoplayer_video");

            // we are creating a variable for extractor factory
            // and setting it to default extractor factory.
            ExtractorsFactory extractorsFactory = new DefaultExtractorsFactory();

            // we are creating a media source with above variables 
            // and passing our event handler as null,
            MediaSource mediaSource = new ExtractorMediaSource(videouri, dataSourceFactory, extractorsFactory, null, null);

            // inside our exoplayer view 
            // we are setting our player
            exoPlayerView.setPlayer(exoPlayer);

            // we are preparing our exoplayer
            // with media source.
            exoPlayer.prepare(mediaSource);

            // we are setting our exoplayer
            // when it is ready.
            exoPlayer.setPlayWhenReady(true);

        } catch (Exception e) {
            // below line is used for 
            // handling our errors.
            Log.e("TAG", "Error : " + e.toString());
        }
    }
}