videoview.setVideoUri shows null pointer exception

You should add a contentView on your activity onCreate So change your onCreate Like this:

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.your_layout_name)  // Add this line, 
        VideoView videoView=findViewById(R.id.videoView);
        String path="android.resource://"+getPackageName()+"/"+R.raw.playthis;
        Uri uri=Uri.parse(path);
        videoView.setVideoPath(uri.getPath());
    }

After that you should check null video path, like

// If path is not null then set it to your videoView.
if(uri.getPath() != null) {
    videoView.setVideoPath(uri.getPath());
}