Spotify Android - Make Authorized Web Requests

I'm working on an Android app that implements the Spotify API to allow the users to listen to music. I've configured the Player that Spotify has created for android devices, but it's incredibly limited in terms of its functionality, so I've had to go through Spotify's Web API to do more advanced features.

I've hit a bug when trying to get a list of the user's own playlists. I'm making a request using:

URL url = new URL("http://ift.tt/2oU446N");
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

But instead of this command going through like it does for the other web API requests I've made, it throws the error:

 java.io.FileNotFoundException: http://ift.tt/2oU446N
                                                                               at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:242)
                                                                               at com.android.okhttp.internal.huc.DelegatingHttpsURLConnection.getInputStream(DelegatingHttpsURLConnection.java:210)
                                                                               at com.android.okhttp.internal.huc.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:25)
                                                                               at com.tmacstudios.spotifyvoice.WebWrapper$override.searchUserPlaylist(WebWrapper.java:257)
                                                                               at com.tmacstudios.spotifyvoice.WebWrapper$override.access$dispatch(WebWrapper.java)
                                                                               at com.tmacstudios.spotifyvoice.WebWrapper.searchUserPlaylist(WebWrapper.java:0)
                                                                               at com.tmacstudios.spotifyvoice.MainActivity$6.run(MainActivity.java:382)
                                                                               at java.lang.Thread.run(Thread.java:818)

I'm not entirely sure why I'm getting this error, but I think it may have to do with not having the necessary authorization to make this request. Can anyone please help me solve this problem?