android - Get all videos of a YouTube Playlist in Java -

context i'm working android studio (java). want obtain videos of given playlist (or 50, other after).

problem see people using url https://www.googleapis.com/youtube/v3/playlistitems?part=snippet&maxresults=50&playlistid=pliewzfngb4fvrrztonlvemj6db2nmzg2m&key=aizasyc2_yrcte9916fsma0_krnef43gblzz8m0 don't know how implement in java. follow tuto , got way information totally different :

youtube.search.list query; query = youtube.search().list("id,snippet");       query.setkey(my_api_key);       query.setmaxresults((long)20);       query.settype("video");       query.setfields("items(id/videoid,snippet/title,snippet/description,snippet/thumbnails/default/url)"); 

and don't understand how else search. of documentation in english only...

edit ok, continued try, think got near solution, got error.

private youtube youtube; private youtube.playlistitems.list playlistitemrequest; private string playlist_id = "pliewzfngb4fvrrztonlvemj6db2nmzg2m"; public static final string key = "aizasyc2_yrcte9916fsma0_krnef43gblzz8m0";  // constructor public youtubeconnector(context context) {     youtube = new youtube.builder(new nethttptransport(),             new jacksonfactory(), new httprequestinitializer()     {         @override         public void initialize(httprequest hr) throws ioexception {}     }).setapplicationname(context.getstring(r.string.app_name)).build(); }  public list<videoitem> result() {     list<playlistitem> playlistitemlist = new arraylist<playlistitem>();     try     {     /* here must problem ! */         playlistitemrequest = youtube.playlistitems().list("snippet");         playlistitemrequest.setplaylistid(playlist_id);         playlistitemrequest.setfields("items(id/videoid,snippet/title,snippet/description,snippet/thumbnails/default/url),nextpagetoken,pageinfo");         playlistitemrequest.setkey(key);         string nexttoken = "";         {             playlistitemrequest.setpagetoken(nexttoken);             playlistitemlistresponse playlistitemresult = playlistitemrequest.execute();              playlistitemlist.addall(playlistitemresult.getitems());              nexttoken = playlistitemresult.getnextpagetoken();         } while (nexttoken != null);     }catch(ioexception e)     {         log.d("yc", "could not initialize: "+e);     } //[...] } 

here error got : { "code" : 400, "errors" : [ { "domain" : "global", "location" : "fields", "locationtype" : "parameter", "message" : "invalid field selection videoid", "reason" : "invalidparameter" } ], "message" : "invalid field selection videoid" }

edit 2 : martijn woudstra. correct line :

playlistitemrequest = youtube.playlistitems().list("snippet,contentdetails"); //[...] playlistitemrequest.setfields("items(snippet/title,snippet/description,snippet/thumbnails/default/url,contentdetails/videoid),nextpagetoken,pageinfo"); //[...] videoitem.setid(item.getcontentdetails().getvideoid()); 

i know old question important identify resources using understand how proper information. there many resources in youtube api v3, use search, video, playlist , playlistitems.

according documentation following json structure shows format of playlistitems resource:

{   "kind": "youtube#playlistitem",   "etag": etag,   "id": string,   "snippet": {     "publishedat": datetime,     "channelid": string,     "title": string,     "description": string,     "thumbnails": {       (key): {         "url": string,         "width": unsigned integer,         "height": unsigned integer       }     },     "channeltitle": string,     "playlistid": string,     "position": unsigned integer,     "resourceid": {       "kind": string,       "videoid": string,     }   },   "contentdetails": {     "videoid": string,     "startat": string,     "endat": string,     "note": string,     "videopublishedat": datetime   },   "status": {     "privacystatus": string   } } 

from structure, may suppose there 3 ways videoid. first important know how going define parts , fields of resource.

to define parts use code:

youtube.playlistitems.list list = youtube.playlistitems().list("snippet"); 

in previous line, "snippet" identifies property contains numerous fields (or child properties), including title, description, position, , resourceid, when set "snippet" api's response contain of child properties.

now, can limit previous properties if define fields. example, in code:

list.setfields("items(id/videoid,snippet/title,snippet/description," +     "snippet/thumbnails/default/url)"); 

if call list.execute(), show error because didn't define id in parts properties. also, according json structure, id string , not contains videoid child property. ah!, can extract videoid resourceid? -well, answers yes/no. -why so? come on teo, json structure shows clearly. -yes, can see that, documentation says:

if snippet.resourceid.kind property's value youtube#video, property present , value contain id youtube uses uniquely identify video in playlist.

this means sometimes may not available. -then, how can videoid? -well, can add id or contentdetails parts resources. if add id defines fields this:

youtube.playlistitems.list list = youtube.playlistitems().list("id,snippet"); list.setfields("items(id,snippet/title,snippet/description," +     "snippet/thumbnails/default/url)"); 

if add contentdetails defines fields this:

youtube.playlistitems.list list = youtube.playlistitems()     .list("snippet,contentdetails"); list.setfields("items(contentdetails/videoid,snippet/title,snippet/description," +     "snippet/thumbnails/default/url)"); 

i hope helps guys.