When the Parcelable interface in the class uses ArrayList < CustomObject > Android system: NullPointerException

I want to make calls to music using parcelable, so I can access the class of two instances of music in different activities. I don't want to use the purpose of serializable speed. When I try to use it to pass, I always receive nullpointerexception:

Intent in = getIntent();thisInstance = (Music) in.getExtras().get("MusicInstance");

Music classes: (ArrayList is at the bottom of the top and Parcelable Class)

public class Music implements parcelable{private static arraylist<genericsongclass> songs = new Arraylist<gen    Ericsongclass> ();    cursor cursor;    static context context;    Public Music (Context context) {This.context = context;    ' Public Music ' (Parcel in) {in.readtypedlist (songs, genericsongclass.creator); } public void Bindallsongs () {/** Making custom drawable */String selection = MediaStor            E.audio.media.is_music + "! = 0"; Final string[] projection = new string[] {MediaStore.Audio.Media.DISPLAY_NAME, Medi AStore.Audio.Media.ARTIST, MediaStore.Audio.Media.DATA, MediaStore.Audio.Media.ALBUM                    };                    Final String SortOrder = MediaStore.Audio.AudioColumns.TITLE + "COLLATE localized ASC";           try {//The URI of the table, we want to query             Uri uri = Android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; Query the DB cursor = Context.getcontentresolver (). Query (URI, pro                        Jection, selection, NULL, SortOrder);                            if (cursor! = null) {songs = new arraylist<genericsongclass> (Cursor.getcount ());                                                   Cursor.movetofirst ();                                while (!cursor.isafterlast ()) {Genericsongclass GSC = new Genericsongclass ();                                Gsc.songtitle = cursor.getstring (0);                                   Gsc.songartist = cursor.getstring (1);                                Gsc.songdata = cursor.getstring (2);                                Gsc.songalbum = cursor.getstring (3);                                Songs.add (GSC);           Cursor.movetonext ();                 }}} catch (Exception ex) {} finally {                        if (cursor! = NULL) {cursor.close (); }}} public static object[] ToArray (arraylist<object> list) {object[] to        Return = new Object[list.size ()];        for (int i = 0; i < list.size (); i++) {Toreturn[i] = List.get (i);    } return Toreturn;        } public arraylist<string> getartists () {arraylist<string> artists = new arraylist<string> (); for (Genericsongclass gsc:songs) {if (!artists.contains (gsc.songartist)) {Artists.add (GSC.            Songartist);        }} alphabetize forartists = new alphabetize (artists);    return Forartists.getsortedarraylist (); } public arraylist<string> Getalbums (String artist) {arraylist<string> albums = NEW arraylist<string> ();            for (Genericsongclass gsc:songs) {if (gsc.songartist = = artist) {Albums.add (gsc.songalbum);        }} alphabetize foralbums = new alphabetize (albums);    return Foralbums.getsortedarraylist ();  }//---Parcel------------------------------------------------public static final parcelable.creator<music>                  CREATOR = new Parcelable.creator<music> () {public Music createfromparcel (Parcel in) {              return new Music (in);            } @Override Public music[] NewArray (int size) {return new music[size];    }          };    @Override public int describecontents () {return 0;    } @Override public void Writetoparcel (Parcel dest, int flags) {dest.writelist (songs); }}

Genericsongclass:

public class Genericsongclass implements parcelable {String songtitle = "";    String songartist = "";    String songdata = "";    String songalbum = "";    Public Genericsongclass () {};        Private Genericsongclass (Parcel in) {songtitle = In.readstring ();        Songartist = In.readstring ();        Songdata = In.readstring ();    Songalbum = In.readstring (); public static final parcelable.creator<genericsongclass> Creator = new parcelable.creator<genericsongclass& gt; () {@Override public genericsongclass createfromparcel (Parcel source) {return new Genericson        Gclass (source);        } @Override Public genericsongclass[] NewArray (int size) {return new genericsongclass[size];    }    };    @Override public int describecontents () {return 0;        } @Override public void Writetoparcel (Parcel dest, int flags) {dest.writestring (songtitle);        Dest.writestring (songartist); Dest.WriteString (Songdata);    Dest.writestring (Songalbum); }}

Why do I get nullpointer and how do I remedy this situation?

This is the first time I have used parcelable, so any help suggestions are more popular. Thank you, first!

Workaround 1:

To Constructor.use please initialize your list with the following code.

public Music(Parcel in){        songs = new ArrayList<genericSongClass>();        in.readTypedList(songs, genericSongClass.CREATOR);    }

And get with this code:

thisInstance = getIntent().getParcelableExtra("MusicInstance");

Make sure that you initialize and thisInstance .

When the Parcelable interface in the class uses ArrayList < CustomObject > Android system: NullPointerException