android - Attempt to invoke virtual method on a null object reference error -

i'm trying create song object insert object based array list (for music player app). song object should contain properties album, artist, title, etc.

however, app crashes when run program, , error in log cat.

java.lang.nullpointerexception: attempt invoke virtual method 'boolean java.util.arraylist.add(java.lang.object)' on null object reference 

here main class:

private listview listview1;  // list of song objects private arraylist<song> songobectlist;  // song object passed songobjectlist private song songobject = new song();  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);      // add song objects songobjectlist     getmusic();      // initialize adapter     songadapter adapter = new songadapter(this, r.layout.listview_item_row, songobectlist);      // initialize listview     listview1 = (listview)findviewbyid(r.id.listview1);      // initialize header     view header = (view)getlayoutinflater().inflate(r.layout.listview_header_row, null);      // add header listview     listview1.addheaderview(header);      // add adapter listview     listview1.setadapter(adapter);   private void getmusic() {      // set uri     uri contenturi = mediastore.audio.media.external_content_uri;      // set projection parameter getcontentresolver query     string[] projection = {             mediastore.audio.media.album,             mediastore.audio.media.artist,             mediastore.audio.media.title,             mediastore.audio.media.data,             mediastore.audio.media.duration     };      // run getcontentresolver query     final cursor mcursor = getcontentresolver().query(             contenturi, projection, null, null, null     );      // set song object properties      if (mcursor.movetofirst()) {         {              songobject.album = mcursor.getstring(0);             songobject.artist = mcursor.getstring(1);             songobject.title = mcursor.getstring(2);             songobject.data = mcursor.getstring(3);             songobject.duration = mcursor.getstring(4);              songobectlist.add(songobject);          } while (mcursor.movetonext());     }      mcursor.close();      return; } 

i don't see initialize songobectlist.

try replacing

// list of song objects private arraylist<song> songobectlist; 

with

// list of song objects private arraylist<song> songobectlist = new arraylist<song>();