private Handler handler = new Handler(){ @Override public void handleMessage(Message msg) { strs.add(msg.obj.toString()); adapter .notifyDataSetChanged(); } }; new Thread(){ @Override public void run() { super .run(); try { sleep ( 2000 ); } catch (InterruptedException e) { e.printStackTrace(); } Message msg= new Message(); msg. obj = "hello" ; handler.sendMessage(msg); } }.start(); private Handler handler = new Handler(); ============================================================ handler .post( new Runnable() { @Override public void run() { strs .add( "handler post" ); adapter .notifyDataSetChanged(); ...