//use Handler.obtainMessage(),instead of msg = new Message();
//because if there is already an Message object,that not be used by 
//any one ,the system will hand use that object,so you don‘t have to 
//create and object and allocate memory.
//it  is also another example of object recycling and reusing in android.
    Message msg = mHandler.obtainMessage();
    msg.what = UPDATE_LISTVIEW;
    msg.obj = current + "/" + total + "songs";
    //this method is called from worker Thread,so we cannot update UI from here.
    msg.sendToTarget();

Message msg = handler.obtainMessage();
                        msg.arg1 = i;
                        msg.sendToTarget(); 

Message msg=new Message();
    msg.arg1=i;
    handler.sendMessage(msg);