三秒变换标题

Handler handler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        String str = (String) msg.obj;
        tv.setText(str);
    }
};
private Myadapter m;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tv = (TextView) findViewById(R.id.tv);
    lv = (ListView) findViewById(R.id.lv);
    m = new Myadapter();
    lv.setAdapter(m);
    new Myasny().execute(urlstr);
    new Thread() {

        private List<book.DataBean> data;
        private String news_title;

        @Override
        public void run() {
            String settext = Dao.Settext(str);
            Gson g = new Gson();
            final book bo = g.fromJson(settext, book.class);
            data = bo.getData();
            Timer t = new Timer();
            TimerTask tt = new TimerTask() {
                int i = 0;

                @Override
                public void run() {

                    if (i <= data.size() - 1) {
                        Message message = handler.obtainMessage();
                        news_title = data.get(i).getNews_title();
                        message.obj = news_title;
                        handler.sendMessage(message);
                        i++;
                    } else if (i == data.size()) {
                        i = 0;
                        Message message = handler.obtainMessage();
                        news_title = data.get(i).getNews_title();
                        message.obj = news_title;
                        handler.sendMessage(message);
                        i++;
                    }
                }

            };
            t.schedule(tt, 0, 3000);

        }
    }.start();