Android图片轮播

if (autoSwitchpicTask==null){
            autoSwitchpicTask = new AutoSwitchPicTask();
            autoSwitchpicTask.start();
        }else {
            autoSwitchpicTask.start();

        }
    }
    class AutoSwitchPicTask extends Handler implements Runnable {
        /**
         * 开启任务
         */
        public void start() {
            stop();
            postDelayed(this, 3000);
        }
        /**
         * 关闭任务
         */
        public void stop() {
            removeCallbacks(this);
        }

        @Override
        public void run() {

            int position = viewPager.getCurrentItem();
            System.out.println("position "+position);
            if (position != viewPager.getAdapter().getCount() - 1) {

                viewPager.setCurrentItem(++position);

            } else {

                viewPager.setCurrentItem(0);
            }
                postDelayed(this, 3000);
        }

    }