倒计时:

private int recLen = 6;
 
    private Timer timer = new Timer();       
         //倒计时方法
        TimerTask timerTask = new TimerTask() {
             @Override
             public void run() {
                 runOnUiThread(new Runnable() {
                     @Override
                     public void run() {
                         recLen--;
                         textView.setText(recLen+"秒后自动进入");
                         if(recLen < 1){
                             timer.cancel();    //小于1秒,关闭计时
                            Intent intent = new Intent(MainActivity.this, HomeActivity.class);
                             startActivity(intent);   //跳转下一界面
                            finish();    //结束当前界面
                        }
                     }
                 });
             }
         };

        timer.schedule(timerTask, 1000, 1000);

 

计时:

private int recLen = 0;
     private TextView txtView;

         final Handler handler = new Handler();
         Runnable runnable = new Runnable() {
             @Override
             public void run() {
                 recLen++;
                 txtView.setText(recLen+"秒");
                 handler.postDelayed(this, 1000);
             }
         };
         handler.postDelayed(runnable, 1000);