第一行代码中的代码是基于android 7.0进行编写，API的调用已经落后较多

Notification 常用写法：

    private void showNotification() {
        Intent intent = FragmentTestActivity.formatIntent(this);
        PendingIntent pi = PendingIntent.getActivity(this, 0, intent, 0);
        NotificationManager notiManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        Notification notification = new Notification.Builder(this)
                .setContentTitle("title")
                .setContentText("test")
                .setWhen(System.currentTimeMillis())        //show time on notification
                .setSmallIcon(R.mipmap.ic_launcher_round)   //icon in the status bar
                .setAutoCancel(true)                        //cancel self when click notification
                .setContentIntent(pi)                       //set the intent handled when click notification
                .build();

        if(notiManager != null){
            notiManager.notify(1, notification);
        }
    }

手动关闭notification：

        NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        if(nm != null){
            //1 is the id, which should be the same int value when `notify(int id, Notification notification) called` 
            nm.cancel(1);
        }

NotificationChannel: 8.0 新增特性

下午学习