通知栏报错 :Failed to post notification on channel "null"

public class DelayedMessageService extends IntentService {

    public static  final  int NOTIFICATION_ID=5453;

    public static final  String EXTRA_MESSAGE="message";
    public DelayedMessageService() {
        super("DelayedMessageService");
    }

    @Override
    protected void onHandleIntent(Intent intent) {
      synchronized (this){
          try{
              wait(3000);
          }catch (InterruptedException e){
              e.printStackTrace();
          }
      }
      String text=intent.getStringExtra(EXTRA_MESSAGE);
        Log.i("DelayedMessageService","The message is:"+text);

        NotificationCompat.Builder builder=new NotificationCompat.Builder(this)
                .setSmallIcon(android.R.drawable.sym_def_app_icon)
                .setContentTitle(getString(R.string.question))
                .setContentText(text)
                
                .setPriority(NotificationCompat.PRIORITY_HIGH)
                .setVibrate(new long[]{0,1000})
                .setAutoCancel(true);


        Intent actionIntent=new Intent(this,MainActivity.class);
        PendingIntent actionPendingIntent=PendingIntent.getActivity(
                this,
                0,
                actionIntent,
                PendingIntent.FLAG_CANCEL_CURRENT);
        builder.setContentIntent(actionPendingIntent);

        NotificationManager notificationManager=
                (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
        notificationManager.notify(NOTIFICATION_ID,builder.build());
    }
}

• 给你找了一篇非常好的博客，你可以看看是否有帮助，链接：解决Fail to post notification on channel "null"的方法

应该是兼容适配的问题，上网搜一搜