检查以下代码并确保正确设置通知渠道：

private void createNotificationChannel() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        CharSequence name = "Channel Name";
        String description = "Channel Description";
        int importance = NotificationManager.IMPORTANCE_DEFAULT;
        NotificationChannel channel = new NotificationChannel("channel_id", name, importance);
        channel.setDescription(description);
        NotificationManager notificationManager = getSystemService(NotificationManager.class);
        notificationManager.createNotificationChannel(channel);
    }
}

确保在发送通知之前调用上述方法：

createNotificationChannel();
NotificationCompat.Builder builder = new NotificationCompat.Builder(this, "channel_id")
        .setSmallIcon(R.drawable.notification_icon)
        .setContentTitle("Notification Title")
        .setContentText("Notification Content")
        .setPriority(NotificationCompat.PRIORITY_DEFAULT);

NotificationManagerCompat notificationManager = NotificationManagerCompat.from(this);
notificationManager.notify(notificationId, builder.build());