1. 确保你的应用已经获得了适当的通知的权限。

2. 检查你的应用是否正确地实现了FCM的消息接收器，包括在AndroidManifest.xml中设置正确的 intent-filter，如下所示：

3. 确定你的应用程序正在推送正确格式的通知消息。以下是一个示例：

{
  "to" : "device_token",
  "notification" : {
      "title" : "FCM Notification",
      "body" : "This is a FCM Notification",
      "icon" : "icon_name"
  }
}

4. 在你的 MyFirebaseMessagingService.java 中，确保你正确地实现了 onMessageReceived 方法。以下是一个示例：

public class MyFirebaseMessagingService extends FirebaseMessagingService {
    private static final String TAG = "MyFirebaseMsgService";
  
    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        Log.d(TAG, "From: " + remoteMessage.getFrom());
        if (remoteMessage.getNotification() != null) {
            Log.d(TAG, "Notification Message Body: " + remoteMessage.getNotification().getBody());
        }
    }
}

5. 如果你的应用程序在运行时无法获取通知，则需要将其启动到前台。以下是一个示例：

public class MyFirebaseMessagingService extends FirebaseMessagingService {
    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        Intent intent = new Intent(this, MainActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(intent);

        NotificationCompat.Builder builder = new NotificationCompat.Builder(this)
                .setContentTitle(remoteMessage.getNotification().getTitle())
                .setContentText(remoteMessage.getNotification().getBody())
                .setSmallIcon(R.drawable.ic_notification)
                .setColor(ContextCompat.getColor(this, R.color.colorPrimary