获取未解决的参考：导入时使用NotificationCompat

Question

NotificationCompat的导入给我以下错误

  

未解决的参考：NotificationCompat

我试图更改为     导入android.support.v7.app.NotificationCompat 但也没有用 我重新同步了无济于事的项目 我也重建了没有帮助的项目

import android.annotation.SuppressLint
import android.util.Log
import com.google.firebase.messaging.FirebaseMessagingService
import com.google.firebase.messaging.RemoteMessage
import android.app.NotificationManager
import android.media.RingtoneManager
import android.app.PendingIntent
import android.content.Context
import android.content.Intent
import android.support.v4.app.NotificationCompat


class MyFirebaseMessagingService : FirebaseMessagingService() {
    val TAG = "FirebaseMessagingService"

    @SuppressLint("LongLogTag")
    override fun onMessageReceived(remoteMessage: RemoteMessage) {
        Log.d(TAG, "Dikirim dari: ${remoteMessage.from}")

        if (remoteMessage.notification != null) {
            showNotification(remoteMessage.notification?.title, remoteMessage.notification?.body)
        }
    }

    private fun showNotification(title: String?, body: String?) {
        val intent = Intent(this, MainActivity::class.java)
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)
        val pendingIntent = PendingIntent.getActivity(this, 0, intent,
            PendingIntent.FLAG_ONE_SHOT)

        val soundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION)
        val notificationBuilder = NotificationCompat.Builder(this)
            .setSmallIcon(R.mipmap.ic_launcher)
            .setContentTitle(title)
            .setContentText(body)
            .setAutoCancel(true)
            .setSound(soundUri)
            .setContentIntent(pendingIntent)

        val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
        notificationManager.notify(0, notificationBuilder.build())
    }
}