无法启动接收器lateinit属性notificationManager尚未初始化

Question

我正在尝试使警报在关闭应用程序时发送通知。我在MainActivity中创建了一个警报管理器，并在触发onReceive()后立即为BroadcastReceiver创建了一个内部类，我需要发送通知。警报有效，但是每次尝试发送通知时，都会出现[]]错误

2020-03-25 13：19：33.166 15045-15045 / com.kotlin.ambulantlcsE / AndroidRuntime：致命异常：main流程：com.kotlin.ambulantlcs，PID：15045java.lang.RuntimeException：无法启动接收器com.kotlin.ambulantlcs.ui.MainActivity $ Receiver：kotlin.UninitializedPropertyAccessException：lateinit属性notificationManager尚未初始化在android.app.ActivityThread.handleReceiver（ActivityThread.java:3997）在android.app.ActivityThread.access $ 1500（ActivityThread.java:267）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1992）在android.os.Handler.dispatchMessage（Handler.java:107）在android.os.Looper.loop（Looper.java:237）在android.app.ActivityThread.main（ActivityThread.java:7777）在java.lang.reflect.Method.invoke（本机方法）在com.android.internal.os.RuntimeInit $ MethodAndArgsCaller.run（RuntimeInit.java:493）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1047）原因：kotlin.UninitializedPropertyAccessException：lateinit属性notificationManager尚未初始化在com.kotlin.ambulantlcs.ui.MainActivity $ Receiver.onReceive（MainActivity.kt：100）在android.app.ActivityThread.handleReceiver（ActivityThread.java:3988）在android.app.ActivityThread.access $ 1500（ActivityThread.java:267）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1992）在android.os.Handler.dispatchMessage（Handler.java:107）在android.os.Looper.loop（Looper.java:237）在android.app.ActivityThread.main（ActivityThread.java:7777）在java.lang.reflect.Method.invoke（本机方法）在com.android.internal.os.RuntimeInit $ MethodAndArgsCaller.run（RuntimeInit.java:493）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1047）

请在下面查看我的完整代码。

import android.app.*
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.graphics.Color
import android.os.Build
import android.os.Bundle
import android.util.Log
import android.widget.RemoteViews
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.navigation.NavOptions
import androidx.navigation.Navigation
import androidx.navigation.ui.AppBarConfiguration
import androidx.navigation.ui.NavigationUI
import com.kotlin.ambulantlcs.R
import com.kotlin.ambulantlcs.storage.SharedDataManager
import com.kotlin.ambulantlcs.ui.fragments.LoginFragmentDirections
import java.util.*


open class MainActivity : AppCompatActivity() {

    lateinit var context: Context
    lateinit var alarmManager: AlarmManager
    val obj: MainActivity = this

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val appBarConfiguration = AppBarConfiguration
            .Builder(R.id.homeFragment, R.id.loginFragment)
            .build()

        setAlarm()

        if(SharedDataManager.getInstance(this).isLoggedIn) {
            var navOptions = NavOptions.Builder()
                .setPopUpTo(R.id.action_login_Home, true)
                .build()

            val navController = Navigation.findNavController(this, R.id.fragment)
            NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration)
            navController.navigate(
                LoginFragmentDirections.actionLoginHome()
            )
        } else {
            val navController = Navigation.findNavController(this, R.id.fragment )
            NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration)

        }
    }


    override fun onBackPressed() {
        Toast.makeText(applicationContext, "Function is not allowed", Toast.LENGTH_SHORT).show()
    }

    override fun onSupportNavigateUp(): Boolean {
        return NavigationUI.navigateUp(Navigation.findNavController(this, R.id.fragment), null)
    }

    fun setAlarm() {
        Log.d("MainActivity", "Create: ${Date().toString()}")
        context = this
        alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
        val seconds = 10 * 1000
        val intent = Intent(context, Receiver::class.java)
        val pendingIntent = PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT)
        Log.d("MainActivity", "SECONDS: ${seconds.toLong()}")
        alarmManager.setRepeating(AlarmManager.RTC_WAKEUP,  seconds.toLong(), seconds.toLong(), pendingIntent)
    }

    class Receiver : BroadcastReceiver() {
        lateinit var notificationManager : NotificationManager
        lateinit var notificationChannel : NotificationChannel
        lateinit var builder : Notification.Builder
        private val channelId = "i.apps.notifications"
        private val description = "Test notification"

        override fun onReceive(context: Context?, intent: Intent?) {
           Log.d("MainActivity", " Receiver: ${Date().toString()}")
            val intent = Intent(context, MainActivity::class.java)

            val pIntent = PendingIntent.getActivity(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT)
            val contentView = RemoteViews("com.kotlin.ambulantlcs",
                R.layout.activity_main)

            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                notificationChannel = NotificationChannel(
                    channelId,description,NotificationManager.IMPORTANCE_HIGH)
                notificationChannel.enableLights(true)
                notificationChannel.lightColor = Color.GREEN
                notificationChannel.enableVibration(false)
                notificationManager.createNotificationChannel(notificationChannel)

                builder = Notification.Builder(context, channelId)
                    .setContent(contentView)
                    .setSmallIcon(R.drawable.ic_launcher_background)
                    .setContentIntent(pIntent)
            }else{

                builder = Notification.Builder(context)
                    .setContent(contentView)
                    .setSmallIcon(R.drawable.ic_launcher_background)
                    .setContentIntent(pIntent)
            }
            notificationManager.notify(1234,builder.build())
        }
    }
}
您能帮我解决这个问题吗？谢谢。

我正在尝试使警报在关闭应用程序时发送通知。我在MainActivity中创建了一个警报管理器，并在...

Answer 1

您的notificationManger为空（您不初始化他）。试试这个：

Answer 2

应用程序崩溃的原因是您没有初始化notificationManager。除了将其声明为lateinit var之外，您还可以在Receiver类中将其初始化：