Android Kotlin：需要上下文但找到字符串

Question

我正在尝试创建一种安排通知的方法。 在该方法中，我初始化了一个AlarmManager ，它允许我按需接收 Intents。 但是，我的代码中出现以下语法错误：

类型不匹配。 要求：找到的上下文：字符串

在以下行中：

 var alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager

下面是我的代码：

package com.example.notificationapp

import android.app.AlarmManager
import android.app.NotificationManager
import android.app.PendingIntent
import android.app.PendingIntent.getActivity
import android.content.Context
import android.content.Intent
import androidx.core.app.NotificationCompat
import androidx.core.content.ContextCompat.getSystemService
import java.security.AccessController.getContext
import java.util.*

// Channel

class Notification(context:Context, notificationManager: NotificationManager, title:String, description:String, date: Date) {
    // Attributes
    private lateinit var context:Context;
    private var title:String = ""
    private var description:String = ""
    private lateinit var date:Date;
    private lateinit var notificationManager:NotificationManager;

    // Initialization
    init {
        // Download the constructor parameters into the object's attributes
        this.context = context
        this.title = title
        this.description = description
        this.date = date
        this.notificationManager = notificationManager
    }

    // Method to set the notification at a specific time
    fun setNotificationAtTime(time:Date) {
        var notificationIntent = Intent(this.context, NotificationBroadcast::class.java)
        var pendingNotificationIntent = PendingIntent.getBroadcast(this.context,
            0, notificationIntent, 0)

        // Initialize an AlarmManager that allows us to receive intents on demand
        var alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager

        val builder = NotificationCompat.Builder(context, "com.example.notificationapp")
    }
}

Answer 1

这是因为您使用的是ContextCompat.getSystemService而不是Context.getSystemService 。

所以你在这里有两个选择：

1. 使用ContextCompat.getSystemService使用正确的签名：

getSystemService(context, AlarmManager::class.java)

2. 使用Context.getSystemService删除导入语句：

androidx.core.content.ContextCompat.getSystemService

Answer 2

在调用 getSystemService() 之前添加 requireActivity()

val alarmManager = requireActivity().getSystemService(Context.ALARM_SERVICE) as AlarmManager

Answer 3

2023解决方案：

// for NotificationManager
val alarmManager = getSystemService(requireContext(), NotificationManager::class.java)

// for InputMethodManager
val imm = getSystemService(requireContext(), InputMethodManager::class.java)