在使用JSONArray进行数据库预填充时，创建了表，但未插入数据。数据库创建（taskDao()不在伴随对象上）：

abstract fun taskDao(): TaskDao

@Volatile
private var INSTANCE: TaskDatabase? = null

fun getInstance(context: Context): TaskDatabase {
    return INSTANCE ?: synchronized(this) {
        val instance = Room.databaseBuilder(
            context.applicationContext,
            TaskDatabase::class.java,
            "task.db"
        ).addCallback(object : Callback() {
            override fun onCreate(db: SupportSQLiteDatabase) {
                super.onCreate(db)
                val dao = getInstance(context.applicationContext).taskDao()
                fillWithStartingData(context.applicationContext, dao)
            }
        }).build()
        INSTANCE = instance
        instance
    }
}

道：

@Insert(onConflict = OnConflictStrategy.REPLACE)
fun insertAll(vararg tasks: Task)

填充函数（执行Dao）：

private fun fillWithStartingData(context: Context, dao: TaskDao) {
    val task = loadJsonArray(context)
    try {
        if (task != null) {
            for (i in 0 until task.length()) {
                val item = task.getJSONObject(i)
                dao.insertAll(
                    Task(
                        item.getInt("id"),
                        item.getString("title"),
                        item.getString("description"),
                        item.getLong("dueDate"),
                        item.getBoolean("completed")
                    )
                )

                Log.d("Test", dao.getNearestActiveTask().toString())
            }
        }
    } catch (exception: JSONException) {
        exception.printStackTrace()
    }
}

JSON到JSONArray函数：

private fun loadJsonArray(context: Context): JSONArray? {
    val builder = StringBuilder()
    val `in` = context.resources.openRawResource(R.raw.task)
    val reader = BufferedReader(InputStreamReader(`in`))
    var line: String?
    try {
        while (reader.readLine().also { line = it } != null) {
            builder.append(line)
        }
        val json = JSONObject(builder.toString())
        return json.getJSONArray("tasks")
    } catch (exception: IOException) {
        exception.printStackTrace()
    } catch (exception: JSONException) {
        exception.printStackTrace()
    }
    return null
}

JSON：

{
  "tasks": [
    {
      "id": 1,
      "title": "Belajar AAD",
      "description": "Belajar dasar-dasar materi di kelas Dicoding",
      "dueDate": 1577811600000,
      "completed": false
    },
    {
      "id": 2,
      "title": "Simulasi Ujian AAD",
      "description": "Mencoba mengerjakan project latihan AAD",
      "dueDate": 1655226000000,
      "completed": true
    },
    {
      "id": 3,
      "title": "Ambil Ujian AAD",
      "description": "Saatnya menjadi Associate Android Developer!",
      "dueDate": 1735578000000,
      "completed": false
    }
  ]
}

将上下文更改为context.applicationContext会得到相同的结果。