Why is the file not saved in External Storage?

Question

Android

I study data storage in Android according to the book Saving Data on Android by raywenderlich.
Their example uses the methods of such a repository.

class ExternalFileRepository(var context: Context) :
    NoteRepository {

  override fun addNote(note: Note) {
    if (isExternalStorageWritable()) {
      FileOutputStream(noteFile(note.fileName)).use { output ->
        output.write(note.noteText.toByteArray())
      }
    }
  }

  override fun getNote(fileName: String): Note {
    val note = Note(fileName, "")
    if (isExternalStorageReadable()) {
      FileInputStream(noteFile(fileName)).use { stream ->
        val text = stream.bufferedReader().use {
          it.readText()
        }
        note.noteText = text
      }
    }
    return note
  }

  override fun deleteNote(fileName: String): Boolean {
    return isExternalStorageWritable() && noteFile(fileName).delete()
  }

  private fun noteDirectory(): File? = context.getExternalFilesDir(null)

  private fun noteFile(fileName: String): File = File(noteDirectory(), fileName)

  fun isExternalStorageWritable(): Boolean {
    return Environment.getExternalStorageState() == Environment.MEDIA_MOUNTED
  }

  fun isExternalStorageReadable(): Boolean {
    return Environment.getExternalStorageState() in
        setOf(Environment.MEDIA_MOUNTED, Environment.MEDIA_MOUNTED_READ_ONLY)
  }

}

Permission in manifest

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

The problem is that the file is not saved along the path sdcard/data/app_name , and indeed it is not saved anywhere.
smartphone - Meizu m8, Android 8.1 Oreo
What could be the problem?

The isExternalStorageWritable() method returns true, and the file writing code is executed.

Answer 1

You need to request permission from the user
https://developer.android.com/guide/topics/permiss...
https://source.android.com/devices/tech/config/run...