I come to you in a time of great need. I am currently learning to use Kotlin for app development and as a "project" per-say, I am working on a simple "File manager". The current problem I am experiencing is that I am unable to read the directories and the files.
Using API 26
Using Kotlin
Using ViewModel
The permissions in the AndroidManifest.xml are set
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
The permission request in runtime is called in MainActivity
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
if (checkPermission()) {
//permission allowed
val path = Environment.getExternalStorageDirectory().path
val filesAndFolders: Array<File>? = File(path).listFiles()
Log.d("FILETAG", path) // /storage/emulated/0
Log.d("FILETAG", filesAndFolders.toString()) // null
Log.d("FILETAG", File(path).exists().toString()) // true
Log.d("FILETAG", File(path).canRead().toString()) // false
} else {
//permission not allowed
requestPermission()
}
if (savedInstanceState == null) {
supportFragmentManager.beginTransaction()
.replace(R.id.container, MainFragment.newInstance())
.commitNow()
}
}
}
private fun checkPermission(): Boolean {
val result =
ContextCompat.checkSelfPermission(
this,
android.Manifest.permission.READ_EXTERNAL_STORAGE
)
return result == PackageManager.PERMISSION_GRANTED
}
private fun requestPermission(){
if(ActivityCompat.shouldShowRequestPermissionRationale(this, android.Manifest.permission.READ_EXTERNAL_STORAGE)){
Toast.makeText(this, "Storage permission is required", Toast.LENGTH_SHORT).show()
} else {
ActivityCompat.requestPermissions(
this,
arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE),
111
)
}
}
As commented in the code, the file array is returned as a "null", though the files seem to exist but are unreadable.
Additionally, I have tried executing this code from an inside of the fragment, but with the exact same results, though am required to read the files in a fragment rather than inside the MainActivity (But I first need to get this part of my code working before I move on to the fragments) and list the files in a RecyclerView.
This is my first question on Stackoverflow, if I missed any essential detail, let me know.
Please grant me your infinite knowledge, thank you.
Related
I usually add a post_notification permission request to my app.
The strange thing is that when I request directly, the dialog will not pop up.
But if I create the Notification channel first, I can jump out of the dialog normally,
Has anyone encountered the same situation? Or is there something wrong with my settings? Thanks!
AndroidManifest.xml
<uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
Fragement:
override fun onViewCreated(view: View, savedInstanceState: Bundle?)
{
super.onViewCreated(view, savedInstanceState)
requestPermissionLauncher =
registerForActivityResult(ActivityResultContracts.RequestPermission()) {
if (it) {
LogUtil.d(TAG, "Grant POST_NOTIFICATION permission")
} else {
LogUtil.d(TAG, "Denied POST_NOTIFICATION permission")
}
}
}
#RequiresApi(Build.VERSION_CODES.TIRAMISU)
override fun onResume()
{
if (ContextCompat.checkSelfPermission(
activity!!.applicationContext,
Manifest.permission.POST_NOTIFICATIONS,
) == PackageManager.PERMISSION_DENIED
) {
requestPermissionLauncher.launch(Manifest.permission.POST_NOTIFICATIONS)
}
}
Situation 1
if I add createNotificationChannel() before request permisssion,it work.
private fun createNotificationChannel() {
val channel = NotificationChannel(
CHANNEL_ID,
"Important Notification Channel",
NotificationManager.IMPORTANCE_HIGH,
).apply {
description = "This notification contains important announcement, etc."
}
notificationManager.createNotificationChannel(channel)
}
Situation 2
When I mark createNotificationChannel(),the dialog would not showing anymore.
After adding the Log, I found that,
After executing requestPermissionLauncher.launch(Manifest.permission.POST_NOTIFICATIONS),
there is no log jumping out,
just get the return of registerForActivityResult = false,
but I opened the app for the first time, and I have not rejected the notifcaiton permission.
I want to know how to fix it?
Step # 1
Can you change this
== PackageManager.PERMISSION_DENIED
to
!= PackageManager.PERMISSION_GRANTED
Step # 2
Ask for shouldShowRequestPermissionRationale, if user denies permission for once, on this official documentation
I am programming an app that connects to a device via Bluetooth, but every time I want to do something with the BluetoothDevice I have to insert a permission check like this (Kotlin):
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(
this,
arrayOf(Manifest.permission.BLUETOOTH_CONNECT),
42
)
}
Is there a workaround with one single permission check in the beginning of the app?
Thank you!
We have to check permission granted, otherwise it may crash your app.
but we can do in very handy way in Kotlin.
Follow below steps...
In your MainActivity or Very first activity, ask Bluetooth permission like below.
Create Permission Callback in Activity.
private val requestPermissionsLauncher = registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions()) { permissions ->
if (permissions.all { it.value }) Toast.makeText(
this,
"Permission Granted",
Toast.LENGTH_SHORT
).show()
else Toast.makeText(this, "not accepted all the permissions", Toast.LENGTH_LONG).show()
}
Request a permission in onCreate method of Activity.
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
//your code
requestPermissionsLauncher.launch(
arrayOf(android.Manifest.permission.BLUETOOTH_CONNECT)
) //asking permission whatever we need to run app.
}
Create a kotlin Extension function to make sure to run only on Bluetooth permission is Granted.
fun <T> Context.runOnBluetoothPermission(block: () -> T) {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) == PackageManager.PERMISSION_GRANTED) {
block()
} else {
Toast.makeText(
this,
"Bluetooth permission need to work this.",
Toast.LENGTH_SHORT
).show()
}
}
Use it extension function wherever you need.
example :
In SecondActivity.kt
class SecondActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
//ui functions
//apicalls if any
//functions that only run on Bluetooth permission
runOnBluetoothPermission{
getAllBluetoothDevices()
}
}
private fun getAllBluetoothDevices(){
//your code to get all bluetooth devices.
}
}
The user can revoke the permission at any time, by going to the app settings. When the permission is revoked, the activity will be recreated. This means you have to check at least once after onCreate and before using the permission, if you still have the permission.
TL;DR
No, your app might crash.
I have an activity that requires camera permission.
this activity can be called from several user configurable places in the app.
The rationale dialog and permission dialog themselves should be shown before the activity opens.
right now I am trying to handle these dialogs in some kind of extension function.
fun handlePermissions(context: Context, required_permissions: Array<String>, activity: FragmentActivity?, fragment: Fragment?): Boolean {
var isGranted = allPermissionsGranted(context, required_permissions)
if (!isGranted) {
//null here is where I used to pass my listener which was the calling fragment previously that implemented an interface
val dialog = DialogPermissionFragment(null, DialogPermissionFragment.PermissionType.QR)
activity?.supportFragmentManager?.let { dialog.show(it, "") }
//get result from dialog? how?
//if accepted launch actual permission request
fragment?.registerForActivityResult(ActivityResultContracts.RequestPermission()) { success ->
isGranted = success
}?.launch(android.Manifest.permission.CAMERA)
}
return isGranted
}
But I am having trouble to get the dialog results back from the rationale/explanation dialog.
My research until now brought me to maybe using a higher order function, to pass a function variable to the dialog fragment that returns a Boolean value to the helper function. But I am absolutely unsure if thats the right thing.
I thought using my own code would be cleaner and less overhead, could I achieve this easier when using a framework like eazy-permissions? (is Dexter still recommendable since its no longer under development)
is that even a viable thing I am trying to achieve here?
One approach that I've implemented and seems viable to use is this:
Class PermissionsHelper
class PermissionsHelper(private val activity: Activity) {
fun requestPermissionsFromDevice(
arrayPermissions: Array<String>, permissionsResultInterface: PermissionsResultInterface
) {
setPermissionResultInterface(permissionsResultInterface)
getMyPermissionRequestActivity().launch(arrayPermissions)
}
fun checkPermissionsFromDevice(permission: String): Boolean {
return ContextCompat.checkSelfPermission(activity, permission) ==
PackageManager.PERMISSION_GRANTED
}
}
Class PermissionsResultInterface to the helper class be able to communicate with the activity.
interface PermissionsResultInterface {
fun onPermissionFinishResult(permissions: MutableMap<String, Boolean>)
}
Usage with this approach to remove all files from app directory:
private fun clearFiles(firstCall: Boolean = false) {
if (verifyStoragePermissions(firstCall)) {
val dir = File(getExternalFilesDir(null).toString())
removeFileOrDirectory(dir)
Toast.makeText(
applicationContext,
resources.getString(R.string.done),
Toast.LENGTH_SHORT
).show()
}
}
private fun verifyStoragePermissions(firstCall: Boolean = false): Boolean {
val arrayListPermissions = arrayOf(
android.Manifest.permission.READ_EXTERNAL_STORAGE,
android.Manifest.permission.WRITE_EXTERNAL_STORAGE
)
for (permission in arrayListPermissions) {
if (!PermissionsHelper(this).checkPermissionsFromDevice(permission)) {
if (firstCall) PermissionsHelper(this)
.requestPermissionsFromDevice(arrayListPermissions, this)
else PermissionsDialogs(this).showPermissionsErrorDialog()
return false
}
}
return true
}
override fun onPermissionFinishResult(permissions: MutableMap<String, Boolean>) {
clearFiles()
}
With this approach you are able to call the permissions helper and using the result interface, after each of the answers from user, decide wether you still need to make a call for permissions or show a dialog to him.
If you need any help don't hesitate to contact me.
I am using MediaStore to recieve the ids of all the images stored on the device using
private fun getImageUris(): List<Uri> {
val uri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI
val projection = arrayOf(MediaStore.Images.Media._ID)
val mCursor = requireActivity().contentResolver.query(
uri,
projection,
null,
null,
null
)
val imageUris = mutableListOf<Uri>()
while (mCursor?.moveToNext() == true) {
val columnIndex = mCursor.getColumnIndex(MediaStore.Images.Media._ID)
val imageId = mCursor.getInt(columnIndex)
val currentImageUri = Uri.withAppendedPath(uri, imageId.toString())
imageUris.add(currentImageUri)
}
mCursor?.close()
return imageUris
}
and then i ask for the permission in onViewCreated() of my fragment like this:
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
binding = FragmentMainBinding.bind(view)
when {
isStoragePermissionGranted -> {
binding.recyclerView.adapter = RecyclerViewAdapter(getImageUris())
}
shouldShowRequestPermissionRationale -> {
Toast.makeText(mainActivity, "Please grant storage permission", Toast.LENGTH_SHORT).show()
requestPermissions(arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE), STORAGE_PERMISSION_REQUEST_CODE)
}
else -> {
Toast.makeText(mainActivity, "Permission not granted. Images cannot be shown.", Toast.LENGTH_SHORT).show()
}
}
}
I expect this to ask for the storage permission as soon as the app is opened (and my fragment is created) and then it should load all the images on the phone in my recycler view (I am using glide). But it doesn't work the way its expected to, instead the
"Permission not granted. Images cannot be shown."
toast message is shown
For a quick workaround, you can add this in the manifest file under <application>
android:requestLegacyExternalStorage="true"
Read about the storage update for Android 11 here
The problem was here as noted by #blackapps
shouldShowRequestPermissionRationale -> {
Toast.makeText(mainActivity, "Please grant storage permission", Toast.LENGTH_SHORT).show()
requestPermissions(arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE), STORAGE_PERMISSION_REQUEST_CODE)
because shouldShowRequestPermissionRationale is only true when the "deny and don't ask again" option is showing with the permission pop up and that option only appears after the first time the permission has been asked for (which never happens since in order for that to happen, shouldShowRequestPermissionRationale needs to be true).
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
use above permission and in application write below code:
<application
android:usesCleartextTraffic="true"
android:requestLegacyExternalStorage="true"/
In my application, i need to request write and read permission from the storage. Since i want to show the user that the app needs these permissions, i have created and Activity containing a button, which on click, should call the Storage permission Dialog.
However, since the recent Android changes, this doesnt work anymore.
Is there a new (and clean) way to ask permission? Am i doing something wrong?
I have added the uses-permission line inside the AndroidManifest.xml:
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
This is the code inside the Activity:
class ActivityPermission : AppCompatActivity() {
companion object {
var PERMISSION_REQUEST_CODE = 12
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityPermissionBinding.inflate(layoutInflater)
setContentView(R.layout.activity_permission)
binding.btnPermission.setOnClickListener {
ActivityCompat.requestPermissions(this, arrayOf(
android.Manifest.permission.READ_EXTERNAL_STORAGE,
android.Manifest.permission.WRITE_EXTERNAL_STORAGE),
PERMISSION_REQUEST_CODE)
}
}
override fun onRequestPermissionsResult(
requestCode: Int,
permissions: Array<out String>,
grantResults: IntArray
) {
if (requestCode == PERMISSION_REQUEST_CODE) {
if(grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
Toast.makeText(this, getString(R.string.permissiongranted), Toast.LENGTH_SHORT).show();
finish()
} else {
Toast.makeText(this, getString(R.string.permissiondenied), Toast.LENGTH_SHORT).show();
}
}
}
}
Thanks to everyone for helping me discover more about Android Permissions.
I decided to change the way i ask for the permission. Instead of an Activity, i decided to use a Fragment instead ("show an educational UI to the user. In this UI, describe why the feature, which the user wants to enable, needs a particular permission." - source | Thanks to #Michael in the comments for pointing it out).
Since now im using a Fragment, i have to use requestPermissions (Thanks to this reply). This now works flawlessly without any issues.
Turns out you need a combination of checks when trying to request a permission. You have to first check if the permission is actually enabled with checkSelfPermission, so you can easily choose where the user should go to start using the app.