Fixed crashing when selecting folders

app/build.gradle

@@ -10,8 +10,8 @@ android {
         applicationId "com.sc.gtradio"
         minSdkVersion 24
         targetSdkVersion 30
-        versionCode 1
-        versionName "1.0"
+        versionCode 3
+        versionName "1.0.1"
 
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }

app/proguard-rules.pro

@@ -14,7 +14,7 @@
 
 # Uncomment this to preserve the line number information for
 # debugging stack traces.
-#-keepattributes SourceFile,LineNumberTable
+-keepattributes SourceFile,LineNumberTable
 
 # If you keep the line number information, uncomment this to
 # hide the original source file name.

app/src/main/java/com/sc/gtradio/GroupList.kt

@@ -29,6 +29,19 @@ class GroupList : Fragment() {
 
     private val subscriptionCallback = object : MediaBrowserCompat.SubscriptionCallback() {
         override fun onChildrenLoaded(parentId: String, children: List<MediaBrowserCompat.MediaItem>) {
+            if (_binding != null) {
+                val sharedPref = PreferenceManager.getDefaultSharedPreferences(requireActivity().applicationContext)
+                val radioUri = sharedPref?.getString(getString(R.string.radio_folders_uri_key), "")
+
+                if (children.isEmpty() && activity?.contentResolver?.persistedUriPermissions?.any { x -> x.uri == Uri.parse(radioUri) && x.isReadPermission } == true) {
+                    //No stations listed and we have already selected a library, so show our nothing-found message
+                    binding.textviewNogroups.visibility = View.VISIBLE
+                    binding.sadFaceIcon.visibility = View.VISIBLE
+                } else {
+                    binding.textviewNogroups.visibility = View.INVISIBLE
+                    binding.sadFaceIcon.visibility = View.INVISIBLE
+                }
+            }
             listAdapter.submitList(children)
         }
     }
@@ -53,7 +66,10 @@ class GroupList : Fragment() {
     }
 
     private val permissionResultLauncher = registerForActivityResult(contract)
-    { result: Uri ->
+    { result: Uri? ->
+        if (result == null) {
+            return@registerForActivityResult
+        }
         activity?.contentResolver?.takePersistableUriPermission(result, Intent.FLAG_GRANT_READ_URI_PERMISSION)
         val sharedPref = PreferenceManager.getDefaultSharedPreferences(activity?.applicationContext)
         with (sharedPref?.edit()) {
@@ -118,9 +134,17 @@ class GroupList : Fragment() {
         val sharedPref = PreferenceManager.getDefaultSharedPreferences(this.requireActivity().applicationContext)
         val radioUri = sharedPref?.getString(getString(R.string.radio_folders_uri_key), "")
         if (radioUri.isNullOrEmpty() || activity?.contentResolver?.persistedUriPermissions?.any { x -> x.uri == Uri.parse(radioUri) && x.isReadPermission } != true) {
-            //User has no library selected, allow them to select something
+            //User has no library selected, allow them to select something and possibly reset our pref value
+            if (!radioUri.isNullOrEmpty()) {
+                with (sharedPref?.edit()) {
+                    this?.putString(getString(R.string.radio_folders_uri_key), "")
+                    this?.apply()
+                }
+            }
             binding.buttonSelect.visibility = View.VISIBLE
             binding.textviewNofolder.visibility = View.VISIBLE
+            binding.textviewNogroups.visibility = View.INVISIBLE
+            binding.sadFaceIcon.visibility = View.INVISIBLE
         } else {
             binding.buttonSelect.visibility = View.INVISIBLE
             binding.textviewNofolder.visibility = View.INVISIBLE
@@ -129,6 +153,8 @@ class GroupList : Fragment() {
 
     override fun onDestroyView() {
         super.onDestroyView()
+        val sharedPref = PreferenceManager.getDefaultSharedPreferences(this.requireActivity().applicationContext)
+        sharedPref.unregisterOnSharedPreferenceChangeListener(sharedPrefListener)
         _binding = null
     }
 }

app/src/main/java/com/sc/gtradio/SettingsActivity.kt

@@ -1,8 +1,14 @@
 package com.sc.gtradio
 
+import android.content.Context
+import android.content.Intent
+import android.net.Uri
 import android.os.Bundle
+import androidx.activity.result.contract.ActivityResultContracts
 import androidx.appcompat.app.AppCompatActivity
+import androidx.preference.Preference
 import androidx.preference.PreferenceFragmentCompat
+import androidx.preference.PreferenceManager
 
 class SettingsActivity : AppCompatActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -18,9 +24,38 @@ class SettingsActivity : AppCompatActivity() {
     }
 
     class SettingsFragment : PreferenceFragmentCompat() {
+        private val contract = object : ActivityResultContracts.OpenDocumentTree() {
+            override fun createIntent(context: Context, input: Uri?): Intent {
+                val intent = super.createIntent(context, input)
+                intent.addFlags(Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION)
+                intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+                intent.addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
+                return intent
+            }
+        }
+
+        private val permissionResultLauncher = registerForActivityResult(contract)
+        { result: Uri? ->
+            if (result == null) {
+                return@registerForActivityResult
+            }
+            activity?.contentResolver?.takePersistableUriPermission(result, Intent.FLAG_GRANT_READ_URI_PERMISSION)
+            val sharedPref = PreferenceManager.getDefaultSharedPreferences(activity?.applicationContext)
+            with (sharedPref?.edit()) {
+                this?.putString(getString(R.string.radio_folders_uri_key), result.toString())
+                this?.apply()
+            }
+
+        }
 
         override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
             setPreferencesFromResource(R.xml.root_preferences, rootKey)
+
+            val pathPref = findPreference<Preference>(getString(R.string.radio_folders_uri_key))
+            pathPref?.setOnPreferenceClickListener {
+                permissionResultLauncher.launch(null)
+                true
+            }
         }
     }
 }

app/src/main/res/drawable/ic_sad_face.xml

@@ -0,0 +1,16 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="?attr/colorControlNormal">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M15.5,9.5m-1.5,0a1.5,1.5 0,1 1,3 0a1.5,1.5 0,1 1,-3 0"/>
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M8.5,9.5m-1.5,0a1.5,1.5 0,1 1,3 0a1.5,1.5 0,1 1,-3 0"/>
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M12,14c-2.33,0 -4.32,1.45 -5.12,3.5h1.67c0.69,-1.19 1.97,-2 3.45,-2s2.75,0.81 3.45,2h1.67c-0.8,-2.05 -2.79,-3.5 -5.12,-3.5zM11.99,2C6.47,2 2,6.48 2,12s4.47,10 9.99,10C17.52,22 22,17.52 22,12S17.52,2 11.99,2zM12,20c-4.42,0 -8,-3.58 -8,-8s3.58,-8 8,-8 8,3.58 8,8 -3.58,8 -8,8z"/>
+</vector>

app/src/main/res/layout/fragment_grouplist.xml

@@ -17,7 +17,7 @@
         app:layout_constraintHorizontal_bias="0.498"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@id/textview_nofolder"
-        tools:visibility="invisible" />
+        android:visibility="invisible" />
 
     <TextView
         android:id="@+id/textview_nofolder"
@@ -28,7 +28,35 @@
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent"
-        tools:visibility="invisible" />
+        android:visibility="invisible" />
+
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:padding="32dp">
+
+        <ImageView
+            android:id="@+id/sadFaceIcon"
+            android:layout_width="64dp"
+            android:layout_height="64dp"
+            android:contentDescription="@string/sad_face"
+            android:src="@drawable/ic_sad_face"
+            android:visibility="invisible"
+            app:layout_constraintBottom_toTopOf="@id/textview_nogroups"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"/>
+
+        <TextView
+            android:id="@+id/textview_nogroups"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/no_groups_available"
+            android:visibility="invisible"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent" />
+    </androidx.constraintlayout.widget.ConstraintLayout>
 
     <androidx.recyclerview.widget.RecyclerView
         android:id="@+id/station_list"

app/src/main/res/values/strings.xml

@@ -34,5 +34,7 @@
     <string name="news_reports_summary">Note: This setting only affects gen 3 stations.</string>
 
     <string name="nothing_playing">Nothing Playing</string>
+    <string name="no_groups_available">No groups available. Double check the selected folder and your folder structure.</string>
+    <string name="sad_face">Sad face</string>
 
 </resources>

common/src/main/java/com/sc/gtradio/media/GTRadioMusicService.kt

@@ -331,7 +331,11 @@ open class GTRadioMusicService : MediaBrowserServiceCompat() {
         val list = ArrayList<StationGroup>()
         val subDirs = (dir?.listFiles() ?: emptyArray()).filter { x -> x.isDirectory }
         for (subDir in subDirs) {
-            list.add(StationGroup(subDir, applicationContext))
+            val group = StationGroup(subDir, applicationContext)
+            if (group.generation in 1..3) {
+                //Valid group.
+                list.add(group)
+            }
         }
         list.sortBy { x -> x.groupName }
         return list

common/src/main/java/com/sc/gtradio/media/stations/StationGroup.kt

@@ -16,8 +16,8 @@ class StationGroup(val folderDoc: DocumentFile, private val context: Context) {
 
     var mediaItem: MediaBrowserCompat.MediaItem
     var stationList: ArrayList<MediaBrowserCompat.MediaItem>
-    var generation: Int = 0
-    lateinit var groupName: String
+    var generation: Int = -1
+    var groupName: String = ""
 
     init {
         setupDataFromJson(folderDoc)
@@ -71,7 +71,7 @@ class StationGroup(val folderDoc: DocumentFile, private val context: Context) {
             jsonObj.getInt("generation")
         } catch (e: Exception) {
             //No valid generation
-            0
+            -1
         }
         groupName = try {
             jsonObj.getString("name")