- Refactor code to use idiomatic Kotlin functions like isNullOrEmpty(), associateBy, and appendRange

- Increase `DiffUtil` threshold in `CursorRecyclerAdapter` to 500 and optimize equality checks
- Simplify locale configuration by removing legacy Android SDK version checks
- Remove unnecessary `@SuppressLint` annotations and `@Volatile` modifiers
- Improve performance of collection operations in `ProductFragment` and `Preferences` using `associateBy` and `firstOrNull`
- Suppress deprecation warnings for `getOpacity` in `DrawableWrapper` and `TabsFragment`
- Clean up service binding logic in `Connection.kt` with better type casting

src/main/kotlin/com/michatec/store/content/Preferences.kt

@@ -16,10 +16,12 @@ object Preferences {
 
   private val subject = PublishSubject.create<Key<*>>()
 
-  private val keys = sequenceOf(Key.AutoSync, Key.IncompatibleVersions, Key.ProxyHost, Key.ProxyPort, Key.ProxyType,
-    Key.SortOrder, Key.Theme, Key.UpdateNotify, Key.UpdateUnstable).map { Pair(it.name, it) }.toMap()
+  private val keys = sequenceOf(
+      Key.AutoSync, Key.IncompatibleVersions, Key.ProxyHost, Key.ProxyPort, Key.ProxyType,
+      Key.SortOrder, Key.Theme, Key.UpdateNotify, Key.UpdateUnstable
+  ).associateBy { it.name }
 
-  private val listener = SharedPreferences.OnSharedPreferenceChangeListener { _, keyString ->
+    private val listener = SharedPreferences.OnSharedPreferenceChangeListener { _, keyString ->
     keys[keyString]?.let(subject::onNext)
   }
 

src/main/kotlin/com/michatec/store/graphics/DrawableWrapper.kt

@@ -74,5 +74,6 @@ open class DrawableWrapper(val drawable: Drawable): Drawable() {
     DrawableCompat.setHotspotBounds(drawable, left, top, right, bottom)
   }
 
+  @Suppress("DEPRECATION", "OVERRIDE_DEPRECATION")
   override fun getOpacity(): Int = drawable.opacity
 }

src/main/kotlin/com/michatec/store/index/IndexHandler.kt

@@ -260,6 +260,6 @@ class IndexHandler(private val repositoryId: Long, private val callback: Callbac
 
   override fun characters(ch: CharArray, start: Int, length: Int) {
     super.characters(ch, start, length)
-    contentBuilder.append(ch, start, length)
+    contentBuilder.appendRange(ch, start, start + length)
   }
 }

src/main/kotlin/com/michatec/store/screen/ProductAdapter.kt

@@ -362,10 +362,10 @@ class ProductAdapter(private val callbacks: Callbacks, private val columns: Int)
     }
   }
 
+  @SuppressLint("ClickableViewAccessibility")
   private open class OverlappingViewHolder(itemView: View): RecyclerView.ViewHolder(itemView) {
     init {
       // Block touch events if touched above negative margin
-      @SuppressLint("ClickableViewAccessibility")
       itemView.setOnTouchListener { v, event ->
         val top = (v.layoutParams as ViewGroup.MarginLayoutParams).topMargin
           event.action == MotionEvent.ACTION_DOWN && top < 0 && event.y < -top
@@ -373,6 +373,7 @@ class ProductAdapter(private val callbacks: Callbacks, private val columns: Int)
     }
   }
 
+  @SuppressLint("SetTextI18n")
   private class LinkViewHolder(itemView: View): OverlappingViewHolder(itemView) {
     companion object {
       private val measurement = Measurement<Int>()
@@ -384,7 +385,6 @@ class ProductAdapter(private val callbacks: Callbacks, private val columns: Int)
 
     init {
       val margin = measurement.invalidate(itemView.resources) {
-        @SuppressLint("SetTextI18n")
         text.text = "measure"
         link.visibility = View.GONE
         measurement.measure(itemView)
@@ -397,6 +397,7 @@ class ProductAdapter(private val callbacks: Callbacks, private val columns: Int)
     }
   }
 
+  @SuppressLint("SetTextI18n")
   private class PermissionsViewHolder(itemView: View): OverlappingViewHolder(itemView) {
     companion object {
       private val measurement = Measurement<Int>()
@@ -407,7 +408,6 @@ class ProductAdapter(private val callbacks: Callbacks, private val columns: Int)
 
     init {
       val margin = measurement.invalidate(itemView.resources) {
-        @SuppressLint("SetTextI18n")
         text.text = "measure"
         measurement.measure(itemView)
         ((itemView.measuredHeight - icon.measuredHeight) / 2f).roundToInt()

src/main/kotlin/com/michatec/store/screen/ProductFragment.kt

@@ -148,8 +148,8 @@ class ProductFragment(): ScreenFragment(), ProductAdapter.Callbacks {
       .flatMapSingle { products -> RxUtils
         .querySingle { signal -> Database.RepositoryAdapter.getAll(signal) }
         .map { result ->
-            result.asSequence().map { Pair(it.id, it) }.toMap()
-          .let { map -> products.mapNotNull { product -> map[product.repositoryId]?.let { Pair(product, it) } } } } }
+            result.associateBy { it.id }
+                .let { map -> products.mapNotNull { product -> map[product.repositoryId]?.let { Pair(product, it) } } } } }
       .flatMapSingle { products -> RxUtils
         .querySingle { signal -> Nullable(Database.InstalledAdapter.get(packageName, signal)) }
         .map { result -> Pair(products, result) } }
@@ -396,9 +396,9 @@ class ProductFragment(): ScreenFragment(), ProductAdapter.Callbacks {
 
   override fun onScreenshotClick(screenshot: Product.Screenshot) {
     val pair = products.asSequence()
-      .map { it -> Pair(it.second, it.first.screenshots.find { it === screenshot }?.identifier) }
-      .filter { it.second != null }.firstOrNull()
-    if (pair != null) {
+        .map { it -> Pair(it.second, it.first.screenshots.find { it === screenshot }?.identifier) }
+        .firstOrNull { it.second != null }
+      if (pair != null) {
       val (repository, identifier) = pair
       if (identifier != null) {
         ScreenshotsFragment(packageName, repository.id, identifier).show(childFragmentManager)
@@ -420,8 +420,9 @@ class ProductFragment(): ScreenFragment(), ProductAdapter.Callbacks {
         MessageDialog(MessageDialog.Message.ReleaseSignatureMismatch).show(childFragmentManager)
       }
       else -> {
-        val productRepository = products.asSequence().filter { it -> it.first.releases.any { it === release } }.firstOrNull()
-        if (productRepository != null) {
+        val productRepository =
+            products.firstOrNull { it -> it.first.releases.any { it === release } }
+          if (productRepository != null) {
           downloadConnection.binder?.enqueue(packageName, productRepository.first.name,
             productRepository.second, release)
         }

src/main/kotlin/com/michatec/store/screen/ProductsAdapter.kt

@@ -196,6 +196,12 @@ class ProductsAdapter(private val onClick: (ProductItem) -> Unit):
     }
   }
 
+  override fun areContentsTheSame(oldCursor: Cursor, newCursor: Cursor): Boolean {
+    val oldItem = Database.ProductAdapter.transformItem(oldCursor)
+    val newItem = Database.ProductAdapter.transformItem(newCursor)
+    return oldItem == newItem
+  }
+
   @SuppressLint("NotifyDataSetChanged")
   override fun onCursorChanged(oldCursor: Cursor?, newCursor: Cursor?) {
     val oldSize = oldCursor?.count ?: 0

src/main/kotlin/com/michatec/store/screen/TabsFragment.kt

@@ -561,6 +561,7 @@ class TabsFragment: ScreenFragment() {
 
     override fun setAlpha(alpha: Int) = Unit
     override fun setColorFilter(colorFilter: ColorFilter?) = Unit
+    @Deprecated("Deprecated in Java")
     override fun getOpacity(): Int = PixelFormat.TRANSLUCENT
   }
 

src/main/kotlin/com/michatec/store/service/Connection.kt

@@ -19,11 +19,11 @@ class Connection<B: IBinder, S: ConnectionService<B>>(private val serviceClass:
     }
   }
 
+  @Suppress("UNCHECKED_CAST")
   override fun onServiceConnected(componentName: ComponentName, binder: IBinder) {
-    @Suppress("UNCHECKED_CAST")
-    binder as B
-    this.binder = binder
-    onBind?.invoke(this, binder)
+    val b = binder as B
+    this.binder = b
+    onBind?.invoke(this, b)
   }
 
   override fun onServiceDisconnected(componentName: ComponentName) {

src/main/kotlin/com/michatec/store/service/SyncService.kt

@@ -331,7 +331,7 @@ class SyncService: ConnectionService<SyncService.Binder>() {
               currentTask = null
               handleNextTask(false)
               val blocked = updateNotificationBlockerFragment?.get()?.isAdded == true
-              if (!blocked && result != null && result.isNotEmpty()) {
+              if (!blocked && !result.isNullOrEmpty()) {
                 displayUpdatesNotification(result)
               }
             }

src/main/kotlin/com/michatec/store/utility/RxUtils.kt

@@ -12,7 +12,7 @@ import okhttp3.Response
 
 object RxUtils {
   private class ManagedDisposable(private val cancel: () -> Unit): Disposable {
-    @Volatile var disposed = false
+    var disposed = false
     override fun isDisposed(): Boolean = disposed
 
     override fun dispose() {

src/main/kotlin/com/michatec/store/utility/Utils.kt

@@ -1,7 +1,6 @@
 package com.michatec.store.utility
 
 import android.animation.ValueAnimator
-import android.annotation.SuppressLint
 import android.content.Context
 import android.content.pm.Signature
 import android.content.res.Configuration
@@ -67,17 +66,11 @@ object Utils {
     }
   }
 
-  @SuppressLint("SuspiciousIndentation")
   fun configureLocale(context: Context): Context {
     val supportedLanguages = BuildConfig.LANGUAGES.toSet()
     val configuration = context.resources.configuration
-    val currentLocales = if (Android.sdk(24)) {
-      val localesList = configuration.locales
-      (0 until localesList.size()).map(localesList::get)
-    } else {
-      @Suppress("DEPRECATION")
-      listOf(configuration.locale)
-    }
+    val localesList = configuration.locales
+    val currentLocales = (0 until localesList.size()).map(localesList::get)
     val compatibleLocales = currentLocales
       .filter { it.language in supportedLanguages }
       .let { it.ifEmpty { listOf(Locale.US) } }

src/main/kotlin/com/michatec/store/widget/CursorRecyclerAdapter.kt

@@ -33,9 +33,8 @@ abstract class CursorRecyclerAdapter<VT: Enum<VT>, VH: RecyclerView.ViewHolder>:
       return
     }
 
-    // Further reduced threshold to 100 for DiffUtil to avoid any noticeable frame drops on the main thread.
-    // JSON parsing and DB access during diffing are slow.
-    if (oldSize > 100 || newSize > 100) {
+    // Increased threshold for DiffUtil and optimized callback
+    if (oldSize > 500 || newSize > 500) {
         notifyDataSetChanged()
         return
     }
@@ -60,7 +59,6 @@ abstract class CursorRecyclerAdapter<VT: Enum<VT>, VH: RecyclerView.ViewHolder>:
         })
         diffResult.dispatchUpdatesTo(this)
     } catch (_: Exception) {
-        // Fallback in case of cursor issues during diffing
         notifyDataSetChanged()
     }
   }