Android GUI: Migrate Rx Java to Kotlin Coroutines

cjee21 · cjee21 · commit cd6445f0d3b3 · 2026-05-21T01:28:29.000+08:00
diff --git a/Source/GUI/Android/app/build.gradle b/Source/GUI/Android/app/build.gradle
@@ -202,7 +202,7 @@ tasks.register('copyLocales', DefaultTask) {
 preBuild.dependsOn copyLocales
 
 dependencies {
-    implementation 'com.google.android.material:material:1.13.0'
+    implementation 'com.google.android.material:material:1.13.0' // can only upgrade when minSdkVersion >= 23
     implementation 'androidx.appcompat:appcompat:1.7.1'
     implementation "androidx.core:core-ktx:1.17.0" // can only upgrade when minSdkVersion >= 23
     implementation 'androidx.documentfile:documentfile:1.1.0'
@@ -215,11 +215,8 @@ dependencies {
     // Android Room
     // can only upgrade when minSdkVersion >= 23
     implementation 'androidx.room:room-runtime:2.7.2'
-    implementation 'androidx.room:room-rxjava2:2.7.2'
+    implementation 'androidx.room:room-ktx:2.7.2'
     ksp 'androidx.room:room-compiler:2.7.2'
-    //RxJava
-    implementation 'io.reactivex.rxjava2:rxjava:2.2.21'
-    implementation 'io.reactivex.rxjava2:rxandroid:2.1.1'
     // Android Lifecycle
     implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
     ksp "androidx.lifecycle:lifecycle-common-java8:2.10.0"
@@ -228,9 +225,7 @@ dependencies {
     implementation "com.android.billingclient:billing:8.0.0"
     implementation "com.android.billingclient:billing-ktx:8.0.0"
     // KotlinX Coroutines
-    api "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.10.2"
-    api "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.10.2"
-    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-rx2:1.10.2"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.11.0"
     // Locales manager
     implementation 'com.github.YarikSOffice:lingver:1.3.0'
 }
diff --git a/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/PagerAdapter.kt b/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/PagerAdapter.kt
@@ -6,24 +6,59 @@
 
 package net.mediaarea.mediainfo
 
-import android.os.Bundle
+// Generated with Google Gemini 3.5 Flash
 
+import android.os.Bundle
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentActivity
+import androidx.recyclerview.widget.DiffUtil
 import androidx.viewpager2.adapter.FragmentStateAdapter
 
-class PagerAdapter(fa: FragmentActivity, private var reports: List<Report>) : FragmentStateAdapter(fa) {
+class PagerAdapter(fa: FragmentActivity) : FragmentStateAdapter(fa) {
+
+    private var reports: List<Report> = emptyList()
+
+    // Explicitly handles item identification across updates
+    override fun getItemId(position: Int): Long {
+        return reports[position].id.toLong() // Critical for stable fragment re-use
+    }
+
+    // Ensures ViewPager2 knows if an item moved or changed
+    override fun containsItem(itemId: Long): Boolean {
+        return reports.any { it.id.toLong() == itemId }
+    }
+
+    // This creates our custom, structurally sound submitList
+    fun submitList(newReports: List<Report>) {
+        val oldReports = this.reports
+
+        val diffResult = DiffUtil.calculateDiff(object : DiffUtil.Callback() {
+            override fun getOldListSize(): Int = oldReports.size
+            override fun getNewListSize(): Int = newReports.size
+
+            override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
+                return oldReports[oldItemPosition].id == newReports[newItemPosition].id
+            }
+
+            override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
+                // Since Report is a data class, this structurally compares all properties
+                return oldReports[oldItemPosition] == newReports[newItemPosition]
+            }
+        })
+
+        this.reports = newReports
+        diffResult.dispatchUpdatesTo(this) // Animates and updates changes beautifully!
+    }
 
     override fun createFragment(position: Int): Fragment {
         return ReportDetailFragment().apply {
             arguments = Bundle().apply {
-                putInt(Core.ARG_REPORT_ID, reports.elementAt(position).id)
+                putInt(Core.ARG_REPORT_ID, reports[position].id)
             }
         }
     }
 
     override fun getItemCount(): Int {
-        return reports.count()
+        return reports.size
     }
-
 }
diff --git a/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/ReportDao.kt b/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/ReportDao.kt
@@ -7,38 +7,37 @@
 package net.mediaarea.mediainfo
 
 import androidx.room.Dao
-import androidx.room.Query
-import androidx.room.Insert
-import androidx.room.Update
 import androidx.room.Delete
+import androidx.room.Insert
 import androidx.room.OnConflictStrategy
-
-import io.reactivex.Flowable
-import io.reactivex.Single
+import androidx.room.Query
+import androidx.room.Update
+import kotlinx.coroutines.flow.Flow
 
 @Dao
 interface ReportDao {
+
     @Query("SELECT MAX(id) FROM reports")
-    fun getLastId(): Single<Int>
+    suspend fun getLastId(): Int?
 
     @Query("SELECT * FROM reports WHERE id = :id")
-    fun getReport(id: Int): Single<Report>
+    suspend fun getReport(id: Int): Report?
 
     @Query("SELECT * FROM reports ORDER BY id")
-    fun getAllReports(): Flowable<List<Report>>
+    fun getAllReports(): Flow<List<Report>>
 
     @Insert(onConflict = OnConflictStrategy.REPLACE)
-    fun insertReport(report: Report)
+    suspend fun insertReport(report: Report): Long
 
     @Update(onConflict = OnConflictStrategy.REPLACE)
-    fun updateReport(report: Report)
+    suspend fun updateReport(report: Report)
 
     @Delete
-    fun deleteReport(report: Report)
+    suspend fun deleteReport(report: Report)
 
     @Query("DELETE FROM reports WHERE id = :id")
-    fun deleteReport(id: Int)
+    suspend fun deleteReport(id: Int)
 
     @Query("DELETE FROM reports")
-    fun deleteAllReports()
+    suspend fun deleteAllReports()
 }
diff --git a/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/ReportDetailActivity.kt b/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/ReportDetailActivity.kt
@@ -13,20 +13,21 @@ import android.content.Intent
 import android.os.Bundle
 import android.os.Build
 
-import android.view.MenuItem
-
 import android.content.res.AssetManager
+import android.view.MenuItem
 import android.view.View
 import androidx.core.view.ViewCompat
 import androidx.core.view.WindowCompat
 import androidx.core.view.WindowInsetsCompat
 import androidx.core.view.updatePadding
-
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.lifecycleScope
+import androidx.lifecycle.repeatOnLifecycle
 import androidx.viewpager2.widget.ViewPager2
 
-import io.reactivex.disposables.CompositeDisposable
-import io.reactivex.schedulers.Schedulers
-import io.reactivex.android.schedulers.AndroidSchedulers
+import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.launch
+
 import net.mediaarea.mediainfo.databinding.ActivityReportDetailBinding
 
 class ReportDetailActivity : AppCompatActivity(), ReportActivityListener {
@@ -40,7 +41,6 @@ class ReportDetailActivity : AppCompatActivity(), ReportActivityListener {
 
         }
     }
-    private val disposable: CompositeDisposable = CompositeDisposable()
     private lateinit var reportModel: ReportViewModel
 
     override fun getReportViewModel(): ReportViewModel {
@@ -96,28 +96,47 @@ class ReportDetailActivity : AppCompatActivity(), ReportActivityListener {
         val viewModelFactory = Injection.provideViewModelFactory(this)
         reportModel = ViewModelProvider(this, viewModelFactory)[ReportViewModel::class.java]
 
-        disposable.add(reportModel.getAllReports()
-            .subscribeOn(Schedulers.io())
-            .observeOn(AndroidSchedulers.mainThread())
-            .subscribe { reports: List<Report> ->
-                activityReportDetailBinding.pager.registerOnPageChangeCallback(PageChangeListener(reports))
-                activityReportDetailBinding.pager.adapter = PagerAdapter(this, reports)
-                val id = intent.getIntExtra(Core.ARG_REPORT_ID, -1)
-                if (id!=-1) {
-                    val index = reports.indexOfFirst { it.id == id }
-                    if (index!=-1) {
-                        title = reports.elementAt(index).filename
-                        activityReportDetailBinding.pager.setCurrentItem(index, false)
+        // From Google Gemini 3.5 Flash
+        // 1. Initialize the adapter ONCE
+        val pagerAdapter = PagerAdapter(this)
+        activityReportDetailBinding.pager.adapter = pagerAdapter
+        // 2. Track your active listener reference locally
+        var pageChangeListener: ViewPager2.OnPageChangeCallback? = null
+        // 3. Collect data changes safely inside the single lifecycle coroutine
+        lifecycleScope.launch {
+            repeatOnLifecycle(Lifecycle.State.STARTED) {
+                // We use a flag to track if we have already run the initial intent-navigation jump
+                var isInitialSetupDone = false
+                reportModel.getAllReports().collectLatest { reports: List<Report> ->
+                    // A. Update the listener with the fresh data list safely without adding a new callback instance
+                    pageChangeListener?.let { oldListener ->
+                        activityReportDetailBinding.pager.unregisterOnPageChangeCallback(oldListener)
+                    }
+                    pageChangeListener = PageChangeListener(reports)
+                    activityReportDetailBinding.pager.registerOnPageChangeCallback(pageChangeListener)
+                    // B. Push the new items cleanly into your existing adapter
+                    pagerAdapter.submitList(reports)
+                    // C. Handle the intent navigation token EXACTLY ONCE on initial load
+                    if (!isInitialSetupDone) {
+                        val targetId = intent.getIntExtra(Core.ARG_REPORT_ID, -1)
+                        if (targetId != -1) {
+                            val index = reports.indexOfFirst { it.id == targetId }
+                            if (index != -1) {
+                                title = reports[index].filename
+                                activityReportDetailBinding.pager.setCurrentItem(index, false)
+                            }
+                        }
+                        isInitialSetupDone = true // Lock it so subsequent DB updates don't snap the user back
+                    } else {
+                        // Update the title dynamically based on the current visible item during background updates
+                        val currentIndex = activityReportDetailBinding.pager.currentItem
+                        if (currentIndex in reports.indices) {
+                            title = reports[currentIndex].filename
+                        }
                     }
                 }
-            })
-    }
-
-    override fun onStop() {
-        super.onStop()
-
-        // clear all the subscription
-        disposable.clear()
+            }
+        }
     }
 
     override fun finish() {
diff --git a/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/ReportDetailFragment.kt b/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/ReportDetailFragment.kt
@@ -17,6 +17,7 @@ import androidx.core.view.MenuProvider
 import androidx.documentfile.provider.DocumentFile
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.lifecycleScope
 import androidx.preference.PreferenceManager.getDefaultSharedPreferences
 
 import android.os.Bundle
@@ -25,15 +26,14 @@ import android.content.Context
 import android.view.*
 import android.widget.Toast
 
-import io.reactivex.android.schedulers.AndroidSchedulers
-import io.reactivex.disposables.CompositeDisposable
-import io.reactivex.schedulers.Schedulers
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 
 import net.mediaarea.mediainfo.databinding.ReportDetailBinding
 
 
 class ReportDetailFragment : Fragment() {
-    private val disposable: CompositeDisposable = CompositeDisposable()
     private lateinit var activityListener: ReportActivityListener
     private var sharedPreferences: SharedPreferences? = null
     private lateinit var reportDetailBinding: ReportDetailBinding
@@ -52,32 +52,31 @@ class ReportDetailFragment : Fragment() {
                 return@let
             }
 
-            disposable
-                .add(activityListener.getReportViewModel().getReport(it)
-                    .subscribeOn(Schedulers.io())
-                    .observeOn(AndroidSchedulers.mainThread())
-                    .subscribe { report: Report ->
-                        if (report.report.isEmpty()) {
+            lifecycleScope.launch {
+                withContext(Dispatchers.IO) {
+                    val report = activityListener.getReportViewModel().getReport(it)
+                    if (report == null || report.report.isEmpty()) {
+                        onError()
+                    } else {
+                        val currentContext: Context? = context
+                        if (currentContext == null) {
                             onError()
                         } else {
-                            val currentContext: Context? = context
-                            if (currentContext == null) {
+                            val directory = DocumentFile.fromTreeUri(currentContext, uri)
+
+                            if (directory == null) {
                                 onError()
                             } else {
-                                val directory = DocumentFile.fromTreeUri(currentContext, uri)
-
-                                if (directory == null) {
+                                if (!directory.canWrite()) {
                                     onError()
                                 } else {
-                                    if (!directory.canWrite()) {
-                                        onError()
-                                    } else {
-                                        saveReport(directory, report)
-                                    }
+                                    saveReport(directory, report)
                                 }
                             }
                         }
-                    })
+                    }
+                }
+            }
         }
     }
 
@@ -120,36 +119,30 @@ class ReportDetailFragment : Fragment() {
         }
     }
 
-    override fun onStop() {
-        super.onStop()
-
-        // clear all the subscription
-        disposable.clear()
-    }
-
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                               savedInstanceState: Bundle?): View {
 
         //val rootView = inflater.inflate(R.layout.report_detail, container, false)
         // Show the report
         id?.let { id ->
-            disposable.add(activityListener.getReportViewModel().getReport(id)
-                    .subscribeOn(Schedulers.io())
-                    .observeOn(AndroidSchedulers.mainThread())
-                    .doOnSuccess {
-                        val report: String = Core.convertReport(it.report, view)
-                        var content = ""
-                        if (view != "HTML") {
-                            content += "<html><head>" +
-                                    "<style>:root { color-scheme: var(--color-scheme, light); } @media (prefers-color-scheme: dark) { :root { --color-scheme: dark; } }</style>" +
-                                    "</head><body><pre>"
-                            content += report.replace("\t", "    ").htmlEncode()
-                            content += "</pre></body></html>"
-                        } else {
-                            content+=report
-                        }
-                        reportDetailBinding.reportDetail.loadDataWithBaseURL(null, content, "text/html", "utf-8", null)
-             }.subscribe())
+            lifecycleScope.launch {
+                val content = withContext(Dispatchers.IO) {
+                    val reportObject = activityListener.getReportViewModel().getReport(id)
+                    val report: String = if (reportObject != null ) Core.convertReport(reportObject.report, view) else "Error fetching report."
+                    var content = ""
+                    if (view != "HTML") {
+                        content += "<html><head>" +
+                                "<style>:root { color-scheme: var(--color-scheme, light); } @media (prefers-color-scheme: dark) { :root { --color-scheme: dark; } }</style>" +
+                                "</head><body><pre>"
+                        content += report.replace("\t", "    ").htmlEncode()
+                        content += "</pre></body></html>"
+                    } else {
+                        content+=report
+                    }
+                    content
+                }
+                reportDetailBinding.reportDetail.loadDataWithBaseURL(null, content, "text/html", "utf-8", null)
+             }
         }
 
         return reportDetailBinding.root
diff --git a/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/ReportListActivity.kt b/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/ReportListActivity.kt
diff --git a/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/ReportViewModel.kt b/Source/GUI/Android/app/src/main/java/net/mediaarea/mediainfo/ReportViewModel.kt
