Verified working in API Level 21

- Newer (than 2.13.x) versions of jackson does not work on API level < 26 in android
  FasterXML/jackson-databind#3702
- Unlinked LettersTabViewModel and Transliterator instantiation
  Transliterator instantiation now uses fragment context instead of
  application context
- Removed unused references to previously tested progress bar

Author: NyxTrail

app/build.gradle

@@ -61,14 +61,16 @@ dependencies {
     implementation 'com.google.android.material:material:1.7.0'
     implementation 'androidx.preference:preference:1.2.0'
     implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
-    implementation 'androidx.fragment:fragment:1.5.4'
+    implementation 'androidx.fragment:fragment:1.5.5'
     implementation 'androidx.legacy:legacy-support-v4:1.0.0'
     implementation 'androidx.gridlayout:gridlayout:1.0.0'
     implementation 'androidx.window:window:1.0.0'
     implementation 'androidx.annotation:annotation:1.5.0'
     implementation 'com.squareup.retrofit2:retrofit:2.9.0'
-    implementation 'com.fasterxml.jackson.core:jackson-databind:2.14.0'
-    implementation 'com.fasterxml.jackson.module:jackson-module-kotlin:2.14.0'
+    // Newer (than 2.13.x) versions of jackson does not work on API level < 26 in android
+    // https://github.com/FasterXML/jackson-databind/issues/3702
+    implementation 'com.fasterxml.jackson.core:jackson-databind:2.13.4'
+    implementation 'com.fasterxml.jackson.module:jackson-module-kotlin:2.13.4'
     implementation 'androidx.navigation:navigation-fragment-ktx:2.5.3'
     implementation 'androidx.navigation:navigation-ui-ktx:2.5.3'
     implementation 'androidx.core:core-ktx:1.9.0'

app/src/main/kotlin/in/digistorm/aksharam/activities/main/letters/LettersTabFragment.kt

@@ -29,7 +29,6 @@ import android.widget.*
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.viewModels
 import androidx.recyclerview.widget.RecyclerView
-import com.google.android.material.progressindicator.LinearProgressIndicator
 import com.google.android.material.textfield.MaterialAutoCompleteTextView
 import com.google.android.material.textfield.TextInputLayout
 import kotlin.collections.ArrayList
@@ -68,7 +67,9 @@ class LettersTabFragment: Fragment() {
         super.onViewCreated(view, savedInstanceState)
         logDebug(logTag, "onViewCreated")
 
-        logDebug(logTag, "Letters category wise: ${viewModel.transliterator.languageData.lettersCategoryWise}")
+        // Initialise the transliterator
+        viewModel.transliterator = Transliterator(requireContext())
+        logDebug(logTag, "Letters category wise: ${viewModel.transliterator!!.languageData.lettersCategoryWise}")
         letterCategoryListView = view.findViewById(R.id.letter_categories)!!
         languageSelector = view.findViewById(R.id.language_selector)
         convertToSelector = view.findViewById(R.id.convert_to_selector)
@@ -80,8 +81,9 @@ class LettersTabFragment: Fragment() {
         view.findViewById<View>(R.id.lettersTabInfoButton).setOnClickListener { v: View? ->
             logDebug(logTag, "Info button clicked!")
             logDebug(logTag,
-                "Fetching info for transliterating ${viewModel.transliterator.languageData.language} to ${viewModel.targetLanguage}")
-            val info: HashMap<String, Map<String, String>> = viewModel.transliterator.languageData.info
+                "Fetching info for transliterating ${viewModel.transliterator!!.languageData.language} " +
+                        "to ${viewModel.targetLanguage}")
+            val info: HashMap<String, Map<String, String>> = viewModel.transliterator!!.languageData.info
             logDebug(logTag, "Data for info: $info")
             val lif = LanguageInfoFragment.newInstance(
                 info["general"]?.get("en") + info[viewModel.targetLanguage.lowercase()]?.get("en"))
@@ -90,15 +92,14 @@ class LettersTabFragment: Fragment() {
 
         val categoryListViewAdapter = LetterCategoryAdapter(
             viewModel.getLanguageData().lettersCategoryWise,
-            viewModel.transliterator,
+            viewModel.transliterator!!,
             viewModel.targetLanguage,
         )
         letterCategoryListView.adapter = categoryListViewAdapter
-        categoryListViewAdapter.submitList(viewModel.transliterator.languageData.categories)
+        categoryListViewAdapter.submitList(viewModel.transliterator!!.languageData.categories)
 
         logDebug(logTag, "Setting up observers for view model data")
         initObservers(view)
-        view.findViewById<LinearProgressIndicator>(R.id.progress_indicator).visibility = View.GONE
     }
 
     // Return an empty array list if we could not find any
@@ -123,7 +124,7 @@ class LettersTabFragment: Fragment() {
         languageListAdapter.setNotifyOnChange(true)
 
         languageTextView?.setAdapter(languageListAdapter)
-        val upperCasedLanguage = viewModel.transliterator.getLanguage().replaceFirstChar {
+        val upperCasedLanguage = viewModel.transliterator!!.getLanguage().replaceFirstChar {
             if (it.isLowerCase())
                 it.titlecase()
             else
@@ -215,7 +216,7 @@ class LettersTabFragment: Fragment() {
             (letterCategoryListView.adapter as LetterCategoryAdapter).apply {
                 setLettersCategoryWise(viewModel.getLanguageData().lettersCategoryWise)
                 updateTargetLanguage(viewModel.targetLanguage)
-                updateTransliterator(viewModel.transliterator)
+                updateTransliterator(viewModel.transliterator!!)
                 logDebug(logTag, "LetterCategoryAdapter Inspection: \n" +
                         "Item count: ${itemCount} \n" +
                         "Current List: ${currentList}")
@@ -240,7 +241,5 @@ class LettersTabFragment: Fragment() {
                 adapter.updateLetterGrids(letterCategoryListView)
             }
         }
-
-
     }
 }

app/src/main/kotlin/in/digistorm/aksharam/activities/main/letters/LettersTabViewModel.kt

@@ -31,7 +31,7 @@ import androidx.lifecycle.MutableLiveData
 class LettersTabViewModel(application: Application): AndroidViewModel(application) {
     private val logTag = javaClass.simpleName
 
-    var transliterator: Transliterator = Transliterator(application)
+    var transliterator: Transliterator? = null
 
     // The current language displayed in letters tab
     var languageLiveData: MutableLiveData<String> = MutableLiveData()
@@ -54,18 +54,14 @@ class LettersTabViewModel(application: Application): AndroidViewModel(applicatio
             targetLanguageLiveData.value = value
         }
 
-    init {
-        // language = transliterator.getLanguage()
-    }
-
     // Set the transliterator based on a specific language
     fun setTransliterator(language: String, context: Context) {
-        if (transliterator.getLanguage().lowercase() != language.lowercase())
+        if (transliterator!!.getLanguage().lowercase() != language.lowercase())
             transliterator = Transliterator(language, context)
     }
 
     // A convenience method to obtain language data
     fun getLanguageData(): Language {
-        return transliterator.languageData
+        return transliterator!!.languageData
     }
 }

app/src/main/kotlin/in/digistorm/aksharam/activities/main/practice/InputTextChangedListener.kt

@@ -17,7 +17,7 @@ class InputTextChangedListener(
 
     private val viewModel: PracticeTabViewModel by practiceTabFragment.viewModels()
     private val practiceTextTV: TextView = practiceTabFragment.requireView()
-        .requireViewById(R.id.PracticeTabPracticeTextTV)
+        .findViewById(R.id.PracticeTabPracticeTextTV)!!
 
     override fun afterTextChanged(s: Editable) {}
     override fun beforeTextChanged(s: CharSequence, start: Int, count: Int, after: Int) {}

app/src/main/kotlin/in/digistorm/aksharam/util/Transliterator.kt

@@ -23,7 +23,6 @@ import android.content.Context
 import android.content.Intent
 import java.lang.StringBuilder
 import `in`.digistorm.aksharam.activities.initialise.InitialiseAppActivity
-import kotlin.math.log
 
 // This class is responsible for the actual transliteration
 class Transliterator {