ToDoDatabase singleton updated/fixed.

navHostFragment's layout width and height are now 0dp (match constraint)

app/build.gradle

@@ -5,13 +5,13 @@ apply plugin: 'kotlin-kapt'
 apply plugin: "androidx.navigation.safeargs.kotlin"
 
 android {
-    compileSdkVersion 29
+    compileSdkVersion 30
     buildToolsVersion "30.0.0"
 
     defaultConfig {
         applicationId "com.example.todoapp"
         minSdkVersion 26
-        targetSdkVersion 29
+        targetSdkVersion 30
         versionCode 1
         versionName "1.0"
 
@@ -42,8 +42,8 @@ android {
 dependencies {
     implementation fileTree(dir: "libs", include: ["*.jar"])
     implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
-    implementation 'androidx.core:core-ktx:1.3.0'
-    implementation 'androidx.appcompat:appcompat:1.1.0'
+    implementation 'androidx.core:core-ktx:1.3.1'
+    implementation 'androidx.appcompat:appcompat:1.2.0'
     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
     implementation 'androidx.legacy:legacy-support-v4:1.0.0'
     testImplementation 'junit:junit:4.13'
@@ -67,12 +67,12 @@ dependencies {
 
     // Kotlin components
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.72"
-    api "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.5"
-    api "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.5"
+    api "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.7"
+    api "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.7"
 
     // DataBinding
     kapt "com.android.databinding:compiler:3.2.0-alpha10"
-    kapt "androidx.databinding:databinding-common:4.0.0"
+    kapt "androidx.databinding:databinding-common:4.0.1"
 
     // RecyclerView Animator
     implementation 'jp.wasabeef:recyclerview-animators:3.0.0'

app/src/main/java/com/example/todoapp/data/ToDoDatabase.kt

@@ -9,29 +9,47 @@ import com.example.todoapp.data.models.ToDoData
 
 @Database(entities = [ToDoData::class], version = 1, exportSchema = false)
 @TypeConverters(Converter::class)
-abstract class ToDoDatabase: RoomDatabase() {
+abstract class ToDoDatabase : RoomDatabase() {
 
     abstract fun toDoDao(): ToDoDao
 
+//    companion object {
+//        @Volatile
+//        private var INSTANCE: ToDoDatabase? = null
+//
+//        fun getDatabase(context: Context): ToDoDatabase {
+//            val tempInstance = INSTANCE
+//            if (tempInstance != null) {
+//                return tempInstance
+//            }
+//            synchronized(this) {
+//                val instance = Room.databaseBuilder(
+//                    context.applicationContext,
+//                    ToDoDatabase::class.java,
+//                    "todo_database"
+//                ).build()
+//                INSTANCE = instance
+//                return instance
+//            }
+//        }
+//    }
+
     companion object {
         @Volatile
         private var INSTANCE: ToDoDatabase? = null
 
-        fun getDatabase(context: Context): ToDoDatabase {
-            val tempInstance = INSTANCE
-            if(tempInstance != null){
-                return tempInstance
+        fun getDatabase(context: Context): ToDoDatabase =
+            INSTANCE ?: synchronized(this) {
+                INSTANCE
+                    ?: buildDatabase(context).also { INSTANCE = it }
             }
-            synchronized(this){
-                val instance = Room.databaseBuilder(
+
+        private fun buildDatabase(context: Context) =
+            Room.databaseBuilder(
                 context.applicationContext,
-                    ToDoDatabase::class.java,
-                    "todo_database"
-                ).build()
-                INSTANCE = instance
-                return instance
-            }
-        }
+                ToDoDatabase::class.java, "todo_database"
+            )
+                .build()
     }
 
 }

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

@@ -9,8 +9,8 @@
     <fragment
         android:id="@+id/navHostFragment"
         android:name="androidx.navigation.fragment.NavHostFragment"
-        android:layout_width="409dp"
-        android:layout_height="729dp"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
         app:defaultNavHost="true"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"