[FIXED] Using navigator pattern to clean up the activity.

app/src/main/java/com/hossainkhan/android/demo/browse/DefaultLayoutBrowseNavigator.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2019 Hossain Khan
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hossainkhan.android.demo.browse
+
+import android.content.Context
+import android.content.Intent
+import com.hossainkhan.android.demo.layoutpreview.LayoutPreviewBaseActivity
+import javax.inject.Inject
+
+class DefaultLayoutBrowseNavigator @Inject constructor(private val context: Context) : LayoutBrowseNavigator {
+    override fun loadLayoutPreview(layoutResId: Int) {
+        val startIntent = LayoutPreviewBaseActivity.createStartIntent(context, layoutResId)
+        // FIX IT: android.util.AndroidRuntimeException: Calling startActivity() from outside of an Activity  context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?
+        startIntent.flags = Intent.FLAG_ACTIVITY_NEW_TASK
+        context.startActivity(startIntent)
+    }
+
+    override fun <T> loadLayoutPreview(clazz: Class<T>, layoutResId: Int) {
+        val startIntent = LayoutPreviewBaseActivity.createStartIntent(context, clazz, layoutResId)
+        // FIX IT: android.util.AndroidRuntimeException: Calling startActivity() from outside of an Activity  context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?
+        startIntent.flags = Intent.FLAG_ACTIVITY_NEW_TASK
+        context.startActivity(startIntent)
+    }
+}

app/src/main/java/com/hossainkhan/android/demo/browse/LayoutBrowseActivity.kt

@@ -22,14 +22,8 @@ import androidx.lifecycle.ViewModelProviders
 import androidx.recyclerview.widget.GridLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import com.hossainkhan.android.demo.R
-import com.hossainkhan.android.demo.layoutpreview.LayoutChainStyleActivity
-import com.hossainkhan.android.demo.layoutpreview.LayoutGuidelineBarrierActivity
-import com.hossainkhan.android.demo.layoutpreview.LayoutGuidelineGroupActivity
-import com.hossainkhan.android.demo.layoutpreview.LayoutPreviewBaseActivity
-import com.hossainkhan.android.demo.layoutpreview.LayoutVisibilityGoneActivity
 import com.hossainkhan.android.demo.viewmodel.LayoutPreviewViewModelFactory
 import dagger.android.AndroidInjection
-import timber.log.Timber
 import javax.inject.Inject
 
 /**
@@ -61,7 +55,7 @@ class LayoutBrowseActivity : AppCompatActivity() {
         viewAdapter = LayoutBrowseAdapter(
                 viewModel = viewModel,
                 lifecycleOwner = this,
-                itemSelectedListener = this::onLayoutItemSelected)
+                itemSelectedListener = viewModel::onLayoutItemSelected)
 
         recyclerView = findViewById<RecyclerView>(R.id.recycler_view).apply {
             // use this setting to improve performance if you know that changes
@@ -75,35 +69,4 @@ class LayoutBrowseActivity : AppCompatActivity() {
             adapter = viewAdapter
         }
     }
-
-    private fun onLayoutItemSelected(layoutResId: Int) {
-        Timber.i("Selected layout id: %s", layoutResId)
-
-        /*
-         * Where applicable, loads specific activity with interactive feature for user to try out feature.
-         */
-        when (layoutResId) {
-            R.layout.preview_visibility_gone -> {
-                startActivity(LayoutPreviewBaseActivity.createStartIntent(this,
-                        LayoutVisibilityGoneActivity::class.java, R.layout.preview_visibility_gone))
-            }
-            R.layout.preview_chain_style_main -> {
-                startActivity(LayoutPreviewBaseActivity.createStartIntent(this,
-                        LayoutChainStyleActivity::class.java, R.layout.preview_chain_style_main))
-            }
-            R.layout.preview_virtual_helper_barrier -> {
-                startActivity(LayoutPreviewBaseActivity.createStartIntent(this,
-                        LayoutGuidelineBarrierActivity::class.java, R.layout.preview_virtual_helper_barrier))
-            }
-            R.layout.preview_virtual_helper_group -> {
-                startActivity(LayoutPreviewBaseActivity.createStartIntent(this,
-                        LayoutGuidelineGroupActivity::class.java, R.layout.preview_virtual_helper_group))
-            }
-            else -> {
-                // By default it loads the preview activity with the layout requested.
-                startActivity(LayoutPreviewBaseActivity.createStartIntent(this, layoutResId))
-            }
-        }
-
-    }
 }

app/src/main/java/com/hossainkhan/android/demo/browse/LayoutBrowseNavigator.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2019 Hossain Khan
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hossainkhan.android.demo.browse
+
+import androidx.annotation.LayoutRes
+
+/**
+ * Interface to navigate for Layout Browse view.
+ */
+interface LayoutBrowseNavigator {
+    fun loadLayoutPreview(@LayoutRes layoutResId: Int)
+    fun <T> loadLayoutPreview(clazz: Class<T>, @LayoutRes layoutResId: Int)
+}

app/src/main/java/com/hossainkhan/android/demo/browse/LayoutBrowseViewModel.kt

@@ -19,23 +19,57 @@ package com.hossainkhan.android.demo.browse
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
+import com.hossainkhan.android.demo.R
 import com.hossainkhan.android.demo.data.AppDataStore
 import com.hossainkhan.android.demo.data.LayoutInformation
+import com.hossainkhan.android.demo.layoutpreview.LayoutChainStyleActivity
+import com.hossainkhan.android.demo.layoutpreview.LayoutGuidelineBarrierActivity
+import com.hossainkhan.android.demo.layoutpreview.LayoutGuidelineGroupActivity
+import com.hossainkhan.android.demo.layoutpreview.LayoutVisibilityGoneActivity
 import timber.log.Timber
 
 class LayoutBrowseViewModel(
-        appDataStore: AppDataStore) : ViewModel() {
+        appDataStore: AppDataStore,
+        private val browseNavigator: LayoutBrowseNavigator) : ViewModel() {
 
     private val layoutInfoListLiveData = MutableLiveData<List<LayoutInformation>>()
 
     val layoutInfos: LiveData<List<LayoutInformation>>
         get() = layoutInfoListLiveData
 
     init {
-        Timber.d("Got data: ${appDataStore.isFirstTime()}")
+        Timber.d("Is first time user: ${appDataStore.isFirstTime()}")
         appDataStore.updateFirstTimeUser(false)
 
 
         layoutInfoListLiveData.value = appDataStore.layoutStore.supportedLayoutInfos
     }
+
+
+    fun onLayoutItemSelected(layoutResId: Int) {
+        Timber.i("Selected layout id: %s", layoutResId)
+
+        /*
+         * Where applicable, loads specific activity with interactive feature for user to try out feature.
+         */
+        when (layoutResId) {
+            R.layout.preview_visibility_gone -> {
+                browseNavigator.loadLayoutPreview(LayoutVisibilityGoneActivity::class.java, layoutResId)
+            }
+            R.layout.preview_chain_style_main -> {
+                browseNavigator.loadLayoutPreview(LayoutChainStyleActivity::class.java, layoutResId)
+            }
+            R.layout.preview_virtual_helper_barrier -> {
+                browseNavigator.loadLayoutPreview(LayoutGuidelineBarrierActivity::class.java, layoutResId)
+            }
+            R.layout.preview_virtual_helper_group -> {
+                browseNavigator.loadLayoutPreview(LayoutGuidelineGroupActivity::class.java, layoutResId)
+            }
+            else -> {
+                // By default it loads the preview activity with the layout requested.
+                browseNavigator.loadLayoutPreview(layoutResId)
+            }
+        }
+
+    }
 }

app/src/main/java/com/hossainkhan/android/demo/dagger/ActivityBindingModule.kt

@@ -16,6 +16,7 @@
 
 package com.hossainkhan.android.demo.dagger
 
+import com.hossainkhan.android.demo.browse.LayoutBrowseActivity
 import com.hossainkhan.android.demo.layoutpreview.LayoutChainStyleActivity
 import com.hossainkhan.android.demo.layoutpreview.LayoutGuidelineBarrierActivity
 import com.hossainkhan.android.demo.layoutpreview.LayoutGuidelineGroupActivity
@@ -48,9 +49,10 @@ abstract class ActivityBindingModule {
      * into the subcomponent. If the subcomponent needs scopes, apply the scope annotations to
      * the method as well.
      */
+
     @ActivityScope
     @ContributesAndroidInjector
-    abstract fun layoutPositioningActivity(): LayoutPreviewBaseActivity
+    abstract fun layoutPreviewBaseActivity(): LayoutPreviewBaseActivity
 
     @ActivityScope
     @ContributesAndroidInjector

app/src/main/java/com/hossainkhan/android/demo/dagger/DemoApplicationComponent.kt

@@ -27,7 +27,8 @@ import javax.inject.Singleton
         ApplicationModule::class,
         ActivityBindingModule::class,
         DataStoreModule::class,
-        MainActivityModule::class))
+        NavigatorModule::class,
+        LayoutBrowseActivityModule::class))
 interface DemoApplicationComponent {
     fun inject(app: DemoApplication)
 

app/src/main/java/com/hossainkhan/android/demo/dagger/MainActivityModule.kt → app/src/main/java/com/hossainkhan/android/demo/dagger/LayoutBrowseActivityModule.kt

@@ -24,13 +24,13 @@ import dagger.android.ActivityKey
 import dagger.android.AndroidInjector
 import dagger.multibindings.IntoMap
 
-@Module(subcomponents = arrayOf(MainActivitySubcomponent::class))
-abstract class MainActivityModule {
+@Module(subcomponents = [LayoutBrowseSubcomponent::class])
+abstract class LayoutBrowseActivityModule {
 
     @Binds
     @IntoMap
     @ActivityKey(LayoutBrowseActivity::class)
     abstract fun bindMainActivityInjectorFactory(
-            builder: MainActivitySubcomponent.Builder): AndroidInjector.Factory<out Activity>
+            builder: LayoutBrowseSubcomponent.Builder): AndroidInjector.Factory<out Activity>
 
 }

app/src/main/java/com/hossainkhan/android/demo/dagger/MainActivitySubcomponent.kt → app/src/main/java/com/hossainkhan/android/demo/dagger/LayoutBrowseSubcomponent.kt

@@ -21,7 +21,7 @@ import dagger.Subcomponent
 import dagger.android.AndroidInjector
 
 @Subcomponent
-interface MainActivitySubcomponent : AndroidInjector<LayoutBrowseActivity> {
+interface LayoutBrowseSubcomponent : AndroidInjector<LayoutBrowseActivity> {
     @Subcomponent.Builder
     abstract class Builder : AndroidInjector.Builder<LayoutBrowseActivity>()
 }

app/src/main/java/com/hossainkhan/android/demo/dagger/NavigatorModule.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2019 Hossain Khan
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hossainkhan.android.demo.dagger
+
+import android.content.Context
+import com.hossainkhan.android.demo.browse.DefaultLayoutBrowseNavigator
+import com.hossainkhan.android.demo.browse.LayoutBrowseNavigator
+import dagger.Module
+import dagger.Provides
+
+@Module
+class NavigatorModule {
+
+    @Provides
+    fun provideLayoutBrowseNavigator(context: Context): LayoutBrowseNavigator {
+        return DefaultLayoutBrowseNavigator(context)
+    }
+}

app/src/main/java/com/hossainkhan/android/demo/viewmodel/LayoutPreviewViewModelFactory.kt

@@ -18,6 +18,7 @@ package com.hossainkhan.android.demo.viewmodel
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
+import com.hossainkhan.android.demo.browse.LayoutBrowseNavigator
 import com.hossainkhan.android.demo.browse.LayoutBrowseViewModel
 import com.hossainkhan.android.demo.data.AppDataStore
 import com.hossainkhan.android.demo.layoutpreview.LayoutInfoViewModel
@@ -27,7 +28,8 @@ import javax.inject.Inject
  * The [ViewModelProvider.Factory] that provides all the ViewModels for the activities and fragments.
  */
 class LayoutPreviewViewModelFactory @Inject constructor(
-        private val dataStore: AppDataStore
+        private val dataStore: AppDataStore,
+        private val browseNavigator: LayoutBrowseNavigator
 
 ) : ViewModelProvider.Factory {
     @Suppress("UNCHECKED_CAST")
@@ -37,7 +39,7 @@ class LayoutPreviewViewModelFactory @Inject constructor(
                 LayoutInfoViewModel(dataStore) as T
             }
             modelClass.isAssignableFrom(LayoutBrowseViewModel::class.java) -> {
-                LayoutBrowseViewModel(dataStore) as T
+                LayoutBrowseViewModel(dataStore,browseNavigator) as T
             }
             else -> throw IllegalArgumentException("Unknown ViewModel class")
         }