create a MyFragment parent class

app/src/main/kotlin/com/simplemobiletools/launcher/activities/MainActivity.kt

@@ -15,6 +15,7 @@ import com.simplemobiletools.commons.extensions.*
 import com.simplemobiletools.launcher.BuildConfig
 import com.simplemobiletools.launcher.R
 import com.simplemobiletools.launcher.fragments.AllAppsFragment
+import com.simplemobiletools.launcher.fragments.MyFragment
 import com.simplemobiletools.launcher.interfaces.FlingListener
 import kotlinx.android.synthetic.main.activity_main.*
 
@@ -35,11 +36,14 @@ class MainActivity : SimpleActivity(), FlingListener {
 
         mDetector = GestureDetectorCompat(this, MyGestureListener(this))
         window.setDecorFitsSystemWindows(false)
-        (all_apps_fragment as AllAppsFragment).setupFragment(this)
         mScreenHeight = realScreenSize.y
         mCurrentFragmentY = mScreenHeight
-        all_apps_fragment.y = mScreenHeight.toFloat()
-        all_apps_fragment.beVisible()
+
+        arrayOf(all_apps_fragment as MyFragment, widgets_fragment as MyFragment).forEach { fragment ->
+            fragment.setupFragment(this)
+            fragment.y = mScreenHeight.toFloat()
+            fragment.beVisible()
+        }
     }
 
     override fun onResume() {
@@ -75,9 +79,9 @@ class MainActivity : SimpleActivity(), FlingListener {
                 mTouchDownY = -1
                 if (!mIgnoreUpEvent) {
                     if (all_apps_fragment.y < mScreenHeight * 0.7) {
-                        showAllAppsFragment()
+                        showAllAppsFragment(all_apps_fragment as MyFragment)
                     } else {
-                        hideAllAppsFragment()
+                        hideAllAppsFragment(all_apps_fragment as MyFragment)
                     }
                 }
             }
@@ -92,15 +96,15 @@ class MainActivity : SimpleActivity(), FlingListener {
         mIgnoreUpEvent = false
     }
 
-    private fun showAllAppsFragment() {
-        ObjectAnimator.ofFloat(all_apps_fragment, "y", 0f).apply {
+    private fun showAllAppsFragment(fragment: MyFragment) {
+        ObjectAnimator.ofFloat(fragment, "y", 0f).apply {
             interpolator = DecelerateInterpolator()
             start()
         }
     }
 
-    private fun hideAllAppsFragment() {
-        ObjectAnimator.ofFloat(all_apps_fragment, "y", mScreenHeight.toFloat()).apply {
+    private fun hideAllAppsFragment(fragment: MyFragment) {
+        ObjectAnimator.ofFloat(fragment, "y", mScreenHeight.toFloat()).apply {
             interpolator = DecelerateInterpolator()
             start()
         }
@@ -147,11 +151,11 @@ class MainActivity : SimpleActivity(), FlingListener {
 
     override fun onFlingUp() {
         mIgnoreUpEvent = true
-        showAllAppsFragment()
+        showAllAppsFragment(all_apps_fragment as MyFragment)
     }
 
     override fun onFlingDown() {
         mIgnoreUpEvent = true
-        hideAllAppsFragment()
+        hideAllAppsFragment(all_apps_fragment as MyFragment)
     }
 }

app/src/main/kotlin/com/simplemobiletools/launcher/fragments/AllAppsFragment.kt

@@ -11,7 +11,6 @@ import android.util.AttributeSet
 import android.view.MotionEvent
 import android.view.Surface
 import android.view.WindowManager
-import android.widget.RelativeLayout
 import com.simplemobiletools.commons.extensions.*
 import com.simplemobiletools.commons.helpers.ensureBackgroundThread
 import com.simplemobiletools.commons.helpers.isRPlus
@@ -23,12 +22,11 @@ import com.simplemobiletools.launcher.extensions.getColumnCount
 import com.simplemobiletools.launcher.models.AppLauncher
 import kotlinx.android.synthetic.main.all_apps_fragment.view.*
 
-class AllAppsFragment(context: Context, attributeSet: AttributeSet) : RelativeLayout(context, attributeSet) {
+class AllAppsFragment(context: Context, attributeSet: AttributeSet) : MyFragment(context, attributeSet) {
     private var touchDownY = -1
-    private var activity: MainActivity? = null
 
     @SuppressLint("ClickableViewAccessibility")
-    fun setupFragment(activity: MainActivity) {
+    override fun setupFragment(activity: MainActivity) {
         this.activity = activity
         background.applyColorFilter(activity.getProperBackgroundColor())
         setPadding(0, activity.statusBarHeight, 0, 0)

app/src/main/kotlin/com/simplemobiletools/launcher/fragments/MyFragment.kt

@@ -0,0 +1,12 @@
+package com.simplemobiletools.launcher.fragments
+
+import android.content.Context
+import android.util.AttributeSet
+import android.widget.RelativeLayout
+import com.simplemobiletools.launcher.activities.MainActivity
+
+abstract class MyFragment(context: Context, attributeSet: AttributeSet) : RelativeLayout(context, attributeSet) {
+    protected var activity: MainActivity? = null
+
+    abstract fun setupFragment(activity: MainActivity)
+}

app/src/main/kotlin/com/simplemobiletools/launcher/fragments/WidgetsFragment.kt

@@ -3,7 +3,6 @@ package com.simplemobiletools.launcher.fragments
 import android.appwidget.AppWidgetManager
 import android.content.Context
 import android.util.AttributeSet
-import android.widget.RelativeLayout
 import com.simplemobiletools.commons.extensions.applyColorFilter
 import com.simplemobiletools.commons.extensions.getProperBackgroundColor
 import com.simplemobiletools.commons.extensions.statusBarHeight
@@ -11,10 +10,8 @@ import com.simplemobiletools.commons.helpers.ensureBackgroundThread
 import com.simplemobiletools.launcher.activities.MainActivity
 import com.simplemobiletools.launcher.models.AppWidget
 
-class WidgetsFragment(context: Context, attributeSet: AttributeSet) : RelativeLayout(context, attributeSet) {
-    private var activity: MainActivity? = null
-
-    fun setupFragment(activity: MainActivity) {
+class WidgetsFragment(context: Context, attributeSet: AttributeSet) : MyFragment(context, attributeSet) {
+    override fun setupFragment(activity: MainActivity) {
         this.activity = activity
         background.applyColorFilter(activity.getProperBackgroundColor())
         setPadding(0, activity.statusBarHeight, 0, 0)

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

@@ -9,6 +9,11 @@
         layout="@layout/all_apps_fragment"
         android:visibility="gone" />
 
+    <include
+        android:id="@+id/widgets_fragment"
+        layout="@layout/widgets_fragment"
+        android:visibility="gone" />
+
     <View
         android:id="@+id/popup_menu_anchor"
         android:layout_width="1dp"

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

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<com.simplemobiletools.launcher.fragments.AllAppsFragment xmlns:android="http://schemas.android.com/apk/res/android"
+<com.simplemobiletools.launcher.fragments.WidgetsFragment xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:id="@+id/widgets_holder"
     android:layout_width="match_parent"
@@ -20,4 +20,4 @@
             app:layoutManager="com.simplemobiletools.commons.views.MyLinearLayoutManager" />
 
     </com.qtalk.recyclerviewfastscroller.RecyclerViewFastScroller>
-</com.simplemobiletools.launcher.fragments.AllAppsFragment>
+</com.simplemobiletools.launcher.fragments.WidgetsFragment>