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FrameLayout with Recyclerview

I want to put the bottom navigation menu with my recyclerview at the bottom of the view. It is currently at the top and I need help sending it to the bottom.
This is how it look now:
This is my xml code:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="#+id/titleTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="20dp"
android:layout_marginTop="20dp"
android:text="Oficinas Credenciadas"
android:textColor="#android:color/black"
android:textSize="30sp"
android:textStyle="bold"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/listRecyclerView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="1dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="1dp"
android:layout_marginBottom="1dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/titleTextView" />
<FrameLayout
android:id="#+id/frame"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
app:layout_constraintTop_toBottomOf="#+id/titleTextView"
/>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:menu="#menu/botton_nav_menu"
tools:ignore="MissingConstraints" />
</androidx.constraintlayout.widget.ConstraintLayout>

Add
app:layout_constraintBottom_toBottomOf="parent"
To bottom navigation item so code will be like that
<com.google.android.material.bottomnavigation.BottomNavigationView
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:menu="#menu/botton_nav_menu"
tools:ignore="MissingConstraints" />

I have made some changes and this is how it the items are positioned now.
This is how the code looks now. If this helps you, an upvote would be appreciated. Thanks
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/titleTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:text="Oficinas Credenciadas"
android:textColor="#android:color/black"
android:textSize="30sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/listRecyclerView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="1dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="1dp"
android:layout_marginBottom="1dp"
app:layout_constraintBottom_toTopOf="#+id/bottom_menu"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/titleTextView" />
<!-- NOT SURE WHY YOU HAVE THE FRAMELAYOUT AND RECYCLERVIEW OCCUPYING THE SAME SPACE BUT IF YOU INTEND TO HIDE AND SHOW THEM AT DIFFERENT TIMES, I HAVE IMPROVED THEIR CONSTRAINTS -->
<FrameLayout
android:id="#+id/frame"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
app:layout_constraintBottom_toTopOf="#+id/bottom_menu"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/titleTextView"
/>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/bottom_menu"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:menu="#menu/sample_menu"
tools:ignore="MissingConstraints" />
</androidx.constraintlayout.widget.ConstraintLayout>

Android Textview not aligning to top of page

I am having trouble aligning my UI components to top of the constraint layout even though I have constraint them to the start of the page. There is a tiny gap between the ToolBar and where the UI components start. app:layout_constraintTop_toTopOf="parent" -> this line of code always works but I believe the problem could be that I am using a tabbed activity that it might not be compatible.Problem in UI
Any help or guidance would be greatly appreciated.
This is my XML class ->
<ScrollView android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_height="wrap_content"
android:layout_width="match_parent">
<TextView
android:id="#+id/breakfastTV"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="9dp"
android:layout_weight="10"
android:text="Breakfast"
android:textAppearance="#style/TextAppearance.AppCompat.Body2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/breakfastRecyclerView"
android:layout_width="match_parent"
android:layout_height="200dp"
android:layout_weight="1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/breakfastTV" />
<TextView
android:id="#+id/lunchTV"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="9dp"
android:layout_weight="10"
android:text="Lunch"
android:textAppearance="#style/TextAppearance.AppCompat.Body2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/breakfastRecyclerView" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/lunchRecyclerView"
android:layout_width="match_parent"
android:layout_height="200dp"
android:layout_weight="1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/lunchTV" />
<TextView
android:id="#+id/dinnerTV"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="9dp"
android:layout_weight="10"
android:text="Dinner"
android:textAppearance="#style/TextAppearance.AppCompat.Body2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/lunchRecyclerView" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/dinnerRecyclerView"
android:layout_width="match_parent"
android:layout_height="200dp"
android:layout_weight="1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/dinnerTV" />
<TextView
android:id="#+id/otherTV"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="9dp"
android:layout_weight="10"
android:text="Other"
android:textAppearance="#style/TextAppearance.AppCompat.Body2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/dinnerRecyclerView" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/otherRecyclerView"
android:layout_width="match_parent"
android:layout_height="200dp"
android:layout_weight="1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/otherTV" />
</androidx.constraintlayout.widget.ConstraintLayout>
CLASS WITH Toolbar ->
<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/a"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context=".Management"
tools:openDrawer="start">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:elevation="4dp"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light">
</androidx.appcompat.widget.Toolbar>
</LinearLayout>
<FrameLayout
android:id="#+id/fragLayout"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/topNavigation"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/topNavigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:menu="#menu/mgmt_bottom_nav_bar" />
</androidx.constraintlayout.widget.ConstraintLayout>
<com.google.android.material.navigation.NavigationView
android:id="#+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
app:headerLayout="#layout/nav_header"
app:menu="#menu/drawer_menu" />
</androidx.drawerlayout.widget.DrawerLayout>

Recyclerview very slow to load

I have a recycler view in an Activity where sometimes I show a lot of elements. The problem is that when the number of elements is very high the recycler view needs some seconds to render the elements and it's frustrating. I wonder why.
My code:
<android.support.v4.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="cct.appload.fragments.FileManagerFragment">
<LinearLayout
android:id="#+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:focusableInTouchMode="true">
<Spinner
android:id="#+id/_order_spinner"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginTop="8dp"
android:contentDescription="#string/back"
android:src="#drawable/ic_arrow_back_black_24dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
<android.support.v7.widget.CardView xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="#+id/card_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginTop="8dp"
android:elevation="1dp"
card_view:cardCornerRadius="0dp"
card_view:cardElevation="2dp">
<TextView
android:id="#+id/_msg"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="16dp"
android:gravity="center"
android:visibility="invisible" />
<ProgressBar
android:id="#+id/manager_progress_bar"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_gravity="center"
android:progressTint="#color/colorAccent"
android:visibility="invisible" />
<android.support.v7.widget.RecyclerView
android:id="#+id/_recycler_view"
android:layout_width="match_parent"
android:nestedScrollingEnabled="false"
android:layout_height="wrap_content"
android:paddingStart="8dp"
android:paddingEnd="8dp"
android:scrollbars="vertical" />
</android.support.v7.widget.CardView>
</LinearLayout>
My single item:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/_container"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="#+id/_icon"
android:layout_width="44dp"
android:layout_height="44dp"
android:layout_marginBottom="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:background="#drawable/circle_background"
android:padding="10dp"
android:tint="#color/white"
app:layout_constraintBottom_toTopOf="#+id/_separator"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/ic_folder_black_24dp" />
<TextView
android:id="#+id/_titolo"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:ellipsize="end"
android:lines="1"
android:maxLines="1"
android:text="Titolo"
android:textAppearance="#android:style/TextAppearance.Material.Body2"
app:layout_constraintEnd_toStartOf="#+id/_menu"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toEndOf="#+id/_icon"
app:layout_constraintTop_toTopOf="#+id/_icon" />
<TextView
android:id="#+id/_dimensione"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:padding="0dp"
android:text="dimensione"
android:ellipsize="end"
android:lines="1"
app:layout_constraintBottom_toBottomOf="#+id/_icon"
app:layout_constraintEnd_toStartOf="#+id/_menu"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toEndOf="#+id/_icon"
app:layout_constraintTop_toBottomOf="#+id/_titolo" />
<ImageButton
android:id="#+id/_menu"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:background="#android:color/transparent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/ic_more_vert_black_24dp" />
<View
android:id="#+id/_separator"
android:layout_width="match_parent"
android:layout_height="1dp"
android:layout_marginBottom="0dp"
android:background="#color/lightGrey"
app:layout_constraintBottom_toBottomOf="parent" />
</android.support.constraint.ConstraintLayout>
In order to update the elements I simply change the list of them and then I notify that to the recycler view.

I think the best solution is not loading all data, just using lazy-loading
Refer here

I had a problem with a very small amount of items. I'm using Room Dao.
The reason why RecycleView ran so slow was the fact that photos that l used were large in size. So be careful about that.

TabLayout load Fragments but its BottomNavigationView not showing on bottom

TabLayout call and load Fragments. Fragments preview no problem, everythink ok. Problem start after load fragments. BottomNavigationView
android:layout_alignParentBottom="true"
not show in bottom. But change position to top there is no problem, it is show.
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/message"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="#dimen/activity_horizontal_margin"
android:layout_marginStart="#dimen/activity_horizontal_margin"
android:layout_marginTop="#dimen/activity_vertical_margin"
android:text="#string/yazarlar"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigation"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:menu="#menu/navigation" />
</android.support.constraint.ConstraintLayout>

Actually, I don't see in your code anything like
android:layout_alignParentBottom="true"
So that means, that in your previous code, you used RelativeLayout as parent, so please post your original code. I would recommend you using something like this:
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigation"
android:layout_width="0dp"
android:layout_height="0dp"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:menu="#menu/navigation" />

Insert this code android:layout_alignParentBottom="true" not shown in fragment. I try some layout. Orginal layout
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/message"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="#dimen/activity_horizontal_margin"
android:layout_marginStart="#dimen/activity_horizontal_margin"
android:layout_marginTop="#dimen/activity_vertical_margin"
android:text="#string/yazarlar"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigation"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
android:layout_alignParentBottom="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:menu="#menu/navigation" />
</RelativeLayout>

Constraint Layout textview width set to 0dp is not showing

I'm using an android intro book to set up a Constraint Layout which i think I've done correctly. The preview looks perfect, but when I run it the textviews don't show up, only the image view.
If I change the textviews' widths to "wrap_content" they show up but the format is wrong. This leads me to believe the problem is that the width is to "0dp". I don't understand why this is happening, my xml is identical to the books'. Any feedback for a beginner would be appreciated.
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="81dp">
<TextView
android:id="#+id/crime_title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginLeft="16dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:text="Crime Title"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="#+id/imageView"
app:layout_constraintTop_toTopOf="parent"/>
<TextView
android:id="#+id/crime_date"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginLeft="16dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:text="Crime Date"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="#+id/imageView"
app:layout_constraintTop_toBottomOf="#+id/crime_title"/>
<ImageView
android:id="#+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="#drawable/ic_solved"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="16dp"
android:layout_marginRight="16dp"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginBottom="16dp"/>
</android.support.constraint.ConstraintLayout>