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DialogFragment custom view no background

I'm trying to inflate a custom view in a DialogFragment but the container view's are not showing up. Note I haven't found any post that matches this exactly, so if there is, please share, TIA.
here is my XML (very simple)
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:background="#drawable/billnotifselectiondialog"
android:layout_marginHorizontal="45dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent">
<Button
android:id="#+id/btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
android:background="#color/secondary_200"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
My Class:
class BillNotifSelectionDialog: DialogFragment() {
private lateinit var binding: TestDialogLayoutBinding
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View = TestDialogLayoutBinding.inflate(LayoutInflater.from(context),container, false).apply {
binding = this
}.root
}
I'm invoking the class in my fragment with
BillNotifSelectionDialog().show(parentFragmentManager, "tag")
Here is the result, I can only see the button, not the ConstraintLayout:

This is a common issue of using ConstraintLayout as the root layout of DialogFragments.
One fix is to Replace it with RelativeLayout; but it's not recommended as per documentation quote:
For better performance and tooling support, you should instead build your layout with ConstraintLayout.
Instead of that you'd fix it programmatically by designating the dialog layout to match the parent with dialog.window.setLayout:
class BillNotifSelectionDialog : DialogFragment() {
//..... rest of code omitted
override fun onStart() {
super.onStart()
dialog!!.window!!.setLayout(MATCH_PARENT, MATCH_PARENT)
}
}

you need to override onCreateDialog instead of onCreateView in DialogFragment.
class BillNotifSelectionDialog : DialogFragment() {
private lateinit var binding: TestDialogLayoutBinding
override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
binding = TestDialogLayoutBinding.inflate(layoutInflater)
return AlertDialog.Builder(requireContext())
.setView(binding.root)
.create()
}
to test the result, I changed your xml code that the background color is teal_200 and button color is purple_700
the code result

Why does BottomSheetDialog draw under the navigation bar in landscape?

I am showing a simple Android modal bottom sheet menu. In portrait mode, it works fine, but when the device is rotated to landscape the bottom of the sheet draws under the navigation bar and is hidden. This is using a tablet emulator (Pixel C, API 32).
Portrait mode: correct
Landscape mode: bottom of sheet is hidden
Sample code, using the Android Studio "Empty Activity" template project and code from the Material docs.
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
binding.showDialog.setOnClickListener { showBottomSheetDialog() }
}
private fun showBottomSheetDialog() {
val modalBottomSheet = ModalBottomSheet()
modalBottomSheet.show(supportFragmentManager, ModalBottomSheet.TAG)
}
}
class ModalBottomSheet : BottomSheetDialogFragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? = inflater.inflate(R.layout.bottom_sheet_dialog, container, false)
companion object {
const val TAG = "ModalBottomSheet"
}
}
bottom_sheet_dialog.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="#+id/text_view_1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="30dp"
android:paddingVertical="12dp"
android:text="First Row"
android:textSize="16sp" />
<TextView
android:id="#+id/text_view_2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="30dp"
android:paddingVertical="12dp"
android:text="Second Row"
android:textSize="16sp" />
<TextView
android:id="#+id/text_view_3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="30dp"
android:paddingVertical="12dp"
android:text="Third Row"
android:textSize="16sp" />
</LinearLayout>

This appears to be intentional Android tablet UI behaviour. (It's a mystery why it is desirable to start a bottom sheet off in a state where the user can't see its content, but anyway...)
Fixed by adding this into the ModalBottomSheet class:
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
dialog?.setOnShowListener {
(it as? BottomSheetDialog)?.apply {
behavior.state = BottomSheetBehavior.STATE_EXPANDED
}
}
}
With thanks to the answers posted in Why does BottomSheetDialog draw under the navigation bar in landscape?

I feel the screen can render only 2 times space in Landscape mode as per your design.
Try to provide scrolling feature so that it will support in both Portrait and Landscape mode even in future if you add more items to BottomSheet.

Jumping scrolling when switching fragments

Inside a ScrollView I am dynamically switching between two fragments with different heights.
Unfortunately that leads to jumping. One can see it in the following animation:
I am scrolling down until I reach the button "show yellow".
Pressing "show yellow" replaces a huge blue fragment with a tiny yellow fragment. When this happens, both buttons jump down to the end of the screen.
I want both buttons to stay at the same position when switching to the yellow fragment. How can that be done?
Source code available at https://github.com/wondering639/stack-dynamiccontent respectively https://github.com/wondering639/stack-dynamiccontent.git
Relevant code snippets:
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.core.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/myScrollView"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="#+id/textView"
android:layout_width="0dp"
android:layout_height="800dp"
android:background="#color/colorAccent"
android:text="#string/long_text"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/button_fragment1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:text="show blue"
app:layout_constraintEnd_toStartOf="#+id/button_fragment2"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView" />
<Button
android:id="#+id/button_fragment2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:text="show yellow"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toEndOf="#+id/button_fragment1"
app:layout_constraintTop_toBottomOf="#+id/textView" />
<FrameLayout
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="#+id/button_fragment2">
</FrameLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
MainActivity.kt
package com.example.dynamiccontent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// onClick handlers
findViewById<Button>(R.id.button_fragment1).setOnClickListener {
insertBlueFragment()
}
findViewById<Button>(R.id.button_fragment2).setOnClickListener {
insertYellowFragment()
}
// by default show the blue fragment
insertBlueFragment()
}
private fun insertYellowFragment() {
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.fragment_container, YellowFragment())
transaction.commit()
}
private fun insertBlueFragment() {
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.fragment_container, BlueFragment())
transaction.commit()
}
}
fragment_blue.xml:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="400dp"
android:background="#0000ff"
tools:context=".BlueFragment" />
fragment_yellow.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="20dp"
android:background="#ffff00"
tools:context=".YellowFragment" />
HINT
Please note that this is of course a minimum working example to show off my issue. In my real project, I also have views below the #+id/fragment_container. So giving a fixed size to #+id/fragment_container is not an option for me - it would cause a large blank area when switching to the low, yellow fragment.
UPDATE: Overview of proposed solutions
I implemented the proposed solutions for testing purposes and added my personal experiences with them.
answer by Cheticamp, https://stackoverflow.com/a/60323255
-> available in https://github.com/wondering639/stack-dynamiccontent/tree/60323255
-> FrameLayout wraps content, short code
answer by Pavneet_Singh, https://stackoverflow.com/a/60310807
-> available in https://github.com/wondering639/stack-dynamiccontent/tree/60310807
-> FrameLayout gets the size of the blue fragment. So no content wrapping. When switching to the yellow fragment, there's a gap between it and the content following it (if any content follows it). No additional rendering though!
** update ** a second version was provided showing how to do it without gaps. Check the comments to the answer.
answer by Ben P., https://stackoverflow.com/a/60251036
-> available in https://github.com/wondering639/stack-dynamiccontent/tree/60251036
-> FrameLayout wraps content. More code than the solution by Cheticamp. Touching the "show yellow" button twice leads to a "bug" (buttons jump down to the bottom, actually my original issue). One could argue about just disabling the "show yellow" button after switching to it, so I wouldn't consider this a real issue.

Update: To keep the other views right below the framelayout and to handle the scenario automatically, we need to use onMeasure to implement the auto-handling so do the following steps
• Create a custom ConstraintLayout as (or can use MaxHeightFrameConstraintLayout lib):
import android.content.Context
import android.os.Build
import android.util.AttributeSet
import androidx.constraintlayout.widget.ConstraintLayout
import kotlin.math.max
/**
* Created by Pavneet_Singh on 2020-02-23.
*/
class MaxHeightConstraintLayout #kotlin.jvm.JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : ConstraintLayout(context, attrs, defStyleAttr){
private var _maxHeight: Int = 0
// required to support the minHeight attribute
private var _minHeight = attrs?.getAttributeValue(
"http://schemas.android.com/apk/res/android",
"minHeight"
)?.substringBefore(".")?.toInt() ?: 0
override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
_minHeight = minHeight
}
var maxValue = max(_maxHeight, max(height, _minHeight))
if (maxValue != 0 && && maxValue > minHeight) {
minHeight = maxValue
}
_maxHeight = maxValue
super.onMeasure(widthMeasureSpec, heightMeasureSpec)
}
}
and use it in your layout in place of ConstraintLayout
<?xml version="1.0" encoding="utf-8"?>
<androidx.core.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/myScrollView"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.example.pavneet_singh.temp.MaxHeightConstraintLayout
android:id="#+id/constraint"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="#+id/textView"
android:layout_width="0dp"
android:layout_height="800dp"
android:background="#color/colorAccent"
android:text="Some long text"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/button_fragment1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:text="show blue"
app:layout_constraintEnd_toStartOf="#+id/button_fragment2"
app:layout_constraintHorizontal_bias="0.3"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView" />
<Button
android:id="#+id/button_fragment2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:text="show yellow"
app:layout_constraintHorizontal_bias="0.3"
app:layout_constraintStart_toEndOf="#+id/button_fragment1"
app:layout_constraintTop_toBottomOf="#+id/textView" />
<Button
android:id="#+id/button_fragment3"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:text="show green"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.3"
app:layout_constraintStart_toEndOf="#+id/button_fragment2"
app:layout_constraintTop_toBottomOf="#+id/textView" />
<FrameLayout
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="#id/button_fragment3" />
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="additional text\nMore data"
android:textSize="24dp"
app:layout_constraintTop_toBottomOf="#+id/fragment_container" />
</com.example.pavneet_singh.temp.MaxHeightConstraintLayout>
</androidx.core.widget.NestedScrollView>
This will keep track of height and apply it during every fragment change.
Output:
Note: As mentioned in comments before, setting minHeight will result in additional rendering pass and it cannot be avoided in the current version of ConstraintLayout.
Old approach with custom FrameLayout
This is an interesting requirement and my approach is to solve it by creating a custom view.
Idea:
My idea for the solution is to adjust the height of the container by keeping the track of the largest child or total height of children in the container.
Attempts:
My first few attempts were based on modifying the existing behaviour of NestedScrollView by extending it but it doesn't provide access to all the necessary data or methods. Customisation resulted in poor support for all scenarios and edge cases.
Later, I achieved the solution by creating a custom Framelayout with different approach.
Solution Implementation
While implementing the custom behaviour of height measurement phases, I dug deeper and manipulated the height with getSuggestedMinimumHeight while tracking the height of children to implement the most optimised solution as it will not cause any additional or explicit rendering because it will manage the height during the internal rendering cycle so create a custom FrameLayout class to implement the solution and override the getSuggestedMinimumHeight as:
class MaxChildHeightFrameLayout #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : FrameLayout(context, attrs, defStyleAttr) {
// to keep track of max height
private var maxHeight: Int = 0
// required to get support the minHeight attribute
private val minHeight = attrs?.getAttributeValue(
"http://schemas.android.com/apk/res/android",
"minHeight"
)?.substringBefore(".")?.toInt() ?: 0
override fun getSuggestedMinimumHeight(): Int {
var maxChildHeight = 0
for (i in 0 until childCount) {
maxChildHeight = max(maxChildHeight, getChildAt(i).measuredHeight)
}
if (maxHeight != 0 && layoutParams.height < (maxHeight - maxChildHeight) && maxHeight > maxChildHeight) {
return maxHeight
} else if (maxHeight == 0 || maxHeight < maxChildHeight) {
maxHeight = maxChildHeight
}
return if (background == null) minHeight else max(
minHeight,
background.minimumHeight
)
}
}
Now replace the FrameLayout with MaxChildHeightFrameLayout in activity_main.xml as:
<?xml version="1.0" encoding="utf-8"?>
<androidx.core.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/myScrollView"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="#+id/textView"
android:layout_width="0dp"
android:layout_height="800dp"
android:background="#color/colorAccent"
android:text="Some long text"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/button_fragment1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:text="show blue"
app:layout_constraintEnd_toStartOf="#+id/button_fragment2"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView" />
<Button
android:id="#+id/button_fragment2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:text="show yellow"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toEndOf="#+id/button_fragment1"
app:layout_constraintTop_toBottomOf="#+id/textView" />
<com.example.pavneet_singh.temp.MaxChildHeightFrameLayout
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:minHeight="2dp"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="#+id/button_fragment2"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.core.widget.NestedScrollView>
getSuggestedMinimumHeight() will be used to calculate the height of the view during the view rendering lifecycle.
Output:
With more views, fragment and different height. (400dp, 20dp, 500dp respectively)

A straightforward solution is to adjust the minimum height of the ConstraintLayout within the NestedScrollView before switching fragments. To prevent jumping, the height of the ConstraintLayout must be greater than or equal to
the amount by which the NestedScrollView has scrolled in the "y" direction
plus
the height of the NestedScrollView.
The following code encapsulates this concept:
private fun adjustMinHeight(nsv: NestedScrollView, layout: ConstraintLayout) {
layout.minHeight = nsv.scrollY + nsv.height
}
Please note that layout.minimumHeight will not work for ConstraintLayout. You must use layout.minHeight.
To invoke this function, do the following:
private fun insertYellowFragment() {
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.fragment_container, YellowFragment())
transaction.commit()
val nsv = findViewById<NestedScrollView>(R.id.myScrollView)
val layout = findViewById<ConstraintLayout>(R.id.constraintLayout)
adjustMinHeight(nsv, layout)
}
It is similar for insertBlueFragment(). You can, of course, simplify this by doing findViewById() once.
Here is a quick video of the results.
In the video, I have added a text view at the bottom to represent additional items that may exist in your layout below the fragment. If you delete that text view, the code will still work, but your will see blank space at the bottom. Here is what that looks like:
And if the views below the fragment don't fill the scroll view, you will see the additional views plus white space at the bottom.

Your FrameLayout inside activity_main.xml has a height attribute of wrap_content.
Your child fragment layouts are determining the height differences you're seeing.
Should post up your xml for the child fragments
Try setting a specific height to the FrameLayout in your activity_main.xml

I solved this by creating a layout listener that keeps track of the "previous" height and adds padding to the ScrollView if the new height is less than before.
HeightLayoutListener.kt
class HeightLayoutListener(
private val activity: MainActivity,
private val root: View,
private val previousHeight: Int,
private val targetScroll: Int
) : ViewTreeObserver.OnGlobalLayoutListener {
override fun onGlobalLayout() {
root.viewTreeObserver.removeOnGlobalLayoutListener(this)
val padding = max((previousHeight - root.height), 0)
activity.setPaddingBottom(padding)
activity.setScrollPosition(targetScroll)
}
companion object {
fun create(fragment: Fragment): HeightLayoutListener {
val activity = fragment.activity as MainActivity
val root = fragment.view!!
val previousHeight = fragment.requireArguments().getInt("height")
val targetScroll = fragment.requireArguments().getInt("scroll")
return HeightLayoutListener(activity, root, previousHeight, targetScroll)
}
}
}
To enable this listener, add this method to both of your fragments:
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val listener = HeightLayoutListener.create(this)
view.viewTreeObserver.addOnGlobalLayoutListener(listener)
}
These are the methods that the listener calls in order to actually update the ScrollView. Add them to your activity:
fun setPaddingBottom(padding: Int) {
val wrapper = findViewById<View>(R.id.wrapper) // add this ID to your ConstraintLayout
wrapper.setPadding(0, 0, 0, padding)
val widthMeasureSpec = View.MeasureSpec.makeMeasureSpec(wrapper.width, View.MeasureSpec.EXACTLY)
val heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED)
wrapper.measure(widthMeasureSpec, heightMeasureSpec)
wrapper.layout(0, 0, wrapper.measuredWidth, wrapper.measuredHeight)
}
fun setScrollPosition(scrollY: Int) {
val scroll = findViewById<NestedScrollView>(R.id.myScrollView)
scroll.scrollY = scrollY
}
And you need to set arguments to your fragments in order for the listener to know what the previous height and the previous scroll position were. So make sure to add them to your fragment transactions:
private fun insertYellowFragment() {
val fragment = YellowFragment().apply {
this.arguments = createArgs()
}
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.fragment_container, fragment)
transaction.commit()
}
private fun insertBlueFragment() {
val fragment = BlueFragment().apply {
this.arguments = createArgs()
}
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.fragment_container, fragment)
transaction.commit()
}
private fun createArgs(): Bundle {
val scroll = findViewById<NestedScrollView>(R.id.myScrollView)
val container = findViewById<View>(R.id.fragment_container)
return Bundle().apply {
putInt("scroll", scroll.scrollY)
putInt("height", container.height)
}
}
And that should do it!

How to hide bottom app bar on scroll in android

I am making an android application which has an activity and other activity implements the main activity.Now i am also implementing one activity many fragment pattern.So each activity has at least 7-8 fragment inside that.
Here is layout for my main activity.
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="60dp"
android:id="#+id/frame_lay">
</FrameLayout>
<View
android:layout_width="match_parent"
android:layout_height="4dp"
android:layout_above="#id/bottom_appbar"
app:layout_anchor="#+id/bottom_appbar"
android:background="#android:color/darker_gray"/>
<com.google.android.material.bottomappbar.BottomAppBar
android:id="#+id/bottom_appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
app:backgroundTint="#color/colorbottomappbar"
app:fabAlignmentMode="center"
app:navigationIcon="#drawable/ic_menu_green_24dp">
</com.google.android.material.bottomappbar.BottomAppBar>
<ImageButton
android:id="#+id/fab"
android:layout_width="190dp"
android:layout_height="80dp"
android:visibility="visible"
app:layout_anchorGravity="center_horizontal|bottom"
android:background="#drawable/logo"
app:layout_anchor="#+id/bottom_appbar"
android:layout_marginBottom="17dp"/>
<ImageButton
android:id="#+id/fab_two"
android:layout_width="190dp"
android:layout_height="80dp"
android:visibility="gone"
app:layout_anchorGravity="center_horizontal|bottom"
android:background="#drawable/logotwo"
android:elevation="5dp"
app:layout_anchor="#+id/bottom_appbar"
android:layout_marginBottom="13dp">
</ImageButton>
You can see that my main activity has frame layout in it in which i transact all the fragments.I used image button in place of floating action button as i want floating action button of oval shape.Now what i want that inside fragment when user scrolls then the image button , bottomappbar and the view which is horizontal line hides? The bottom app bar is being used in many fragments so i need a code which i can write in a activity which hides the bottomapp bar and the image button on while users scroll inside fragment.How can i achieve this? I am sorry for my silly question as i am new to android development .Thanks in advance.

You can achieve this by putting the below two lines in xml
app:hideOnScroll="true"
app:layout_scrollFlags="scroll|enterAlways"
So the full xml tag will be
<com.google.android.material.bottomappbar.BottomAppBar
android:id="#+id/bottom_app_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
app:fabAlignmentMode="center"
app:hideOnScroll="true"
app:layout_scrollFlags="scroll|enterAlways"/>

Because you are scrolling inside a Fragment, you need to pass the scrolling values to your activity.
I suggest you use the default InteractionInterface that Android Studio generated in Fragment's template:
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val root = inflater.inflate(R.layout.fragment_blank, container, false)
root.scrollView2.setOnScrollChangeListener { v, scrollX, scrollY, oldScrollX, oldScrollY ->
// the key is here.
var delta = scrollY - oldScrollY
listener?.onFragmentScrolled(delta)
}
return inflater.inflate(R.layout.fragment_blank, container, false)
}
interface OnFragmentInteractionListener {
// Name your function here
fun onFragmentScrolled(delta: Float)
}
// the lines below are generated,
// not the key point here but important to binding listener
override fun onAttach(context: Context) {
super.onAttach(context)
if (context is OnFragmentInteractionListener) {
listener = context
} else {
throw RuntimeException(context.toString() + " must implement OnFragmentInteractionListener")
}
}
override fun onDetach() {
super.onDetach()
listener = null
}
And then, in YourActivity, implement YourFragment.OnFragmentInteractionListener
Override the function
override fun onFragmentScrolled(delta: Float) {
anotherView.translationY = anotherView.translationY + delta
if (anotherView.translationY > anotherView.height)
anotherView.translationY = anotherView.height.toFloat()
if (anotherView.translationY < 0)
anotherView.translationY = 0f
}
the result will be like this mp4 link
The main point is : Pass your scrolling action from Fragment to Activity,
You can achieve this in many ways, this is just the basic one;

A similar approach to Wesely's is the following.
Let assume we have something like this:
A custom bottom appbar and we have at least one fragment per action.
What I mean is that activity main is the parent where all the fragments are going to place in.
You can declare an interface in main activity (in this example I want to hide/show a custom bottom appbar and FAB) to perform show/hide of the bottom appbar and fab (both of them in activity_main.xml), so the interface would look something like this:
class MainActivity : AppCompatActivity(), OnScrollListenerMain {
...
override fun fabAndBottomAppBarHide() {
if (fab_main.isVisible) {
fab_main.hide()
bottom_app_bar.performHide()
}
}
override fun fabAndBottomAppBarShow() {
if (!fab_main.isVisible) {
fab_main.show()
bottom_app_bar.performShow()
}
}
...
} // end Main
interface OnScrollListenerMain {
fun fabAndBottomAppBarHide()
fun fabAndBottomAppBarShow()
}
Once the interface is defined in main activity, every fragment with a Nested scroll view can implement it.
<androidx.core.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/nsv_fragment_with_scroll"
... >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
...
</LinearLayout>
</androidx.core.widget.NestedScrollView>
Creating a reference to the NestedScrollView and attaching the onScrollChangeListener will help us to check when there is a change in the scroll over the y axis
class FragmentWithScroll : Fragment() {
lateinit var mScroll:NestedScrollView
...
override fun onCreateView( inflater: LayoutInflater, container: ViewGroup?,savedInstanceState: Bundle?): View? {
// Inflate the layout for this fragment
val view = inflater.inflate(R.layout.fragment_with_scroll,container,false)
mScroll = view.findViewById(R.id.nsv_fragment_with_scroll)
mScroll.setOnScrollChangeListener { v: NestedScrollView?, _: Int, scrollY: Int, _: Int, oldScrollY: Int ->
val dy = oldScrollY - scrollY
if (dy < 0) {
(v!!.context as OnScrollListenerMain).fabAndBottomAppBarHide()
} else if (dy > 0) {
(v!!.context as OnScrollListenerMain).fabAndBottomAppBarShow()
}
}
...
return view
}
}
Remember in Kotlin we can use _ when the parameter in the lambda is never used.
So basically the change in y is val dy = oldScrollY - scrollY and dy is negative when the scroll is from bottom to top and this condition dy < 0 is true, so we use the context of the view to invoke OnScrollListenerMain.fabAndBottomAppBarHide()
and again dy is positive when the scroll is from top to bottom and this condition dy > 0 is true, so we use the context of the view to invoke OnScrollListenerMain.fabAndBottomAppBarShow()
But, what if we just want to hide a BottomAppbar (without hiding FAB)?
The BottomAppbar might be child of Coordinator layout and the fragments need to have a NestedScrollView, RecyclerView or ScrollView as parent in their XML, so the main activity XML should look something like:
<androidx.coordinatorlayout.widget.CoordinatorLayout
android:id="#+id/coordinator_main"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:id="#+id/lly_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" />
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="#+id/fab_main"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:adjustViewBounds="true"
android:src="#drawable/ic_add"
app:borderWidth="0dp"
app:layout_anchor="#+id/bottom_app_bar" />
<com.google.android.material.bottomappbar.BottomAppBar
android:id="#+id/bottom_app_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
app:fabAlignmentMode="center"
app:hideOnScroll="true">
</com.google.android.material.bottomappbar.BottomAppBar>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
The fragments should be placed into lly_main and this line makes the trick: app:hideOnScroll="true"

You can achieve this by adding the following attribute to your BottomAppBar:
app:layout_behavior="#string/hide_bottom_view_on_scroll_behavior"

Why my foreach breaks when I try to draw dynamic buttons in Kotlin?

I need to draw dynamic buttons inside a foreach loop that retrieve data from my anko sqlite, the foreach only enter once and breaks and only draw one button in my layout, what I doing wrong? my code is this:
fun loadZones (ctx: Context, update: String, view: View, layout: LinearLayout) {
val zonesParser = rowParser{idzone: Int, zone: String -> Pair(idzone, zone)}
for (it in ctx.database.use {
select("tableplan")
.distinct()
.column("idzone")
.column("zone")
.orderBy("zone")
.parseList(zonesParser)
}) {
val layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT)
val btnZone = layoutInflater.inflate(R.layout.zones_item, null) as MaterialButton
btnZone.text = it.second
btnZone.id = it.first
layout.addView(btnZone, layoutParams)
Log.e("PAIR", "FIN DEL CICLO")
continue
}
}
The data that retrieves from my query is this:
(2, LARRY)
(1, MADISON)
That's my activity, I need to draw the buttons in "lytZonesButtons" id
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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=".TablePlanFragment">
<com.google.android.material.appbar.AppBarLayout android:layout_width="match_parent"
android:layout_height="wrap_content" android:elevation="2dp"
tools:targetApi="lollipop" app:liftOnScroll="true">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbarTablePlan"
style="#style/com.madison.Toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:title="#string/table_title_module">
</androidx.appcompat.widget.Toolbar>
</com.google.android.material.appbar.AppBarLayout>
<LinearLayout
android:layout_marginTop="56dp"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:orientation="horizontal"
android:background="#color/orangeLighter"
android:gravity="center_vertical"
android:padding="5dp" android:id="#+id/lytZonesButtons" />
<androidx.core.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="112dp"
android:padding="5dp">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rc_tableplan"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</androidx.core.widget.NestedScrollView>
</FrameLayout>
and that's my button template that I called "zones_item":
<?xml version="1.0" encoding="utf-8"?>
<com.google.android.material.button.MaterialButton
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" style="#style/com.madison.AppButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="#style/TextAppearance.MaterialComponents.Subtitle2"
tools:text="MADISON"
tools:targetApi="lollipop"
android:layout_margin="5dp"
/>
EDIT: I found the solution!
I don't now why my layout instance in the twice iteration of my loop throws NullPointerException but not shows in the log cat, my solution was put the loop code in onCreateView function, this is the code:
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
val view = inflater.inflate(R.layout.activity_tableplan, container, false)
val iActivity = (activity as AppCompatActivity)
iActivity.setSupportActionBar(view.toolbarTablePlan)
iActivity.supportActionBar?.setDisplayShowTitleEnabled(true)
// view.rc_tableplan.setHasFixedSize(true)
// val gridLayoutManager = GridLayoutManager(context, 2, GridLayoutManager.HORIZONTAL, false)
// view.rc_tableplan.layoutManager = gridLayoutManager
val response = loadTablePlan(this.context!!, "no")
if (response.trim().toUpperCase() == "SUCCESS") {
val zonesParser = rowParser{idzone: Int, zone: String -> Pair(idzone, zone)}
for (zone in this.context!!.database.use {
select("tableplan")
.distinct()
.column("idzone")
.column("zone")
.orderBy("zone")
.parseList(zonesParser)
}) {
val layout:LinearLayout = view.lytZonesButtons
layout.let {
val btnZone = layoutInflater.inflate(R.layout.zones_item, layout, false) as MaterialButton
btnZone.text = zone.second
btnZone.id = zone.first
btnZone.requestLayout()
layout.addView(btnZone)
Log.e("PAIR", "FIN DEL CICLO")
}
}
}
return view
}
Thanks a lot for all people that tried help me, some admin can close my question please.

The hint is only one button is showing. Your trying to inflate the same view twice in the same spot.
You need to add an empty linearlayout in your xml. And in your loop change the buttonz..
var btnZone = findViewById(R.layout.btnZone)
button.text = "Pair"
btnZone.addView(button, layoutParams)
That's not the exact code (and probably not even the right syntax) but it shows you how you need to modify your loop.
Basicly you were attempting to inflate the same instance of the same view. When really your not inflating any views this way your just adding views.
Note
If you have a linearlayout in your xml when you add another button view to it it will add it below it. If you set the layout orientation to horizontal the button view then gets added beside the other one.
here's a link to an example.
Sorry I would make sure my code matched your code and variables with proper syntax but I am at work.