Develop Reference

Inexplicable white/blank space in Android app, not showing in layout preview

The preview looks fine, but the app runs differently. In the layout inspector, there is simply nothing where this weird white space is. It seems to be a problem with ConstraintLayout + ViewPager. I had the same issue in three places, all with same ViewPager, 0dp vertical size setup. I have solved by converting ConstraintLayouts into LinearLayouts. But the question is why do I need to regress to a LinearLayout? I originally wrote the UI with ConstraintLayout, and ViewPager, it was fine. Somewhere along the way, without touching the code, things turned weird and this blank space showed up. As if something in Android UI rendering changed under the hood. Anyone have any idea what it is, or how to solve while keeping a ConstraintLayout?
Here is the layout inspector image of the app running on a device. I have clearly marked the problematic white space with my mouse calligraphy skills.
Here is the layout preview for the following xml code, note UI elements fill the screen, no white space after the bottom toolbar in this view, unlike live app. Don't mind the colour difference, the app changes colours at run time.
fragment_layout.xml (Between green and marked blank space in live app image, the rest of UI is from activity, but I know that's not the problem, so won't add the xml for that)
<?xml version="1.0" encoding="utf-8"?>
<layout
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">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.order.OrderBuildFragment"
>
<com.google.android.material.tabs.TabLayout
android:id="#+id/order_tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabMode="fixed"
app:layout_constraintBottom_toTopOf="#+id/order_viewpager"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"/>
<androidx.viewpager.widget.ViewPager
android:id="#+id/order_viewpager"
android:layout_width="match_parent"
android:layout_height="0dp"
android:background="#android:color/white"
app:layout_constraintTop_toBottomOf="#id/order_tabs"
app:layout_constraintBottom_toTopOf="#id/build_order_bottom_toolbar"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent">
</androidx.viewpager.widget.ViewPager>
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/build_order_bottom_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="#id/order_viewpager"
app:layout_constraintBottom_toBottomOf="parent"
android:background="?attr/colorPrimary"
>
<TextView
android:id="#+id/order_service_point_spinner_label"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="#string/service_point"
android:textColor="#color/white"
app:layout_constraintEnd_toStartOf="#id/order_toolbar_service_point_spinner"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="#id/build_order_guideline_service_point_and_action_buttons"
app:layout_constraintStart_toStartOf="parent"
android:layout_marginStart="8dp"
/>
<androidx.appcompat.widget.AppCompatSpinner
android:id="#+id/order_toolbar_service_point_spinner"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="#id/build_order_guideline_service_point_and_action_buttons"
app:layout_constraintStart_toEndOf="#id/order_service_point_spinner_label"
android:layout_marginEnd="8dp"/>
<androidx.constraintlayout.widget.Guideline
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/build_order_guideline_service_point_and_action_buttons"
app:layout_constraintGuide_percent="0.5"
/>
<TextView
android:id="#+id/order_textView_price"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:text="#{#string/currency_symbol + viewModel.price}"
android:textColor="#color/white"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#id/order_toolbar_button_more"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/build_order_guideline_service_point_and_action_buttons"
tools:text="$999.99"
/>
<Button
android:id="#+id/order_toolbar_button_more"
style="?android:attr/borderlessButtonStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="moreButtonAction"
android:text="#string/more"
android:textColor="#color/white"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#id/order_toolbar_button_send"
app:layout_constraintStart_toEndOf="#id/order_textView_price"
app:layout_constraintTop_toBottomOf="#id/build_order_guideline_service_point_and_action_buttons"/>
<Button
android:id="#+id/order_toolbar_button_send"
style="?android:attr/borderlessButtonStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="sendButtonAction"
android:text="#{viewModel.sendButtonText}"
android:textColor="#color/white"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#id/order_toolbar_button_more"
app:layout_constraintTop_toBottomOf="#+id/build_order_guideline_service_point_and_action_buttons"
tools:text="#string/send"/>
</androidx.constraintlayout.widget.ConstraintLayout>
<androidx.core.widget.ContentLoadingProgressBar
android:id="#+id/build_order_progress_bar"
style="?android:attr/progressBarStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:visibility="#{safeUnbox(viewModel.loading)}"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
/>
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
My Linear layout solution simply included replacing ConstraintLayout with a LinearLayout, removing all constraints from child elements and adding orientation: "vertical" (of course) plus putting layout_weight: 1 in the ViewPager element. If that helps anyone.

My guess is that you are using androidx.constraintlayout:constraintlayout:2.0.0-beta2.
This specific version is known to cause issues like this.
Update to the latest version ('androidx.constraintlayout:constraintlayout:2.0.0-beta6' at the time of writing).

goneMargin is not respected in a wrap_content ConstraintLayout?

I have a ConstraintLayout where its height is wrap_content.
I want its height to be able to collapse or expanding, according to its Child's height. Simple and common enough, right?
Now I have a layout which looks like this:
(First of all, please ignore the abnormal super large margin at the bottom. As you can see, the margin is just 16dp but the preview renders a very large margin.)
My problem is, if the big rectangle's visibility is set to gone,
According to the documentation of ConstraintLayout, if I set its goneMarginTop to a certainValue, it will retain that margin even when its visibility is gone. So that my Request Date will have some space to the bottom of parent.
However, this does not work as expected. Request Date sticked to the bottom of its parent:
(This is again a broken preview. In my real app, I am able to see a complete Request Date)
Have I done something wrong? Here is my complete code:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:background="#color/colorBasicGrey"
android:layout_marginBottom="2dp">
<View
android:id="#+id/item_indicator"
android:layout_width="8dp"
android:layout_height="8dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:background="#color/white"
android:layout_marginTop="24dp"
android:layout_marginLeft="24dp"/>
<TextView
android:id="#+id/group_member_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/group_member_join_group_request"
app:layout_constraintTop_toBottomOf="#id/item_indicator"
app:layout_constraintBottom_toTopOf="#id/item_indicator"
app:layout_constraintLeft_toRightOf="#id/item_indicator"
android:layout_marginLeft="8dp"
style="#style/general45"/>
<TextView
android:id="#+id/group_member_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
style="#style/general45"
android:textAllCaps="true"
app:layout_constraintBaseline_toBaselineOf="#id/group_member_label"
app:layout_constraintLeft_toLeftOf="parent"
android:layout_marginLeft="180dp"
tools:text="ABCDEFGHIJK"/>
<TextView
android:id="#+id/group_request_date_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/group_member_request_date_label"
app:layout_constraintTop_toBottomOf="#id/group_member_label"
app:layout_constraintLeft_toLeftOf="#id/group_member_label"
android:layout_marginTop="8dp"
style="#style/general45"/>
<TextView
android:id="#+id/group_request_date"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
style="#style/general45"
android:textAllCaps="true"
app:layout_constraintBaseline_toBaselineOf="#id/group_request_date_label"
app:layout_constraintLeft_toLeftOf="parent"
android:layout_marginLeft="180dp"
tools:text="28/10/2017"/>
<LinearLayout
android:id="#+id/admin_button_container"
android:layout_width="0dp"
android:layout_height="48dp"
android:layout_marginBottom="16dp"
android:layout_marginLeft="24dp"
android:layout_marginRight="24dp"
android:layout_marginTop="12dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#id/group_request_date_label"
app:layout_constraintVertical_bias="0.0"
app:layout_goneMarginTop="16dp"
app:layout_goneMarginLeft="24dp"
app:layout_goneMarginRight="24dp"
app:layout_goneMarginBottom="0dp"
android:visibility="gone">
<!--To simplify the question, I hided elements inside this LinearLayout-->
</LinearLayout>
</android.support.constraint.ConstraintLayout>

Figured it out.
goneMargin is used to indicate the margin to a GONE target, instead of itself being GONE.
Therefore in fact I should put the goneMargin attributes in the Request Date instead of the large rectangle.

Constraint Layout not working, maybe a bug in design editor?

I am creating my first app with android studio and this is my first problem:
I want to try the ConstraintLayout. I have built the layout with a ConstraintLayout with the Design Editor (clicking it together). When i try the layout in Android Emulator, all Buttons have moved in the left upper corner :(
Except the "Hello World" Label which was generated automatically when i created my first project.
The difference between the Label and the Button is, that some code lines beginning with app:layout_constraint.... are missing. You can see it in Code.
What am I doing wrong, or is it a bug?
I would be glad for an answer! :)
<?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="match_parent"
tools:context="com.example.u0017007.coffeecounter.MainActivity">
<TextView
android:layout_width="136dp"
android:layout_height="30dp"
android:text="Hello World!"
android:textSize="24sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.234" />
<Button
android:id="#+id/buttonAddCoffee"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:freezesText="false"
android:text="#string/add_coffee"
tools:layout_editor_absoluteX="16dp"
tools:layout_editor_absoluteY="231dp" />
<Button
android:id="#+id/buttonRemoveCoffee"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/remove_coffee"
tools:layout_editor_absoluteX="236dp"
tools:layout_editor_absoluteY="231dp" />
</android.support.constraint.ConstraintLayout>

tools:layout_editor_absoluteX and tools:layout_editor_absoluteY are only used for preview, like all tools:XXXX.
You need to add constraints to your view. You can add in the XML or you can do it with the visual editor.
There is a very good website that explain all about ConstraintsLayout.
By the way, Android Studio warm you with a error This view is not constrained, it only has designtime positions, so it will jump to (0,0) unless you add constraints if you don't set constraints.

It seems from the above code that, you didn't added any constraints to buttons thats why they moved to left upper corner.
<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="match_parent">
<TextView
android:layout_width="136dp"
android:layout_height="30dp"
android:text="Hello World!"
android:textSize="24sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.234" />
<Button
android:id="#+id/buttonAddCoffee"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:freezesText="false"
android:text="ADD coffee"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="276dp"
app:layout_constraintRight_toLeftOf="#+id/buttonRemoveCoffee"
android:layout_marginRight="82dp"
android:layout_marginLeft="24dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintHorizontal_bias="1.0" />
<Button
android:id="#+id/buttonRemoveCoffee"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="remove coffee"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="276dp"
android:layout_marginRight="24dp"
app:layout_constraintRight_toRightOf="parent" />
</android.support.constraint.ConstraintLayout>
Please refer to bellow link -
https://www.youtube.com/watch?v=z53Ed0ddxgM

tools:layout_editor_absoluteX="236dp"
tools:layout_editor_absoluteY="231dp"
These are used by studio to render in Graphic editor only. During run time,
as constraints are not set, the views take default position(0,0).
Try setting some constraints on buttons and procedd

UI too slow to be inflated, causing application to be slow

I have a constraint layout inside a ScrollView. This ConstraintLayout is supposed to be a parent for other Views that will be added into it, as shown:
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.constraint.ConstraintLayout
android:id="#+id/generated_main_constraint"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</android.support.constraint.ConstraintLayout>
When I try to add view to this ConstraintLayout, I inflate the view from XML, with the following code:
(ConstraintLayout) getLayoutInflater().inflate(R.layout.box_npcs, MAIN_CONSTRAINT, false);
This layout is defined in XML1 (end of the question).
Then I add TextViews with information to this Layout's LinearLayout, for that I use a programatically created TextView and add it into the layout
linearLayout.addView(new TextView("Foo"));
With that setup, I add this box to the main constraint layout.
The problem is: When I try to add more than 5 views, it takes a long time to proccess the UI, taking up to 5 seconds on the max amount of view to be added (50).
How can I add Complex Views to a ConstraintLayout in a way that it doesn't lag when trying to add the views?
XML1:
<?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/box_npcs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<ImageView
android:id="#+id/npcImage"
android:layout_width="88dp"
android:layout_height="88dp"
android:layout_marginBottom="0dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:scaleType="fitXY"
app:layout_constraintBottom_toBottomOf="#+id/layoutInformation"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="#+id/layoutInformation"
app:srcCompat="#drawable/camera" />
<android.support.constraint.ConstraintLayout
android:id="#+id/layoutInformation"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:maxWidth="280dp"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toRightOf="#+id/npcImage"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent">
<TextView
android:id="#+id/top_priority"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginRight="0dp"
android:layout_marginTop="0dp"
android:ellipsize="start"
android:text="DummyTextIsDummy"
android:textAppearance="#style/TextAppearance.AppCompat.Body1"
android:textColor="#color/common_google_signin_btn_text_light_default"
android:textSize="22sp"
android:textStyle="bold"
android:typeface="normal"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:ignore="HardcodedText" />
<LinearLayout
android:id="#+id/linearLayout_high_highest_normal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintLeft_toLeftOf="#+id/top_priority"
app:layout_constraintTop_toBottomOf="#+id/top_priority" />
</android.support.constraint.ConstraintLayout>
Images for examples:
Each 'box' in this screen is a box in the Main Constraint Layout.
Each TextLine is a different TextView added to the LinearLayout

What is the android version in your test device?
A few days ago, I found a problem.
If I use two or more ConstraintLayouts in Android 5 or 6, it will be slow.
When I used the Android Studio CPU Profiler, I saw the com.android.internal.policy.impl.phonewindow$decorview.onmeasure spent much time.
So I tried to use LinearLayout, and the problem was solved.
I think ConstraintLayout in Support Library is not friendly for Android 5 or 6.

Is this a bug at Android Studio?

I make UI of many buttons to input text by constraint layout.
For example, the following image.
But,I feel strange that android studio become very slow as I put more UIs and adaptive hook allows I set, sometimes disappear(ex.some buttons' allow disapper head row above image).It should use very large memory and I guess free memory to calculate position and re-render UI.
Can I avoid this situation? or Alternative way to make same UI using another layout. I'm very nervous for this problem because I can't understand the best way to make grid flexible-scaling UI.Any tips will help me.

I could solve the problem using grid layout enclosing the buttons nested constraint view and it seem best way that relative positioning UI.
<?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="match_parent">
<EditText
android:layout_width="456dp"
android:layout_height="64dp"
android:inputType="textPersonName"
android:text="Name"
android:ems="10"
android:id="#+id/editText"
android:layout_marginTop="16dp"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginStart="16dp"
app:layout_constraintLeft_toLeftOf="parent"
android:layout_marginEnd="16dp"
app:layout_constraintRight_toRightOf="parent" />
<GridLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:columnCount="8"
android:rowCount="5"
android:useDefaultMargins="true"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginBottom="32dp"
android:foregroundGravity="center_horizontal"
android:layout_marginStart="16dp"
app:layout_constraintLeft_toLeftOf="parent"
android:layout_marginEnd="16dp"
app:layout_constraintRight_toRightOf="parent"
android:layout_marginTop="8dp"
app:layout_constraintTop_toBottomOf="#+id/editText"
app:layout_constraintVertical_bias="0.81">
<Button
android:text="button"
android:layout_width="88dp"
android:background="#drawable/oval_btn"
android:id="#+id/str_wa"
android:layout_height="88dp"
tools:layout_editor_absoluteY="520dp"
tools:layout_editor_absoluteX="529dp" /> ・・・・・・
And you can place what you like.