Develop Reference

Move view away from overlapping in ConstraintLayout (minimum constraint)

On some screens the text and image overlap. In that case I want to move the text upwards.
I place a TextView at a percentage position using a guideline. This is the preferred position of the text. Under it is an image with layout_width="match_parent" and ratio preserved. Depending on the screen aspect ratio, the image will become high enough to overlap with the text. In that case, I want the text to move upwards. So I want a "minimum constraint" of like 8dp between the text and image.
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.constraintlayout.widget.Guideline
android:id="#+id/guidelineGoldenRatio"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.381966" />
<TextView
android:id="#+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Keep me from overlapping"
app:layout_constraintTop_toTopOf="#+id/guidelineGoldenRatio"
app:layout_constraintBottom_toTopOf="#+id/guidelineGoldenRatio"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<ImageView
android:id="#+id/imageView"
android:layout_width="match_parent"
android:layout_height="0dp"
android:adjustViewBounds="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:srcCompat="#drawable/ic_supercat_popular" />
</androidx.constraintlayout.widget.ConstraintLayout>

You can use a Barrier widget. Set the barrier's diection to "Top" and set the reference ids to your image and the guideline. (If you can't reference the guideline, constrain a Space widget to the guideline and set the Space widget's id in the referenced ids of the barrier.)
Now constrain the text to the barrier with an 8dp margin. The text will now float with the barrier which will always be 8dp above the higher of the guideline and image.

Based on Cheticamp's answer:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.constraintlayout.widget.Guideline
android:id="#+id/guidelineGoldenRatio"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.381966" />
<androidx.constraintlayout.widget.Barrier
android:id="#+id/barrier"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:barrierDirection="top"
app:constraint_referenced_ids="imageView, guidelineGoldenRatio" />
<TextView
android:id="#+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Keep me from overlapping"
android:textSize="30dp"
app:layout_constraintBottom_toTopOf="#+id/barrier"
app:layout_constraintTop_toTopOf="#+id/barrier"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<ImageView
android:id="#+id/imageView"
android:layout_width="match_parent"
android:layout_height="0dp"
android:adjustViewBounds="true"
android:paddingTop="18dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:srcCompat="#drawable/ic_supercat_popular" />
</androidx.constraintlayout.widget.ConstraintLayout>
Note: the minimum distance between text and image goes into image padding. This padding should also compensate for half text height (when centering text vertically around guideline).

How about binding TextView to the Image, and setting padding simply? The image would be always screen-wide, and having a height that depends on the screen type - but the text would be always 8dp over the image.
<TextView
android:id="#+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Keep me from overlapping"
android:paddingBottom="8dp"
app:layout_constraintBottom_toTopOf="#+id/guidelineGoldenRatio"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<ImageView
android:id="#+id/imageView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:adjustViewBounds="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:srcCompat="#drawable/ic_supercat_popular" />

Why Android Constraint Baseline_toBaselineOf not working Vertically

<?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:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="#+id/playButton"
android:layout_width="73dp"
android:layout_height="62dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#android:drawable/ic_media_play" />
<ImageView
android:id="#+id/nextMusic"
android:layout_width="73dp"
android:layout_height="62dp"
android:layout_marginEnd="66dp"
app:layout_constraintStart_toEndOf="#+id/playButton"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="#+id/playButton"
app:layout_constraintBottom_toBottomOf="#+id/playButton"
app:layout_constraintBaseline_toBaselineOf="#+id/playButton"
app:srcCompat="#android:drawable/ic_media_next" />
<ImageView
android:id="#+id/previousMusic"
android:layout_width="73dp"
android:layout_height="62dp"
android:layout_marginStart="84dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/playButton"
app:layout_constraintBottom_toBottomOf="#+id/playButton"
app:layout_constraintBaseline_toBaselineOf="#+id/playButton"
app:srcCompat="#android:drawable/ic_media_previous" />
</androidx.constraintlayout.widget.ConstraintLayout>
I'm trying to align these three widgets by "app:layout_constraintBaseline_toBaselineOf", however, as shown on the result below, it does not seem to align properly:
How could I align them and send them to the screen bottom?

ImageViews don't have baselines, so remove all baseline constraints. Remove the app:layout_constraintTop_toTopOf="parent" constraint on the play button. This will send the play button to the bottom of the screen. (Constraining to the top and the bottom centers the widget.)
Once the play button is at the bottom, you can then adjust the other views. See the documentation for ConstraintLayout.

Why are the XML Elements not visible on my emulator in android studio?

My problem is that the controls (checkboxes, buttons etc) which I have placed are not visible on my emulator.
Below is my XML file:
<?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=".MainActivity">
<Button
android:id="#+id/btn1"
android:layout_width="match_parent"
android:layout_height="52dp"
android:text="#string/btn1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
tools:ignore="MissingConstraints"
tools:layout_editor_absoluteY="0dp" />
<Button
android:id="#+id/btn2"
android:layout_width="match_parent"
android:layout_height="77dp"
android:text="#string/btn2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
tools:ignore="MissingConstraints"
tools:layout_editor_absoluteY="68dp" />
<fragment
android:id="#+id/fragment"
android:name="com.example.mypc.fragmentactivity.Fragment1"
android:layout_width="222dp"
android:layout_height="285dp"
android:layout_marginBottom="40dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
tools:ignore="MissingConstraints" />
Here is my XML (design view):
Here is my emulator window:
Is there is something wrong in my XML file?
Please provide me solution for this.
How should I handle this?

You are using ConstraintLayout without relative positioning.
According to developer site:
Relative positioning is one of the basic building blocks of creating layouts in ConstraintLayout. Those constraints allow you to position a given widget relative to other. You can constrain a widget on the horizontal and vertical axis:
Horizontal Axis: left, right, start and end sides
Vertical Axis: top, bottom sides, and text baseline
Here is the solution which may help you:
<?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=".MainActivity">
<Button
android:id="#+id/btn1"
android:layout_width="match_parent"
android:layout_height="52dp"
android:text="#string/btn1"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toBottomOf="#id/btn2"/>
<Button
android:id="#+id/btn2"
android:layout_width="match_parent"
android:layout_height="77dp"
android:text="#string/btn2"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#id/btn1"
android:layout_marginTop="10dp"/>
</android.support.constraint.ConstraintLayout>
I have used relative positioning to solve the problem. If you are using constraint layout then without relative positioning your views will get overlap with each other.

Because you didn't align properly the second button. it seems like second button overlap first one.
try this one
<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=".activites.HomeActivity"
android:layout_margin="6dp">
<Button
android:id="#+id/btnOne"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:text="Button One"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/btnTwo"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:text="Button Two"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/btnOne" />
<fragment
android:id="#+id/fragment"
android:layout_width="222dp"
android:layout_height="285dp"
android:layout_marginBottom="40dp"
android:layout_marginTop="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/btnTwo"
tools:ignore="MissingConstraints" />
</android.support.constraint.ConstraintLayout>
output would be like this

In your code your elements are overflowing each other at one position that is why they are not visible.
My suggestion is do not constraint Layout at initial stage of learning android.
Use Linear Layout in place of constraint Layout.
Since in constraint Layout Layout Editor uses constraints to determine the position of a UI element within the layout. You have to give many constraint XML attributes like.
app:layout_editor_absoluteX="73dp"
app:layout_editor_absoluteY="176dp"
app:layout_constraintLeft_creator="1"
app:layout_constraintTop_creator="1"
app:layout_constraintRight_creator="1"
to specify the position of elements in layout.
Use Linear Layout in place of Constraint Layout and give
orientation:"vetical"
to view all your elements.

The layout_editor attributes are only used for the editor preview and have no effect on the final layouts. You should position your elements using the ConstraintLayout specific attributes.
It's used to just for preview purpose.
tools:layout_editor_absoluteY="68dp"

Simply use LinearLayout instead of ConstraintLayout. Also provide orientation vertical to that LinearLayout.
It will helps you
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
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"
android:orientation="vertical"
tools:context=".MainActivity">
<Button
android:id="#+id/btn1"
android:layout_width="match_parent"
android:layout_height="52dp"
android:text="#string/btn1" />
<Button
android:id="#+id/btn2"
android:layout_width="match_parent"
android:layout_height="77dp"
android:text="#string/btn2" />
<fragment
android:id="#+id/fragment"
android:name="com.example.mypc.fragmentactivity.Fragment1"
android:layout_width="222dp"
android:layout_height="285dp"
android:layout_marginBottom="40dp" />
</LinearLayout>

Constraint Layout Getting a default top margin for imageview

I am trying to create a layout using constraint layout, with an ImageView on top, a button in the ImageView, a TextView below it and then another TextView below it. Following is the xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
app:cardElevation="4dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#android:color/white">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="#+id/news_image1"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="16:9"
android:scaleType="centerCrop"
android:adjustViewBounds="true"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="0dp"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintBottom_toTopOf="#+id/news_title1"/>
<ImageButton
android:id="#+id/news_share_button_1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#android:color/transparent"
android:src="#drawable/share_button_big"
app:layout_constraintBottom_toBottomOf="#+id/news_image1"
app:layout_constraintRight_toRightOf="#+id/news_image1"
android:layout_marginRight="15dp"
android:layout_marginEnd="15dp"/>
<TextView
android:id="#+id/news_title1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:gravity="center_vertical|start"
android:layout_alignParentBottom="true"
android:lines="3"
android:ellipsize="end"
app:layout_constraintTop_toBottomOf="#+id/news_image1"
app:layout_constraintBottom_toTopOf="#+id/news_read_more1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:textColor="#color/colorPrimaryText"
android:layout_margin="#dimen/news_cell0_textview_margin"
android:textSize="12sp"
android:typeface="monospace" />
<TextView
android:id="#+id/news_read_more1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:gravity="center_vertical|start"
android:layout_alignParentBottom="true"
android:lines="1"
android:ellipsize="end"
app:layout_constraintTop_toBottomOf="#+id/news_title1"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
android:textColor="#color/read_more_text_color"
android:text="#string/news_read_more"
android:layout_margin="#dimen/news_cell0_textview_margin"
android:textSize="10sp" />
</android.support.constraint.ConstraintLayout>
</RelativeLayout>
</android.support.v7.widget.CardView>
Everything is correct except for a small margin on top of the first ImageView. Whatever I do I cannot get rid of that margin. See the image below.
Please note the margin between the top of the ImageView and the card, that is what is troubling me.

Your news_image, news_title1, and news_read_more1 views form a chain. Apparently, though I cannot find documentation on this, all views in a vertical chain will share vertical margins. In other words, applying a layout_marginTop or layout_marginBottom attribute to one of those three views will wind up applying it to all three of them.
You will have to re-allocate your margins, keeping this in mind.
Edit
Looks like the behavior is a little more sophisticated than I thought. First of all, it looks like it only applies to views with the spread "chain style" (which is the default). Second, it looks like top margin is applied to the view it is specified on as well as all views above that one in the chain, while bottom margin is applied to the view it is specified on as well as all views below that one in the chain. Finally, it appears that margins are cumulative (so if you had 10dp top margin on your bottom view and 20dp top margin on your middle view, the final result would be 30dp on your top view, 30dp on your middle view, and 10dp on your bottom view).
As for how to solve this problem in your specific case? You should be able to use left/right margins without issue. And then probably you should use bottom margin on your top view to space the three views out.
Edit #2
Muthukrishnan's answer made me realize that you could solve this problem by simply removing the chain from your views. If you delete the app:layout_constraintBottom_toTopOf="#+id/news_title1" constraint from your ImageView, that will break the chain and now the vertical margins aren't shared.

Thanks to the great starter by Ben P, I managed to figure out a solution. There are three(plus one weighed) chaining styles available in ConstraintLayout. According to this great tutorial the chaining styles are explained as:
Spread: The views are evenly distributed. E.g.
app:layout_constraintHorizontal_chainStyle=”spread”
app:layout_constraintVertical_chainStyle=”spread”
Spread inside: The first and last view are affixed to the constraints on each end of the chain and the rest are evenly distributed. E.g.
app:layout_constraintHorizontal_chainStyle=”spread_inside”
app:layout_constraintVertical_chainStyle=”spread_inside”
Packed: The views are packed together (after margins are accounted for). You can then adjust the whole chain’s bias (left/right or up/down) by changing the chain’s head view bias. E.g.
app:layout_constraintHorizontal_chainStyle=”packed”
app:layout_constraintVertical_chainStyle=”packed”
Weighted: When the chain is set to either spread or spread inside, you can fill the remaining space by setting one or more views to “match constraints” (0dp). By default, the space is evenly distributed between each view that's set to "match constraints," but you can assign a weight of importance to each view using thelayout_constraintHorizontal_weight and layout_constraintVertical_weight attributes. If you're familiar with layout_weight in a linear layout, this works the same way. So the view with the highest weight value gets the most amount of space; views that have the same weight get the same amount of space.
spread is the default chaining style. I changed it to spread_inside so that the first and last views are affixed to the constraints on each end of the chain(hence obeying the margins provided). The xml now looks like:
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
app:cardElevation="4dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#android:color/white">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="#+id/news_image1"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="16:9"
android:scaleType="centerCrop"
android:adjustViewBounds="true"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="0dp"
app:layout_constraintVertical_chainStyle="spread_inside"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintBottom_toTopOf="#+id/news_title1"/>
<ImageButton
android:id="#+id/news_share_button_1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#android:color/transparent"
android:src="#drawable/share_button_big"
app:layout_constraintBottom_toBottomOf="#+id/news_image1"
app:layout_constraintRight_toRightOf="#+id/news_image1"
android:layout_marginRight="15dp"
android:layout_marginEnd="15dp"/>
<TextView
android:id="#+id/news_title1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:gravity="center_vertical|start"
android:layout_alignParentBottom="true"
android:lines="3"
android:ellipsize="end"
app:layout_constraintVertical_chainStyle="spread_inside"
app:layout_constraintTop_toBottomOf="#+id/news_image1"
app:layout_constraintBottom_toTopOf="#+id/news_read_more1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:textColor="#color/colorPrimaryText"
android:layout_margin="#dimen/news_cell0_textview_margin"
android:textSize="12sp"
android:typeface="monospace" />
<TextView
android:id="#+id/news_read_more1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:gravity="center_vertical|start"
android:layout_alignParentBottom="true"
android:lines="1"
android:ellipsize="end"
app:layout_constraintVertical_chainStyle="spread_inside"
app:layout_constraintTop_toBottomOf="#+id/news_title1"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
android:textColor="#color/read_more_text_color"
android:text="#string/news_read_more"
android:layout_margin="#dimen/news_cell0_textview_margin"
android:textSize="10sp" />
</android.support.constraint.ConstraintLayout>
</RelativeLayout>
</android.support.v7.widget.CardView>

Try this, I remove app:layout_constraintTop_toTopOf="parent" in your layout it works
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
app:cardElevation="4dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/white">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="#+id/news_image1"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="16:9"
android:scaleType="centerCrop"
android:adjustViewBounds="true"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toLeftOf="parent"/>
<ImageButton
android:id="#+id/news_share_button_1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#android:color/transparent"
android:src="#drawable/ic_menu_share"
app:layout_constraintBottom_toBottomOf="#+id/news_image1"
app:layout_constraintRight_toRightOf="#+id/news_image1"
android:layout_marginRight="15dp"
android:layout_marginEnd="15dp"/>
<AliasTextView
android:id="#+id/news_title1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:gravity="center_vertical|start"
android:layout_alignParentBottom="true"
android:lines="3"
android:ellipsize="end"
app:layout_constraintTop_toBottomOf="#+id/news_image1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:textColor="#color/colorPrimaryText"
android:layout_margin="#dimen/news_cell0_textview_margin"
android:textSize="12sp"
android:typeface="monospace" />
<TextView
android:id="#+id/news_read_more1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:gravity="center_vertical|start"
android:layout_alignParentBottom="true"
android:lines="1"
android:ellipsize="end"
app:layout_constraintTop_toBottomOf="#+id/news_title1"
app:layout_constraintLeft_toLeftOf="parent"
android:textColor="#color/read_more_text_color"
android:text="#string/news_read_more"
android:layout_margin="#dimen/news_cell0_textview_margin"
android:textSize="10sp" />
</android.support.constraint.ConstraintLayout>
</RelativeLayout>
</android.support.v7.widget.CardView>

app:layout_marginBottom is not working well with android constraint layout

Is there any reason why the following layout_marginBottom is not working?
However, if I use layout_marginTop on the second view it does work well
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ade4ad">
<TextView
android:id="#+id/first"
android:layout_width="90dp"
android:layout_height="40dp"
app:layout_marginBottom="10dp"
android:background="#000"/>
<TextView
android:id="#+id/second"
android:layout_width="90dp"
android:layout_height="40dp"
android:background="#fff"
app:layout_constraintTop_toBottomOf="#+id/first"/>
</android.support.constraint.ConstraintLayout>

In order to
android:layout_marginBottom="20dp"
work well, you should use
app:layout_constraintBottom_toBottomOf="parent"

Layout top/bottom margin works only when:
constraints in the same direction need to connect with their next neighbor child, like a unidirectional linked list.
last constraint in the direction must be set.
In your case, you need to set "layout_constraintBottom_toXXXXX" for each view in the chain, and last view set bottom to parent.
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#ade4ad">
<TextView
android:id="#+id/first"
android:layout_width="90dp"
android:layout_height="40dp"
app:layout_marginBottom="10dp"
app:layout_constraintBottom_toTopOf="#+id/second"
android:background="#000"/>
<TextView
android:id="#+id/second"
android:layout_width="90dp"
android:layout_height="40dp"
app:layout_marginBottom="10dp"
app:layout_constraintBottom_toTopOf="#+id/third"
android:background="#fff"/>
<TextView
android:id="#+id/third"
android:layout_width="90dp"
android:layout_height="40dp"
android:background="#fff"
app:layout_constraintBottom_toBottomOf="parent"/>
</android.support.constraint.ConstraintLayout>
Moreover, reverse dependency is not required except you want "layout_marginTop" works.

you can use that trick, create a space bellow, align to parent bottom
<Space
android:id="#+id/space"
android:layout_width="wrap_content"
android:layout_height="80dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
and align your view on top of the space
app:layout_constraintBottom_toTopOf="#+id/space"
like so
<TextView
android:id="#+id/howNext"
style="#style/white_action_btn_no_border"
android:layout_width="344dp"
android:layout_height="60dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:text="#string/got_it_next"
app:layout_constraintBottom_toTopOf="#+id/space"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />

This is not LinearLayout or RelativeLayout, its ConstraintLayout so you have to give Left, Right, Bottom, Top Constraint to Relevant Layout, in your case You have to give TextView first Bottom_Top Constraint to TextView second. so you can get Margin between Two TextView.
Your layout should be like below.
<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"
android:background="#ade4ad">
<TextView
android:id="#+id/first"
android:layout_width="90dp"
android:layout_height="40dp"
android:background="#000"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toLeftOf="parent" />
<TextView
android:id="#+id/second"
android:layout_width="90dp"
android:layout_height="40dp"
android:background="#fff"
android:layout_marginTop="10dp"
app:layout_constraintTop_toBottomOf="#+id/first"
app:layout_constraintLeft_toLeftOf="#+id/first"
app:layout_constraintRight_toRightOf="#+id/first" />
</android.support.constraint.ConstraintLayout>