Title: Blank design tab in android studio
Tags: android-studio
Question: https://imgur.com/a/arLyGYR
The design tab for my Android Studio doesn't display even the starting Hello World or my project name,  does anybody know how to make this display and update as I write my program ?
edit:  I'm not sure how the code will help, the tutorial im following says that the design tab should look like this upon opening https://imgur.com/a/FRgc2G1 and update as I code.  I think it's a problem with the settings of android studio because the only code i've changed is what they have told me to.
<?xml version="1.0" encoding="utf-8"?&gt;
<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="#0d7429"
tools:context=".MainActivity"
tools:layout_editor_absoluteY="25dp"&gt;
<android.support.v7.widget.AppCompatTextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@color/colorPrimaryDark"
android:text="@string/Hello_World_Text"
android:textColor="@android:color/white"
android:textSize="30sp"
app:fontFamily="cursive" /&gt;
</android.support.constraint.ConstraintLayout&gt;
Comment: With images we can only see the result, not what may have caused the result. Code is much more useful here.

Comment: Add code instead of images so we can help.

Here is the accepted answer: It is because  you have an error in your xml.
Changing TextView to android.support.v7.widget.AppCompatTextView works if you want to use "app" name space prefix for app:fontFamily. However,you can also use android namespace prefix  for fontFamily but it is only compatible with API version 16 and higher.
Comment for this answer: I have changed it and tried both multiple times but my design is still the first picture I linked above  (i updated the code to the new code)
Comment for this answer: The text tab just shows me all of my code, I only see the result when I run the emulator
Comment for this answer: I can drag a button onto the design preview and the button shows up under the constraint layout as an object, but there is no visible button
Comment for this answer: My preview is still default and doesn't have the text or background or buttons or anything https://imgur.com/a/pOobaEs
Comment for this answer: Is it showing a preview when you switch to the TEXT tab?
Comment for this answer: preview is on the right top corner of the text tab [image](https://imgur.com/a/0TZbIid)
Comment for this answer: There will probably be a tiny,red (!) exclamation mark in the preview .click on it and post what does it say
Comment for this answer: yes there is that exclamation mark, click on it and it will tell you the problem.Then you can update your question with the error

Here is another answer: go to app/res/values/styles.xml
if it says:
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar"&gt;
change it to
<style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar"&gt;
Comment for this answer: Why should that be changed? What is the reason the former value doesn't work?

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