Rendering Issue in Android Studio

Question

I am new to Android Studio.And I came accross this problem under activity_main.xml tab . So, How to fix this.I have installed the android studio 1.4.1 bundle offline. Also I can't drag and drop widgets to phone in activity_main.xml.But I can drag and drop in content_main.xml

 Rendering Problems
 The following classes could not be instantiated:
- android.support.design.widget.CoordinatorLayout (Open Class, Show Exception, Clear Cache)
- android.support.design.widget.AppBarLayout (Open Class, Show Exception, Clear Cache)
 Tip: Use View.isInEditMode() in your custom views to skip code or show sample data when shown in the IDE 

Exception Details  

 java.lang.IllegalArgumentException: You need to use a Theme.AppCompat theme (or descendant) with the design library.  
 at android.support.design.widget.ThemeUtils.checkAppCompatTheme(ThemeUtils.java:34)  
 at android.support.design.widget.CoordinatorLayout.<init>(CoordinatorLayout.java:178)   
 at android.support.design.widget.CoordinatorLayout.<init>(CoordinatorLayout.java:172)  
 at java.lang.reflect.Constructor.newInstance(Constructor.java:422)   
 at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)   
 at android.view.LayoutInflater.inflate(LayoutInflater.java:492)   
 at android.view.LayoutInflater.inflate(LayoutInflater.java:394) 
  Copy stack to clipboard

Here is my activity_main.xml in text

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.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" android:fitsSystemWindows="true"
tools:context=".MainActivity">

<android.support.design.widget.AppBarLayout android:layout_height="wrap_content"
    android:layout_width="match_parent" android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.v7.widget.Toolbar android:id="@+id/toolbar"
        android:layout_width="match_parent" android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay" />

</android.support.design.widget.AppBarLayout>

<android.support.design.widget.FloatingActionButton android:id="@+id/fab"
    android:layout_width="wrap_content" android:layout_height="wrap_content"
    android:layout_gravity="bottom|end" android:layout_margin="@dimen/fab_margin"
    android:src="@android:drawable/ic_dialog_email" />
   </android.support.design.widget.CoordinatorLayout>

Answer 1

Since your MainActivity extends AppCompatActivity, its theme most be from AppCompat. To fix this issue, correct the following:

1. Open the file app/res/values/styles.xml
2. Change the following lines in the styles.xml file to look like this:

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">

<style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />

and

<style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />.

They all need to inherit from AppCompat for your chosen layout. See the default working styles.xml file below. You can copy and paste it into your styles.xml file.

<resources>
    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>
    <style name="AppTheme.NoActionBar">
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>
    </style>
    <style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />
    <style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />
</resources>

3. If you are still having issues, go to the app/manifests/AndroidManifest.xml file and make sure that the value for the theme looks like this android:theme="@style/AppTheme.NoActionBar" or this android:theme="@style/AppTheme" this way they are inheriting from the AppCompat themes as listed above.

See here as well: You need to use a Theme.AppCompat theme (or descendant) with this activity

Answer 2

The parent of AppTheme need is child or Theme.AppCompat . Pls check style: @style/AppTheme in your code