Question: I'm looking for changing the **TextView** Sizes automatically. And I found the solution as well. Here is the official [Doc](https://developer.android.com/preview/features/autosizing-textview.html) for Auto sizing textviews. But Still I'm not able to resolve it. When i paste autoSizeTextType its showing error in xml file.

Here is the my xml code and gradle code snippets

myactivity.xml

```
<?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:background="@color/white"
    android:orientation="vertical">

<include layout="@layout/toolbar" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:autoSizeTextType="uniform"/>

</LinearLayout>

```

Gradle snippet

```
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
    exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:support-v4:25.2.0'//Added support library
    compile 'com.android.support:appcompat-v7:25.2.0'
    compile 'com.android.support:design:25.2.0'
    testCompile 'junit:junit:4.12'
}

```

Answer: 
As stated in the [docs](https://developer.android.com/guide/topics/ui/look-and-feel/autosizing-textview.html#setting-textview-autosize): 

> 
> The Support Library 26.0 provides full support to the autosizing TextView feature on devices running Android versions prior to Android 8.0 (API level 26). The library provides support to Android 4.0 (API level 14) and higher. **The android.support.v4.widget package contains the TextViewCompat** class to access features in a backward-compatible fashion.
> 
> 
> 

You need to replace `TextView` with `AppCompatTextView` and upgrade your support lib to v26.0.0 in order to use that feature. 

```
compile 'com.android.support:support-v4:26.0.0'

```

Don't forget to upgrade your `buildToolsVersion` to `26.0.0` and `compileSdkVersion` to `26` as well.
This API is available only from API level 26.