Can't Use Autosizing Textview with Support Library

Question

I have the following text view, which is supposed to contain auto sizing text.

<TextView
    android:layout_width="0dp"
    android:layout_height="200dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintTop_toBottomOf="@id/tabRecyclerView"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    android:background="@color/lightshade"
    android:text="@string/add_favorites_message"
    android:gravity="center"
    android:minLines="2"
    android:maxLines="2"
    app:autoSizeTextType="uniform"/>

However, I am getting the error "unexpected namespace prefix "app"" in reference to the last line.

I find this odd because I am using the following support libraries in my build.gradle:

implementation 'com.android.support:support-v4:27.1.1'
implementation 'com.android.support:appcompat-v7:27.1.1'
implementation 'com.android.support.constraint:constraint-layout:1.1.0'
implementation 'com.android.support:recyclerview-v7:27.1.1'

I'm using this documentation as my guide.

What am I doing wrong?

Here is the full layout:

<?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="250dp"
    tools:context=".MainActivity">


    <android.support.v7.widget.RecyclerView
        android:id="@+id/tabRecyclerView"
        android:layout_width="0dp"
        android:layout_height="50dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toTopOf="@id/imageRecyclerView"
        app:layout_constraintTop_toTopOf="parent" />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/imageRecyclerView"
        android:layout_width="0dp"
        android:layout_height="200dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@id/tabRecyclerView"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        android:background="@color/lightshade"
        />

    <TextView
        android:id="@+id/add_favorites_message"
        android:layout_width="0dp"
        android:layout_height="200dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@id/tabRecyclerView"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        android:background="@color/lightshade"
        android:text="@string/add_favorites_message"
        android:visibility="gone"
        android:gravity="center"
        android:minLines="2"
        android:maxLines="2" />


</android.support.constraint.ConstraintLayout>

Do you have any other Layout enclosing your TextView and inside your ConstraintLayout where you have delcared xmlns:app="http://schemas.android.com/apk/res-auto" ? — Facundo Larrosa, Jun 04 '18 at 22:33
I'll post the full layout, but I believe not. I don't think the problem is with the app prefix itself, because the other "app" prefixes work fine. The only one that is problematic is the one on the bottom line of the `TextView` that enables auto resizing text. — Roymunson, Jun 04 '18 at 22:36
It's really awkward. I know it may be a silly suggestion but, have you tried cleaning and rebuilding your project? — Facundo Larrosa, Jun 04 '18 at 22:42
A more detailed log of the error then... If you want, just trying to help! — Facundo Larrosa, Jun 04 '18 at 23:03
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/172453/discussion-between-roymunson-and-facundo). — Roymunson, Jun 04 '18 at 23:22

score 1 · Accepted Answer · answered Jun 04 '18 at 23:28

I had to change the TextView to:

<android.support.v7.widget.AppCompatTextView
    android:id="@+id/add_favorites_message"
    android:layout_width="0dp"
    android:layout_height="200dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintTop_toBottomOf="@id/tabRecyclerView"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:autoSizeTextType="uniform"
    android:background="@color/lightshade"
    android:text="@string/add_favorites_message"
    android:visibility="gone"
    android:gravity="center"
    android:lines="2"
    />

This answer doesn't make sense to me because the first answer in this post, says I shouldn't have to do this. But at least the error is gone.

Can't Use Autosizing Textview with Support Library

1 Answers1