ConstraintLayout layout_constraintHorizontal_bias seems not work
Try this
<?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">
<EditText
android:id="@+id/editText2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="16dp"
android:ems="10"
android:hint="please input test content"
android:inputType="phone"
android:textColorHint="@android:color/holo_red_light"
android:textSize="13sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<TextView
android:layout_width="80dp"
android:layout_height="50dp"
android:gravity="center"
android:text="Hello"
android:textColor="@android:color/black"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
EDIT
to use bias
you need to give constrained it to any parent.
Try this:
app:layout_constraintHorizontal_bias="0.5"
is not working because you haven't constrained it to any parent. Read more about bias.
<?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:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="80dp"
android:layout_height="50dp"
android:gravity="center"
android:text="Hello"
android:textColor="@android:color/black"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="@+id/editText2"
android:layout_width="150dp"
android:layout_height="50dp"
android:layout_marginBottom="16dp"
android:ems="10"
android:hint="please input test content"
android:inputType="phone"
android:textColorHint="@android:color/holo_red_light"
android:textSize="13sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>