Android checkbox not inflated as MaterialCheckBox as stated in documentation

Question

I'm trying to following the documentation from Material 3 for checkboxes: https://github.com/material-components/material-components-android/blob/master/docs/components/Checkbox.md

At the very beginning it states:

Note: <CheckBox> is auto-inflated as <com.google.android.material.button.MaterialCheckBox> via MaterialComponentsViewInflater when using a Theme.Material3.* theme.

This does not seem to work for me, can someone please explain why the checkbox is not auto-inflated as a MaterialCheckBox?

Both theme files are using: Theme.Material3.*

<resources xmlns:tools="http://schemas.android.com/tools">
    <!-- Base application theme. -->
    <style name="Theme.ParentChildCheckboxes" parent="Theme.Material3.Light.NoActionBar">
        <!-- Primary brand color. -->
        <item name="colorPrimary">@color/purple_500</item>
        <item name="colorPrimaryVariant">@color/purple_700</item>
        <item name="colorOnPrimary">@color/white</item>
        <!-- Secondary brand color. -->
        <item name="colorSecondary">@color/teal_200</item>
        <item name="colorSecondaryVariant">@color/teal_700</item>
        <item name="colorOnSecondary">@color/black</item>
        <!-- Status bar color. -->
        <item name="android:statusBarColor">?attr/colorPrimaryVariant</item>
        <!-- Customize your theme here. -->
    </style>
</resources>

<resources xmlns:tools="http://schemas.android.com/tools">
    <!-- Base application theme. -->
    <style name="Theme.ParentChildCheckboxes" parent="Theme.Material3.Dark.NoActionBar">
        <!-- Primary brand color. -->
        <item name="colorPrimary">@color/purple_200</item>
        <item name="colorPrimaryVariant">@color/purple_700</item>
        <item name="colorOnPrimary">@color/black</item>
        <!-- Secondary brand color. -->
        <item name="colorSecondary">@color/teal_200</item>
        <item name="colorSecondaryVariant">@color/teal_200</item>
        <item name="colorOnSecondary">@color/black</item>
        <!-- Status bar color. -->
        <item name="android:statusBarColor">?attr/colorPrimaryVariant</item>
        <!-- Customize your theme here. -->
    </style>
</resources>

Layout file:

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

    <CheckBox
        android:id="@+id/checkbox_parent"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/label_parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <CheckBox
        android:id="@+id/checkbox_child_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="@string/label_child_1"
        app:layout_constraintStart_toStartOf="@+id/checkbox_parent"
        app:layout_constraintTop_toBottomOf="@+id/checkbox_parent" />

    <CheckBox
        android:id="@+id/checkbox_child_2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="@string/label_child_2"
        app:layout_constraintStart_toStartOf="@+id/checkbox_parent"
        app:layout_constraintTop_toBottomOf="@+id/checkbox_child_1" />


    <CheckBox
        android:id="@+id/checkbox_child_3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="@string/label_child_3"
        app:layout_constraintStart_toStartOf="@+id/checkbox_parent"
        app:layout_constraintTop_toBottomOf="@+id/checkbox_child_2" />

    <CheckBox
        android:id="@+id/checkbox_child_4"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="@string/label_child_4"
        app:layout_constraintStart_toStartOf="@+id/checkbox_parent"
        app:layout_constraintTop_toBottomOf="@+id/checkbox_child_3" />

</androidx.constraintlayout.widget.ConstraintLayout>

Activity file:

package com.example.parentchildcheckboxes

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import com.example.parentchildcheckboxes.databinding.ActivityMainBinding
import com.google.android.material.checkbox.MaterialCheckBox.STATE_INDETERMINATE

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        val checkBoxParent = binding.checkboxParent
        checkBoxParent.checkedState = STATE_INDETERMINATE
    }
}

I cant use .checkedState on checkBoxParent because it's not treated as a MaterialCheckBox:

When I hover on the val checkBoxParent , I see: val checkBoxParent: CheckBox and expected: val checkBoxParent: MaterialCheckBox.

When I change: val checkBoxParent = binding.checkboxParent to: val checkBoxParent = binding.checkboxParent as MaterialCheckBox:

    val checkBoxParent = binding.checkboxParent as MaterialCheckBox
    checkBoxParent.checkedState = STATE_INDETERMINATE

it works fine.

Why is the checkbox not auto-inflated as a MaterialCheckBox? as stated in the documentation?

Answer 1

Changing the <CheckBox> tag to: <com.google.android.material.checkbox.MaterialCheckBox> solved the issue for me:

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

    <com.google.android.material.checkbox.MaterialCheckBox
        android:id="@+id/checkbox_parent"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/label_parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.checkbox.MaterialCheckBox
        android:id="@+id/checkbox_child_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="@string/label_child_1"
        app:layout_constraintStart_toStartOf="@+id/checkbox_parent"
        app:layout_constraintTop_toBottomOf="@+id/checkbox_parent" />

    <com.google.android.material.checkbox.MaterialCheckBox
        android:id="@+id/checkbox_child_2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="@string/label_child_2"
        app:layout_constraintStart_toStartOf="@+id/checkbox_parent"
        app:layout_constraintTop_toBottomOf="@+id/checkbox_child_1" />

    <com.google.android.material.checkbox.MaterialCheckBox
        android:id="@+id/checkbox_child_3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="@string/label_child_3"
        app:layout_constraintStart_toStartOf="@+id/checkbox_parent"
        app:layout_constraintTop_toBottomOf="@+id/checkbox_child_2" />

    <com.google.android.material.checkbox.MaterialCheckBox
        android:id="@+id/checkbox_child_4"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="@string/label_child_4"
        app:layout_constraintStart_toStartOf="@+id/checkbox_parent"
        app:layout_constraintTop_toBottomOf="@+id/checkbox_child_3" />

</androidx.constraintlayout.widget.ConstraintLayout>