androidx.preference.PreferenceScreen not found when creating Preferences screen

Question

After following this tutorial to create a screen for preferences, there seems to be a problem with inflating the class 'androidx.preference.PreferenceScreen'. Why is it not found when my preferences have been declared inside the res/xml folder and the necessary dependency has been added to this project?

My app's minSdkVersion is 24.

Error inflating class (not found)androidx.preference.PreferenceScreen

dependencies

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support:cardview-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:preference-v7:28.0.0'
    implementation 'com.android.support:recyclerview-v7:28.0.0'
    implementation 'com.android.support:support-v4:28.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

res/xml/preferences.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.preference.PreferenceScreen
    xmlns:android="http://schemas.android.com/apk/res/android">

    <CheckBoxPreference
        android:key="preference_a"
        android:defaultValue="false"
        android:title="Preference A" />

</androidx.preference.PreferenceScreen>

Activity layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/settings_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MySettingsActivity" />

Activity class

class MySettingsActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        supportFragmentManager
                .beginTransaction()
                .replace(R.id.settings_container, MySettingsFragment())
                .commit()
    }
}

Fragment class

class MySettingsFragment : PreferenceFragmentCompat() {
    override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
        addPreferencesFromResource(R.xml.app_preferences)
    }
}

Magnanimity

As of 2019/04/10, there is an obvious mistake in the settings tutorial. They forgot to call setContentView in the activity. – Acetum

Answer 1

If you're using AndroidX, you should update your dependencies:

implementation "androidx.legacy:legacy-preference-v14:1.0.0"
implementation "androidx.preference:preference:1.0.0"

The legacy is for the old com.android.support:preference-v14 while the other is for com.android.support:preference-v7.

If you don't use AndroidX but Android Support libraries, do not import AndroidX widgets into your XML.

Tolbutamide

My app's minSdkVersion is 24. Do I still need to use the legacy one? Please check my dependencies list. – Magnanimity

You're using an AndroidX widget in our XML yet your dependency is for a Support widget! – Tolbutamide

Ok. That's why, but this was not mentioned in the Android Developers tutorial. – Magnanimity

Answer 2

if you want to use PreferenceFragmentCompat first you need to implement the following dependency in you app level gradle.

implementation 'androidx.preference:preference:1.0.0

Stringency

Try to be more specific. Analyze your answer. – Feune

Answer 3

With support libraries 28.0.0 you should have XML code like this: (NOTE remove androidx for this case)

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:app="http://schemas.android.com/apk/res-auto">
    <CheckBoxPreference
        android:key="preference_a"
        android:defaultValue="false"
        android:title="Preference A" />
</PreferenceScreen>

and gradle config file:

implementation 'com.android.support:appcompat-v7:28.0.0'
implementation 'com.android.support:preference-v7:28.0.0'

and the implementation like this: (NOTE: set instead of add and rootKey):

public class SettingsFragment extends PreferenceFragmentCompat {

    public static final String TAG = SettingsFragment.class.getSimpleName();

    @Override
    public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
        setPreferencesFromResource(R.xml.preferences, rootKey);
    }
}

In the oficial documentation, they have androidx in the sample code, maybe that is the problem, you don't need it with support libraries

Rounder

Code needs to be in Kotlin NOT Java – Magnanimity

it's the same. Follow the link on the end. – Rounder

I’m using AndroidX for my project – Magnanimity