android custom notification not work with constraint layout

Question

I spend the whole day to figure out why my custom notifications are not being displayed. At the end, it was the problem with constraint layout. When I try to build custom_notification.xml with constraint layout the notification does not show up but if I change to linear layout the notification works. Can anybody tell me why this is happening?

custom_notitication.xml with linear layout (This layout works)

 <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:id="@+id/layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="8dp">
        <Button
            android:id="@+id/button"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:layout_marginTop="8dp"
            android:text="Button"

        <Button
            android:layout_weight="1"
            android:id="@+id/button2"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginTop="8dp"
            android:text="Button"

            />
    </LinearLayout>

custom_notitication.xml with Constraint Layout(this is not working)

<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:id="@+id/layout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="8dp">


    <Button
        android:id="@+id/button"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:text="Button"
        app:layout_constraintEnd_toStartOf="@+id/button2"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:layout_weight="1"
        android:id="@+id/button2"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:text="Button"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/button"
        />
</android.support.constraint.ConstraintLayout>

and kotlin code

  fun getNotification(context: Context): Notification {
        val mNotificationManager1: NotificationManager?

        val notification: Notification

        mNotificationManager1 = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
            createChannel(mNotificationManager1)

        val contentView = RemoteViews(applicationContext.packageName, R.layout.custom_notifaction)

        val mBuilder = NotificationCompat.Builder(applicationContext,"LockScreenTouch")
                .setSmallIcon(R.mipmap.ic_launcher)
                .setCustomBigContentView(contentView)
        notification = mBuilder.build()

        mNotificationManager1.notify(PostNotifactionActivity.ONGOING_NOTIFICATION_ID, notification)
        return notification
    }

    @TargetApi(26)
    @Synchronized
    private fun createChannel(notificationManager: NotificationManager?) {
        val name = "lockScreen"
        val importance = NotificationManager.IMPORTANCE_DEFAULT

        val mChannel = NotificationChannel("LockScreenTouch", name, importance)

        mChannel.enableLights(true)
        mChannel.lightColor = Color.BLUE
        notificationManager!!.createNotificationChannel(mChannel)
    }

and my buid.gradle

    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:support-v4:28.0.0'

Answer 1

Notification layouts use the RemoteViews implementation—the same as widgets.

There are very few Views that are compatible with RemoteViews. It's only a subset of the native/framework Views (ie no support Views, no library Views, no custom Views), and that subset isn't exhaustive:

• AdapterViewFlipper
• FrameLayout
• GridLayout
• GridView
• LinearLayout
• ListView
• RelativeLayout
• StackView
• ViewFlipper
• AnalogClock
• Button
• Chronometer
• ImageButton
• ImageView
• ProgressBar
• TextClock
• TextView

No other Views will work.

https://developer.android.com/reference/android/widget/RemoteViews