You can change your selected date color with create a selector.
create a selector file: your_selector.xml
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_activated="true" android:color="@color/white" />
<item android:color="@color/color_black" />
</selector>
Use your selector in style :
<style name="CalenderViewDateCustomText">
<item name="colorControlNormal">@color/white</item>
<item name="colorControlActivated">@color/white</item>
<item name="colorControlHighlight">@color/white</item>
<item name="android:textColor">@drawable/your_selector</item>
</style>
use it in calender view :
<CalendarView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/CalenderViewCustom"
android:dateTextAppearance="@style/CalenderViewDateCustomText"
android:weekDayTextAppearance="@style/CalenderViewWeekCustomText"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
calendar example