[DatePicker] Fix NullPointerException on MonthAdapter.updateSelectedS…

…tate(MonthAda…

Resolves #1944
Resolves #1943

GIT_ORIGIN_REV_ID=d02d6307ea08ea505ea6535ce909e7d1b268847b
PiperOrigin-RevId: 350783859

(cherry picked from commit 00e3320)

lib/java/com/google/android/material/datepicker/MonthAdapter.java

@@ -133,7 +133,8 @@ public TextView getView(int position, @Nullable View convertView, @NonNull ViewG
     if (date == null) {
       return day;
     }
-    return updateSelectedState(day, date);
+    updateSelectedState(day, date);
+    return day;
   }
 
   public void updateSelectedStates(MaterialCalendarGridView monthGrid) {
@@ -161,28 +162,34 @@ private void updateSelectedStateForDate(MaterialCalendarGridView monthGrid, long
     }
   }
 
-  private TextView updateSelectedState(TextView day, long date) {
+  private void updateSelectedState(@Nullable TextView day, long date) {
+    if (day == null) {
+      return;
+    }
+    final CalendarItemStyle style;
     if (calendarConstraints.getDateValidator().isValid(date)) {
       day.setEnabled(true);
-      for (long selectedDay : dateSelector.getSelectedDays()) {
-        if (UtcDates.canonicalYearMonthDay(date) == UtcDates.canonicalYearMonthDay(selectedDay)) {
-          calendarStyle.selectedDay.styleItem(day);
-          return day;
-        }
-      }
-
-      if (UtcDates.getTodayCalendar().getTimeInMillis() == date) {
-        calendarStyle.todayDay.styleItem(day);
-        return day;
+      if (isSelected(date)) {
+        style = calendarStyle.selectedDay;
+      } else if (UtcDates.getTodayCalendar().getTimeInMillis() == date) {
+        style = calendarStyle.todayDay;
       } else {
-        calendarStyle.day.styleItem(day);
-        return day;
+        style = calendarStyle.day;
       }
     } else {
       day.setEnabled(false);
-      calendarStyle.invalidDay.styleItem(day);
-      return day;
+      style = calendarStyle.invalidDay;
+    }
+    style.styleItem(day);
+  }
+
+  private boolean isSelected(long date) {
+    for (long selectedDay : dateSelector.getSelectedDays()) {
+      if (UtcDates.canonicalYearMonthDay(date) == UtcDates.canonicalYearMonthDay(selectedDay)) {
+        return true;
+      }
     }
+    return false;
   }
 
   private void initializeStyles(Context context) {