我的问题是使用FragmentActivity。我切换到AppCompatActivity，它对我很有效。

验证码：

public class MainActivity extends AppCompatActivity implements DatePickerDialog.OnDateSetListener{
        TextView textView;
        Button txt_open_date_picker;
        int yy,mm,dd;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            textView = findViewById(R.id.text);
            txt_open_date_picker = (Button) findViewById(R.id.txt_open_date_picker);
    
            txt_open_date_picker.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    DatePickerDialog datePickerDialog = new DatePickerDialog(
                            MainActivity.this,
                            MainActivity.this,
                            Calendar.getInstance().get(Calendar.YEAR),
                            Calendar.getInstance().get(Calendar.MONTH),
                            Calendar.getInstance().get(Calendar.DAY_OF_MONTH));
    
                    datePickerDialog.show();
                }
            });
    
        }
    
        @Override
        public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
            String date = dayOfMonth + "/" + month + "/" + year;
            textView.setText(date);
        }
    }

您可以按如下方式对齐所选文本：

<style name="MyCustomMaterialDatePicker" parent="ThemeOverlay.MaterialComponents.MaterialCalendar">
    <item name="materialCalendarHeaderSelection">@style/MaterialCalendar.HeaderSelection</item>
</style>

  <style name="MaterialCalendar.HeaderSelection" parent="@style/Widget.MaterialComponents.MaterialCalendar.HeaderSelection">
    <item name="android:layout_gravity">start|bottom</item>
</style>

然后在科廷

MaterialDatePicker.Builder.datePicker().setTheme(R.style.MyCustomMaterialDatePicker)