实现DatePicker类时如何在OnDateSet方法中更新UI？

Question

我有DatePicker类，如：

package datepicker;

import android.app.DatePickerDialog;
import android.content.Context;
import android.text.InputType;
import android.text.format.DateFormat;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.EditText;

import com.marknguyen.babygenderpredictor.TimePredictorActivity;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

import sola2lunar.Lunar;
import sola2lunar.LunarSolarConverter;
import sola2lunar.Solar;

public class DatePicker extends EditText implements DatePickerDialog.OnDateSetListener {
    public interface OnDateSetListener {
        public void onDateSet(DatePicker view, int year, int month, int day);
    }
    private Lunar lunarBirthday;
    private Lunar lunarCurrent;
    protected int year;
    protected int month;
    protected int day;
    protected long maxDate = -1;
    protected long minDate = -1;
    protected OnDateSetListener onDateSetListener = null;
    protected java.text.DateFormat dateFormat;

    public OnDateSetListener getOnDateSetListener() {
        return onDateSetListener;
    }

    public void setOnDateSetListener(OnDateSetListener onDateSetListener) {
        this.onDateSetListener = onDateSetListener;
    }

    public DatePicker(Context context, AttributeSet attrs) {
        super(context, attrs);

        dateFormat = DateFormat.getMediumDateFormat(getContext());

        setInputType(InputType.TYPE_DATETIME_VARIATION_DATE);
        setFocusable(false);
        setToday();
    }

    public int getYear() {
        return year;
    }

    public void setYear(int year) {
        this.year = year;
        updateText();
    }

    public int getMonth() {
        return month;
    }

    public void setMonth(int month) {
        this.month = month;
        updateText();
    }

    public int getDay() {
        return day;
    }

    public void setDay(int day) {
        this.day = day;
        updateText();
    }

    public void setDate(int year, int month, int day) {
        this.year = year;
        this.month = month;
        this.day = day;

        updateText();
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if(event.getAction() == MotionEvent.ACTION_DOWN)
            showDatePicker();

        return super.onTouchEvent(event);
    }

    public java.text.DateFormat getDateFormat() {
        return dateFormat;
    }

    public void setDateFormat(java.text.DateFormat dateFormat) {
        this.dateFormat = dateFormat;
        updateText();
    }

    public void setMaxDate(int year, int month, int day) {
        Calendar c = Calendar.getInstance();
        c.set(year, month, day, 23, 59, 59);
        this.maxDate = c.getTimeInMillis();
    }

    public void setMinDate(int year, int month, int day) {
        Calendar c = Calendar.getInstance();
        c.set(year, month, day, 0, 0, 0);
        this.minDate = c.getTimeInMillis();
    }

    public void setToday() {
        Calendar c = Calendar.getInstance();
        setDate(c.get(Calendar.YEAR), c.get(Calendar.MONTH), c.get(Calendar.DAY_OF_MONTH));
    }

    protected void showDatePicker() {
        DatePickerDialog datePickerDialog;

        datePickerDialog = new DatePickerDialog(
                getContext(),
                this,
                getYear(),
                getMonth(),
                getDay());

        if (this.maxDate != -1) {
            datePickerDialog.getDatePicker().setMaxDate(maxDate);
        }
        if (this.minDate != -1) {
            datePickerDialog.getDatePicker().setMinDate(minDate);
        }

        datePickerDialog.show();
    }

    @Override
    public void onDateSet(android.widget.DatePicker view, int year,
            int monthOfYear, int dayOfMonth) {
        setDate(year, monthOfYear, dayOfMonth);
        clearFocus();

        Solar solar = new Solar();
        solar.solarYear = year;
        solar.solarMonth = monthOfYear+1;
        solar.solarDay = dayOfMonth;
        lunarBirthday = LunarSolarConverter.SolarToLunar(solar);

        String currentDate = new SimpleDateFormat("yyyy-MM-dd").format(new Date());
        String[] curr = currentDate.split("-");
        Solar solar_curr = new Solar();
        solar_curr.solarDay = Integer.parseInt(curr[2]);
        solar_curr.solarMonth = Integer.parseInt(curr[1]);
        solar_curr.solarYear = Integer.parseInt(curr[0]);
        lunarCurrent = LunarSolarConverter.SolarToLunar(solar_curr);

        TimePredictorActivity.ageMom = lunarCurrent.lunarYear - lunarBirthday.lunarYear;

        TimePredictorActivity.tv_lunarAge.setText("Lunar age: " + TimePredictorActivity.ageMom);
//      if(onDateSetListener != null)
//          onDateSetListener.onDateSet(this, year, month, day);
    }

    public void updateText() {
        Calendar cal = new GregorianCalendar(getYear(), getMonth(), getDay());
        setText(dateFormat.format(cal.getTime()));
    }
}

在MainActivity扩展DatePicker课程中。我必须覆盖OnDateSet()方法，以便如何在TextView onDateSet()方法中更新MainActivity等用户界面？调试后，它总是将游标运行到onDateSet()类的DatePicker？请帮我澄清原因？