android's DatePickerDialog and TimePickerDialog implementation

Layout (calendar.xml)

 android:orientation="vertical" android:layout_width="fill_parent"
 android:layout_height="fill_parent">
   android:layout_height="wrap_content" />
 

Java Class:

package org.ipiel.demo.layout;

import java.text.DateFormat;
import java.util.Calendar;

import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.TimePickerDialog;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.TextView;
import android.widget.TimePicker;

public class ChronoDemo extends Activity {
 DateFormat fmtDateAndTime=DateFormat.getDateTimeInstance();
 TextView dateAndTimeLabel;
 Calendar dateAndTime=Calendar.getInstance();
 
 DatePickerDialog.OnDateSetListener d=new DatePickerDialog.OnDateSetListener() {
  public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
   dateAndTime.set(Calendar.YEAR, year);
   dateAndTime.set(Calendar.MONTH, monthOfYear);
   dateAndTime.set(Calendar.DAY_OF_MONTH, dayOfMonth);
   updateLabel();
  }
 };
 
 TimePickerDialog.OnTimeSetListener t=new TimePickerDialog.OnTimeSetListener() {
  public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
   dateAndTime.set(Calendar.HOUR, hourOfDay);
   dateAndTime.set(Calendar.MINUTE, minute);
   updateLabel();
  }
 };
 
 @Override
 public void onCreate(Bundle icicle) {
  super.onCreate(icicle);
  setContentView(R.layout.calendar);
  
  Button btn=(Button)findViewById(R.id.dateBtn);
  btn.setOnClickListener(new View.OnClickListener() {
   public void onClick(View v) {
    new DatePickerDialog(
      ChronoDemo.this,
      d,
      dateAndTime.get(Calendar.YEAR),
      dateAndTime.get(Calendar.MONTH),
      dateAndTime.get(Calendar.DAY_OF_MONTH)).show();
   }
  });
  
  btn=(Button)findViewById(R.id.timeBtn);
  btn.setOnClickListener(new View.OnClickListener() {
   public void onClick(View v) {
    new TimePickerDialog(
      ChronoDemo.this,
      t,
      dateAndTime.get(Calendar.HOUR),
      dateAndTime.get(Calendar.MINUTE),
      true).show();
   }
  });
  
  dateAndTimeLabel=(TextView)findViewById(R.id.dateAndTime);
  updateLabel();
 }
 
 private void updateLabel() {
  dateAndTimeLabel.setText(fmtDateAndTime.format(dateAndTime.getTime()));
 }
}