<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:orientation="vertical"android:layout_width="wrap_content"android:layout_height="wrap_content">
<TextView android:id="@+id/textViewDateDisplay" android:layout_width="wrap_content" android:layout_height="wrap_content" />
<Button android:id="@+id/btnPickDate"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="Change the date"/>
</LinearLayout>

package com.example.mars_2200_datepicker;import java.util.Calendar;import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.TextView;
import android.os.Build;public class MainActivity extends ActionBarActivity {private TextView textViewDateDisplay;private Button btnPickDate;private int mYear;private int mMonth;private int mDay;static final int DATE_DIALOG_ID = 0;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);textViewDateDisplay = (TextView) findViewById(R.id.textViewDateDisplay);btnPickDate = (Button) findViewById(R.id.btnPickDate);btnPickDate.setOnClickListener(new View.OnClickListener() {public void onClick(View v) {showDialog(DATE_DIALOG_ID);}});final Calendar c = Calendar.getInstance();mYear = c.get(Calendar.YEAR);mMonth = c.get(Calendar.MONTH);mDay = c.get(Calendar.DAY_OF_MONTH);updateDisplay();}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);return true;}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {// Handle action bar item clicks here. The action bar will// automatically handle clicks on the Home/Up button, so long// as you specify a parent activity in AndroidManifest.xml.int id = item.getItemId();if (id == R.id.action_settings) {return true;}return super.onOptionsItemSelected(item);}/*** A placeholder fragment containing a simple view.*/public static class PlaceholderFragment extends Fragment {public PlaceholderFragment() {}@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {View rootView = inflater.inflate(R.layout.fragment_main, container,false);return rootView;}}private void updateDisplay() {textViewDateDisplay.setText(new StringBuilder().append(mYear).append("-").append(mMonth + 1).append("-").append(mDay).append(" "));}private DatePickerDialog.OnDateSetListener mDateSetListener = new DatePickerDialog.OnDateSetListener() {public void onDateSet(DatePicker view, int year, int monthOfYear,int dayOfMonth) {mYear = year;mMonth = monthOfYear;mDay = dayOfMonth;updateDisplay();}};protected Dialog onCreateDialog(int id) {switch (id) {case DATE_DIALOG_ID:return new DatePickerDialog(this, mDateSetListener, mYear, mMonth,mDay);}return null;}
}