android之datepicker控件的用法

如下所示：

<?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;

@Override
 protected 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();
 }

@Override
 public 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;
 }

@Override
 public 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() {
   }

@Override
   public 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;
 }
}