android使用datepicker计算年龄

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.example.datepicker.MainActivity" > <TextView  android:id="@+id/editText"  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:layout_centerHorizontal="true"  android:layout_centerVertical="true"  android:hint="选择你的出生年月" /> <Button  android:id="@+id/select"  android:onClick="SelectAge"  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:layout_alignBaseline="@+id/editText"  android:layout_alignBottom="@+id/editText"  android:layout_alignParentLeft="true"  android:text="选择年龄" /></RelativeLayout>

package com.example.datepicker;import java.text.SimpleDateFormat;import java.util.Date;import android.app.Activity;import android.app.DatePickerDialog;import android.app.DatePickerDialog.OnDateSetListener;import android.os.Bundle;import android.view.View;import android.view.Window;import android.widget.DatePicker;import android.widget.TextView;import android.widget.Toast;public class MainActivity extends Activity implements OnDateSetListener { private TextView mText; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  requestWindowFeature(Window.FEATURE_NO_TITLE);  setContentView(R.layout.activity_main);  mText = (TextView) findViewById(R.id.editText); } public void SelectAge(View v) {// 这设置默认显示的日期 我选的2000年1月1日       月这是从0开始 0 是一月  new DatePickerDialog(MainActivity.this, this, 2000, 0, 1).show(); } @Override public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {  // TODO Auto-generated method stub//  选择1月会是0 要把月份+1  Toast.makeText(MainActivity.this, "你选择的是" + year + "年" + (monthOfYear+1) + "月" + dayOfMonth + "日",    Toast.LENGTH_LONG).show();  SimpleDateFormat format = new SimpleDateFormat("yyyy");  int NowYear = Integer.parseInt(format.format(new Date()));  mText.setText("你今年" + (NowYear - year) + "岁"); }}