android 入门 datepicker timepicker

package com.zte.android.lession;

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

public class Activity_008_datepicker extends Activity
{
	private DatePicker datePicker ;
	private TimePicker timePicker ;
	private TextView txt ;
	private Button getTimeBtn ;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		
		setContentView(R.layout.activity_008_clock_layout);
		//实例化组件
		datePicker = (DatePicker)findViewById(R.id.l008_datePicker1);
		timePicker = (TimePicker)findViewById(R.id.l008_timePicker1);
		txt = (TextView)findViewById(R.id.l008_textView1);
		getTimeBtn = (Button)findViewById(R.id.l008_button1);
		
		//set listener
		getTimeBtn.setOnClickListener(btnListener);
	}
	
	private OnClickListener btnListener = new OnClickListener() {
		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			//获取日期
			int year = datePicker.getYear();
			int month = datePicker.getMonth()+1;
			int day = datePicker.getDayOfMonth();
			//获取时间
			int hour = timePicker.getCurrentHour();
			int minute = timePicker.getCurrentMinute();
			//设置时间
			txt.setText(year+" "+month+" "+day+" "+hour+":"+minute);
		}
	};
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <DatePicker
        android:id="@+id/l008_datePicker1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TimePicker
        android:id="@+id/l008_timePicker1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <Button
        android:id="@+id/l008_button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="获取时间" />

    <TextView
        android:id="@+id/l008_textView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="" />

</LinearLayout>