在MainActivity.java中setContentView()函数用的布局文件是不是你放置datePicker的xml？

我也是一样的情况啊，找到原因了吗？

public class MainActivity extends Activity {

private DatePicker datepicker;

private TimePicker timepicker;

private Calendar cal;

private int year;

private int month;

private int day;

private int hour;

private int minute;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

//获取一个日历对象

cal.getInstance();

//获取年月日时分秒的信息

year=cal.get(Calendar.YEAR);

month=cal.get(Calendar.MONTH)+1;

day=cal.get(Calendar.DAY_OF_MONTH);

hour=cal.get(Calendar.HOUR_OF_DAY);

minute=cal.get(Calendar.MINUTE);

//标题式

setTitle(year+"-"+month+"-"+day+"-"+hour+":"+minute);

//初始化控件

datepicker=(DatePicker) findViewById(R.id.datePicker1);

timepicker=(TimePicker) findViewById(R.id.timePicker1);

//datepicker初始化(第四个为事件监听器)

datepicker.init(year, cal.get(Calendar.MONTH), day, new OnDateChangedListener() {

@Override

public void onDateChanged(DatePicker view, int year, int monthofyear, int dayofmonth) {

setTitle(year+"-"+(monthofyear+1)+"-"+dayofmonth+"-"+hour+":"+minute);

}

});

}

}

代码?

你的代码呢？