這是我敲的

?protected void onCreate(Bundle savedInstanceState) {

? ? ? ? super.onCreate(savedInstanceState);

? ? ? ? setContentView(R.layout.activity_main);

? ? ? ? //獲取日歷的一個對象

? ? ? ? cal = Calendar.getInstance();

? ? ? ? //獲取年月日時分秒的信息

? ? ? ? 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);

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

? ? ? ??

? ? ? ? date_Picker = (DatePicker)findViewById(R.id.date);

? ? ? ? time_Picker = (TimePicker)findViewById(R.id.time);

? ? ? ? tv_date = (TextView) findViewById(R.id.tv_date);

? ? ? ? tv_time = (TextView) findViewById(R.id.tv_time);

? ? ? ? tv_date.setText("現在日期："+year+"-"+(month+1)+"-"+day);

? ? ? ? tv_time.setText("現在時間："+hour+":"+minute);

? ? ? ??

? ? ? //初始化日期

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

//監聽日期的改變

? ? ? ? @Override

public void onDateChanged(DatePicker view, int year, int monthOfYear,

int dayOfMonth) {

// TODO Auto-generated method stub

//Toast.makeText(MainActivity.this, "現在時間："+year+"-"+(monthOfYear+1)+"-"+dayOfMonth, 0).show();

? ?tv_date.setText("現在日期："+year+"-"+(monthOfYear+1)+"-"+dayOfMonth); ??

? ?setTitle(year+"/"+(monthOfYear+1)+"/"+dayOfMonth);

? ? ? ? }

});

? ? ? ? //設置時間為24小時制

? ? ? ? time_Picker.setIs24HourView(true);

? ? ? ? time_Picker.setOnTimeChangedListener(new OnTimeChangedListener() {

@Override

public void onTimeChanged(TimePicker view, int hourOfDay, int minute) {

// TODO Auto-generated method stub

tv_time.setText("現在時間："+hourOfDay+":"+minute);

setTitle(hourOfDay+":"+minute);

}

});

? ? ? ? new TimePickerDialog(this, new OnTimeSetListener() {

@Override

public void onTimeSet(TimePicker view, int hourOfDay, int minute) {

// TODO Auto-generated method stub

setTitle(hourOfDay+":"+minute);

}

},hour , minute, true).show();

? ? ? ??

? ? ? ??

? ? ? ??

? ? }

? ??

@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;

}

}

可能是你的布局界面沒有弄好,或者是TextView等之類的沒有聲明