android - DatePickerDialog 监听器

Question

我正在制作一个使用 DatePickerDialog 的 Android 应用程序。预期的功能是让用户在对话框中选择一个日期，然后让 TextView 反射(reflect)所选日期。但是，当用户选择日期时，我找不到任何类型的点击监听器来通知我的 Activity。我正在寻找一种方法来检测用户何时选择了日期，但来 self 的主要 Activity 。这是我的 DatePickerDialog 类:

public class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener {

private GregorianCalendar date;

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    // Use the current date as the default date in the picker
    final Calendar c = Calendar.getInstance();
    int year = c.get(Calendar.YEAR);
    int month = c.get(Calendar.MONTH);
    int day = c.get(Calendar.DAY_OF_MONTH);

    // Create a new instance of DatePickerDialog and return it
    return new DatePickerDialog(getActivity(), this, year, month, day);
}

@Override
public void onDateSet(DatePicker datePicker, int year, int month, int day) {
    date = new GregorianCalendar(year, month, day);
}

public GregorianCalendar getDate() {
    return date;
}
}    

以及我启动对话框的代码:

DialogFragment datePicker = new DatePickerFragment();
datePicker.show(getSupportFragmentManager(), "datePicker");

我目前从一个扩展 Activity 的类中启动对话框，并且我正在寻找一种方法来检测用户是否从对话框中选择了日期。有什么建议吗？

Answer 1

我推荐阅读:Communicating with Other Fragments .

Activity 必须实现 DatePickerDialog.OnDateSetListener 接口(interface):

public class MyActivity extends ActionBarActivity implements DatePickerDialog.OnDateSetListener {
    ...

    public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
        // the user selected, now you can do whatever you want with it
    }
}

如果您将以下代码添加到 DialogPickerFragment 类，

Activity 将在用户选择日期时收到通知:

public class DatePickerFragment extends DialogFragment {
    private DatePickerDialog.OnDateSetListener mListener;

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        // Use the current date as the default date in the picker
        final Calendar c = Calendar.getInstance();
        int year = c.get(Calendar.YEAR);
        int month = c.get(Calendar.MONTH);
        int day = c.get(Calendar.DAY_OF_MONTH);

        // Create a new instance of DatePickerDialog and return it
        return new DatePickerDialog(getActivity(), mListener, year, month, day);
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);

        if (!(context instanceof DatePickerDialog.OnDateSetListener)) {
            throw new IllegalStateException("Activity must implement fragment's callbacks.");
        }

        mListener = (DatePickerDialog.OnDateSetListener) activity;
    }

    @Override
    public void onDetach() {
        super.onDetach();

        mListener = null;
    }
}