android - 从 Android 中的 DatePickerFragment 获取日期对象

Question

我在我的 android 应用程序中定义了 DatePickerFragment，这是它的代码:

public class DatePickerFragment extends DialogFragment implements        DatePickerDialog.OnDateSetListener {    private int year;    private int month;    private int day;    @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 view, int year, int month, int day) {        this.year = year;        this.month = month;        this.day = day;    }    public Date getDateFromDatePicker(){        Calendar calendar = Calendar.getInstance();        calendar.set(year, month, day);        return calendar.getTime();    }}

I want to retrieve the date from this date picker from TaskFragment, and set the "date" attribute in my class Task to be equal to the date selected

        // Method for date picker to appear once the "Due Date" button is clicked.
    datePickerButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            FragmentManager fm = getActivity().getFragmentManager();
            DatePickerFragment datePicker = new DatePickerFragment();
            datePicker.show(fm, "datePicker");

            task.setDate(datePicker.getDateFromDatePicker());
           //test
           System.out.println(task.getDate());


        }
    });

单击按钮时会出现日期选择器。但是，日期设置不正确，实际上是在按下日期按钮后立即设置的，而不是从选择器中选择日期时设置的。此外，在打印日期时，无论我选择什么日期，我都会得到以下信息:I/System.out:12 月 31 日星期三 10:47:38 GMT+00:00 2阅读此处的一些解决方案指导我定义 onDateSet 和 getDateFromDatePicker 方法，但它们似乎无法正常运行。非常感谢任何帮助，谢谢!

Answer 1

经过一番挖掘，我按照我在Android Programming: The Big Nerd Ranch Guide一书中读到的方法，清楚地指定了如何在两个 fragment 之间传递数据。以下是我遵循的步骤:

1. 设置目标 fragment :在这里，我通过 setTargetFragment 方法将接收日期的 fragment (在我的例子中是 TaskFragment)设为 DatePickerFragment 的目标 fragment

    // set taskFragment as the target fragment of DatePickerFragment
    datePicker.setTargetFragment(TaskFragment.this, 0);
    datePicker.show(fm, "datePicker");

1. 通过 DatePickerFragment 的 onDateSet 方法将日期发送到目标 Fragment。为此，我将带有日期的 Intent 传递给目标 fragment 的 onActivityResult 方法。

    public void onDateSet(DatePicker view, int year, int month, int day) {
        // create date object using date set by user
        Calendar calendar = Calendar.getInstance();
        calendar.set(year, month, day);
        Date date = calendar.getTime();

        if (getTargetFragment() == null)
            return;

        Intent intent = new Intent();
        intent.putExtra(DATE, date);

        // pass intent to target fragment
        getTargetFragment().onActivityResult(getTargetRequestCode(), Activity.RESULT_OK, intent);

1. 覆盖目标 fragment 中的 onActivityResult 方法以接受日期

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode != Activity.RESULT_OK){
            return;
        }

        if (requestCode == REQUEST_DATE){
            Date date = (Date) data.getSerializableExtra(DatePickerFragment.DATE);
            task.setDate(date);

        }
    }