将 DatePicker DialogFragment 设置为特定日期

Question

我有以下日期选择器对话框片段，它工作得很好，并将编辑文本中的日期设置为日期选择器中选择的日期。如果edittext不为空，我需要做的是将日期选择器中的日期设置为edittext中的日期。我的对话片段是：

public class DatePickerFragment : Android.Support.V4.App.DialogFragment, DatePickerDialog.IOnDateSetListener
{
    // TAG can be any string of your choice.
    public static readonly string TAG = "X:" + typeof(DatePickerFragment).Name.ToUpper();

    // Initialize this value to prevent NullReferenceExceptions.
    Action<DateTime> _dateSelectedHandler = delegate { };

    public static DatePickerFragment NewInstance(Action<DateTime> onDateSelected)
    {
        DatePickerFragment frag = new DatePickerFragment();
        frag._dateSelectedHandler = onDateSelected;
        return frag;
    }

    public override Dialog OnCreateDialog(Bundle savedInstanceState)
    {
        DateTime currently = DateTime.Now;
        DatePickerDialog dialog = new DatePickerDialog(Activity,
                                                       this,
                                                       currently.Year,
                                                       currently.Month - 1,
                                                       currently.Day);

        return dialog;
    }

    public void OnDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth)
    {
        // Note: monthOfYear is a value between 0 and 11, not 1 and 12!
        DateTime selectedDate = new DateTime(year, monthOfYear + 1, dayOfMonth);
        Log.Debug(TAG, selectedDate.ToLongDateString());
        _dateSelectedHandler(selectedDate);
    }
}

我在点击编辑文本时调用片段，代码是：

        dob.Click += (sender, e) =>
        {
            DatePickerFragment frag = DatePickerFragment.NewInstance(delegate (DateTime time)
            {
                string thedate = time.ToShortDateString();
                if (Utils.Mid(thedate,2,1) == "/")
                {
                    thedate = "0" + thedate;
                }
                dob.Text = thedate;
            });
            frag.Show(SupportFragmentManager, DatePickerFragment.TAG);
        };

我尝试了几种我在 stackoverflow 上看到的方法，但都没有奏效。

Answer 1

我想通了。其实很简单。要将数据传递给片段，请使用捆绑包。我更改了对片段的调用以添加包含初始日期的包，如下所示：

        dob.Click += (sender, e) =>
        {
            Bundle bundlee = new Bundle();
            bundlee.PutString("initDate", dob.Text);
            DatePickerFragment frag = DatePickerFragment.NewInstance(delegate (DateTime time)
            {
                string thedate = time.ToShortDateString();
                if (Utils.Mid(thedate,2,1) == "/")
                {
                    thedate = "0" + thedate;
                }
                dob.Text = thedate;
            });
            frag.Arguments = bundlee;
            frag.Show(SupportFragmentManager, DatePickerFragment.TAG);
        };

然后在片段的OnCreateDialog 方法中，我从包中获取数据并设置日期选择器的初始日期，如下所示：

    public override Dialog OnCreateDialog(Bundle savedInstanceState)
    {
        Bundle bundlee = this.Arguments;
        int month = DateTime.Now.Month;
        int day = DateTime.Now.Day;
        int year = DateTime.Now.Year;
        string initDate = bundlee.GetString("initDate");
        if (initDate != "" && initDate != null)
        {
            month = Convert.ToInt32(Utils.Mid(initDate, 1, 2));
            day = Convert.ToInt32(Utils.Mid(initDate, 4, 2));
            year = Convert.ToInt32(Utils.Mid(initDate, 7, 4));

        }

        //DateTime currently = DateTime.Now;
        DatePickerDialog dialog = new DatePickerDialog(Activity,
                                                       this,
                                                       year,
                                                       month - 1,
                                                       day);

        return dialog;
    }

作为一个从 VB4 开始的终身 VB 程序员，我不能没有 Mid 函数，所以我在 c# 中创建了一个等效函数并将它放在我的 Utils 类中（以防你想知道它在哪里来自）：

class Utils
{
     public static string Mid(string input, int index, char newChar)

    {

        if (input == null)

        {

            throw new ArgumentNullException("input");

        }

        char[] chars = input.ToCharArray();

        chars[index - 1] = newChar;

        return new string(chars);

    }
    public static string Mid(string s, int a, int b)

    {

        string temp = s.Substring(a - 1, b);

        return temp;

    }
}