Kotlin - 日期选择器对话框 - 如何在日期选择器对话框中显示以前选择的日期

Question

我有两个文本视图可以在 Android 的 DatePicker 对话框中设置日期。

我已经完成了 startDate(From Date) 和 endDate(To Date) 的验证，如下所示：

 /**
 * Dialog for selecting custom date.
 * */
private fun openDatePickerDialog(view: TextView, dateType: String) {
    activity?.let { KeyboardUtils.hideKeyboard(it) }
    val calendar = Calendar.getInstance()
    val dialog = DatePickerDialog(activity, { _, year, month, day_of_month ->
        calendar[Calendar.YEAR] = year
        calendar[Calendar.MONTH] = month
        calendar[Calendar.DAY_OF_MONTH] = day_of_month
        Log.e(">>>>>>>>>> ", ">>>>>>>>>> else")

        val myFormat = OverAllAppDateDisplayFormat
        val sdf = SimpleDateFormat(myFormat, Locale.getDefault())
        view.text = sdf.format(calendar.time).toString()
        when (dateType) {
            "from" -> {
                filterDateFrom = view.text.toString()
            }
            "to" -> {
                filterDateTo = view.text.toString()
            }
        }
    }, calendar[Calendar.YEAR], calendar[Calendar.MONTH], calendar[Calendar.DAY_OF_MONTH])

    if (view.id == R.id.tvDateTo && filterDateFrom.isNotEmpty() && filterDateFrom.contains("-")) {
        val sdf = SimpleDateFormat(OverAllAppDateDisplayFormat)
        try {
            val mDate = sdf.parse(filterDateFrom)
            dialog.datePicker.minDate = mDate.time
            dialog.datePicker.maxDate = calendar.timeInMillis
        } catch (e: ParseException) {
            e.printStackTrace()
        }
    } else if (view.id == R.id.tvDateFrom && filterDateTo.isNotEmpty() && filterDateTo.contains("-")) {
        val sdf = SimpleDateFormat(OverAllAppDateDisplayFormat)
        try {
            val mDate = sdf.parse(filterDateTo)
            dialog.datePicker.maxDate = mDate.time
        } catch (e: ParseException) {
            e.printStackTrace()
        }
    } else {
        //by default max date
        dialog.datePicker.maxDate = calendar.timeInMillis
    }
    dialog.show()
}

现在我想用特定文本视图上设置的最后日期打开这个对话框， 即，如果在 textView 上设置了 24-05-2021，则 datePicker 对话框应打开并选择相同的日期。

我需要在哪里改变才能实现这个目标？

谢谢。

Answer 1

您创建 DatePickerDialog 的方法是正确的。一旦日期选择器打开但您的日历实例错误，您正在使用 this 构造函数预先选择您的日期。

您使用的是val calendar = Calendar.getInstance()，它基本上表示当前时间戳。为了显示选定的时间，您需要先操作日历实例来设置日期，然后再将其传递给日期选择器对话框。

以下是正确的代码 sn-p:

val calendar = Calendar.getInstance()
calendar[Calendar.YEAR] = year // set your year to pre-select it on dialog
calendar[Calendar.MONTH] = month // set your month to pre-select it on dialog
calendar[Calendar.DAY_OF_MONTH] = day_of_month // set your day to pre-select it on dialog
val dialog = DatePickerDialog(
        activity,
        { _, year, month, day_of_month -> },
        calendar[Calendar.YEAR], // Using the same calendar instance here as above will do the trick
        calendar[Calendar.MONTH],
        calendar[Calendar.DAY_OF_MONTH]
)

Answer 2

您可以使用updateDate 方法更新 DatePicker 的日期。

只需像下面这样更改您的代码

if (view.id == R.id.tvDateTo && filterDateFrom.isNotEmpty() && filterDateFrom.contains("-")) {
        val sdf = SimpleDateFormat(OverAllAppDateDisplayFormat)
        try {
            val mDate = sdf.parse(filterDateFrom)
            dialog.datePicker.minDate = mDate.time
            dialog.datePicker.maxDate = calendar.timeInMillis
            //New Code
            val calendar = Calendar.getInstance()
            calendar.time = mDate
            dialog.datePicker.updateDate(calendar[Calendar.YEAR], 
                calendar[Calendar.MONTH], calendar[Calendar.DAY_OF_MONTH])

        } catch (e: ParseException) {
            e.printStackTrace()
        }
    } else if (view.id == R.id.tvDateFrom && filterDateTo.isNotEmpty() && filterDateTo.contains("-")) {
        val sdf = SimpleDateFormat(OverAllAppDateDisplayFormat)
        try {
            val mDate = sdf.parse(filterDateTo)
            dialog.datePicker.maxDate = mDate.time
            //New Code
            val calendar = Calendar.getInstance()
            calendar.time = mDate
            dialog.datePicker.updateDate(calendar[Calendar.YEAR], 
                calendar[Calendar.MONTH], calendar[Calendar.DAY_OF_MONTH])
        } catch (e: ParseException) {
            e.printStackTrace()
        }
    } 

Answer 3

问题是您总是在重新创建 openDatePickerDialog，因此会创建对话框的新实例。当前实例没有提供给前一个对话框实例的数据。因此，您可以将日期选择器对话框设置为单个实例，也可以将所选日期存储在全局变量中。

如果要实现不修改当前对话框。您需要将日期数据存储在全局变量中，而不是像这样存储来自日期集侦听器的日期数据

        calendar[Calendar.YEAR] = year
        calendar[Calendar.MONTH] = month
        calendar[Calendar.DAY_OF_MONTH] = day_of_month

您可以创建 3 个全局变量 day,month,year 并像这样存储来自日期集侦听器的数据

        this.year = year
        this.month = month
        this.day = day_of_month

并在创建对话框时使用新创建的变量作为日期数据，以在日期选择器对话框中显示数据以前的日期数据。

因此最终代码将如下所示

 var day = -1
 var year = -1
 var month = -1

 private fun openDatePickerDialog(view: TextView, dateType: String) {
    activity?.let { KeyboardUtils.hideKeyboard(it) }
    val calendar = Calendar.getInstance()

    if (day==-1 && month==-1 && year == -1) {
            year = calendar.get(Calendar.YEAR)
            month = calendar.get(Calendar.MONTH)
            day = calendar.get(Calendar.DAY_OF_MONTH)
        }    

    val dialog = DatePickerDialog(activity, { _, year, month, day_of_month ->
        this.year = year
        this.month = month
        this.day = day_of_month
        Log.e(">>>>>>>>>> ", ">>>>>>>>>> else")

        val myFormat = OverAllAppDateDisplayFormat
        val sdf = SimpleDateFormat(myFormat, Locale.getDefault())
        view.text = sdf.format(calendar.time).toString()
        when (dateType) {
            "from" -> {
                filterDateFrom = view.text.toString()
            }
            "to" -> {
                filterDateTo = view.text.toString()
            }
        }
    }, year, month, day)

    if (view.id == R.id.tvDateTo && filterDateFrom.isNotEmpty() && filterDateFrom.contains("-")) {
        val sdf = SimpleDateFormat(OverAllAppDateDisplayFormat)
        try {
            val mDate = sdf.parse(filterDateFrom)
            dialog.datePicker.minDate = mDate.time
            dialog.datePicker.maxDate = calendar.timeInMillis
        } catch (e: ParseException) {
            e.printStackTrace()
        }
    } else if (view.id == R.id.tvDateFrom && filterDateTo.isNotEmpty() && filterDateTo.contains("-")) {
        val sdf = SimpleDateFormat(OverAllAppDateDisplayFormat)
        try {
            val mDate = sdf.parse(filterDateTo)
            dialog.datePicker.maxDate = mDate.time
        } catch (e: ParseException) {
            e.printStackTrace()
        }
    } else {
        //by default max date
        dialog.datePicker.maxDate = calendar.timeInMillis
    }
    dialog.show()
}