string dsf = endDateTime.ToString("yyyy-MM-dd HH:00:00"); DateTime startDateTime = DateTime.Parse(dsf);怎么简写成一步

你可以使用`DateTime.TryParseExact`方法来进行一步操作，这个方法可以直接尝试解析字符串并返回`DateTime`对象，如果解析成功则返回`true`。这样简化后的代码如下：

DateTime? startDateTime = DateTime.TryParseExact(dsf, "yyyy-MM-dd HH:mm:ss", null, System.Globalization.DateTimeStyles.None, out DateTime parsedDateTime);
if (startDateTime.HasValue)
{
    startDateTime = parsedDateTime;
}
else
{
    // 如果解析失败，这里可以添加错误处理或默认值逻辑
}

在这个版本中，`TryParseExact`方法试图根据指定格式将字符串转换为`DateTime`。如果解析成功，结果被赋值给`parsedDateTime`，然后设置`startDateTime`。如果解析失败（`startDateTime.Value`为`null`），你需要额外处理这种情况。

相关问题

SimpleDateFormat dsf = new SimpleDateFormat("yyyy-MM"); String date = dsf.format(new Date()); Calendar calendar = Calendar.getInstance();

This code creates a SimpleDateFormat object with the format "yyyy-MM", which represents the year and month in a specific pattern. It then formats the current date using this format and stores it in a String variable called "date". Finally, it creates a Calendar object and sets it to the current date and time using the getInstance() method.

SimpleDateFormat dsf = new SimpleDateFormat("yyyy-MM");

This code creates a new instance of the SimpleDateFormat class with the format pattern "yyyy-MM", which represents the year and month in the format of "YYYY-MM", such as "2021-09". This pattern can be used to parse or format dates in this format.