SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy-MM-dd HH:mm");请详细解释每一部分

Sure!

`SimpleDateFormat` is a class in Java that is used to format and parse dates in a specific pattern.

`"yyyy-MM-dd HH:mm"` is the pattern used to format the date. Let's break it down:

- `yyyy` represents the year in four digits. For example, 2022.
- `-` is a separator character.
- `MM` represents the month in two digits. For example, 01 for January and 12 for December.
- `-` is another separator character.
- `dd` represents the day in two digits. For example, 01 for the 1st of the month and 31 for the last day of the month.
- ` ` (a space) is another separator character.
- `HH` represents the hour in 24-hour format. For example, 00 for midnight and 23 for 11 PM.
- `:` is a separator character.
- `mm` represents the minute in two digits. For example, 00 for the top of the hour and 59 for the last minute of the hour.

So `SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy-MM-dd HH:mm");` creates a new `SimpleDateFormat` object called `sdf1` with the specified date pattern. This object can be used to format dates in this pattern or parse strings into dates using this pattern.