The date-time API of java.util
and their formatting API, SimpleDateFormat
are outdated and error-prone. Note that java.sql.Timestamp
has inherited the same drawbacks as it extends java.util.Date
. It is recommended to stop using them completely and switch to the modern date-time API. For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.
You have mentioned,
My problem is I don't really know how to parse date like example:
"2020-12-28" into Timestamp
You have also mentioned,
And also am I right when you pare the yyyy-MM-dd string using the
SimpleDateFormat, it will set the HH:mm:ss part with default value is
00:00:0000?
From these two requirements, I infer that you need a date e.g. 2020-12-28
combined with the time e.g. 00:00:00
which is nothing but the start of the day. java.time
provides a clean API, LocalDate#atStartOfDay
to achieve this.
Demo:
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
String strDate = "2020-12-28";
// Parse the given date string into LocalDate. Note that you do not need a
// DateTimeFormatter to parse it as it is already in ISO 8601 format
LocalDate date = LocalDate.parse(strDate);
// Note: In the following line, replace ZoneId.systemDefault() with the required
// Zone ID which specified in the format, Continent/City e.g.
// ZoneId.of("Europe/London")
ZonedDateTime zdt = date.atStartOfDay(ZoneId.systemDefault());
// Print the default format i.e. the value of zdt#toString. Note that the
// default format omits seconds and next smaller units if seconds part is zero
System.out.println(zdt);
// Get and print just the date-time without timezone information
LocalDateTime ldt = zdt.toLocalDateTime();
System.out.println(ldt);
// Get and print zdt in a custom format
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("uuuu-MM-dd'T'HH:mm:ss.SSS", Locale.ENGLISH);
String formatted = zdt.format(dtf);
System.out.println(formatted);
}
}
Output:
2020-12-28T00:00Z[Europe/London]
2020-12-28T00:00
2020-12-28T00:00:00.000
Learn about the modern date-time API from Trail: Date Time.