I have a date pass from Angular frontend to Java backend.

The date format I received from frontend is: Wed Mon 26 11:11:59 SGT 2022 and is in Java Date object

How can I convert this format to dd/MM/yyyy and the final output should be 26/12/2022 in Java Date format.

Currently my code is like this:

SimpleDateFormat sdf = new SimpleDateFormat("EE MMM dd HH:mm:ss z yyyy",
                                        Locale.ENGLISH);

SimpleDateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");

Date formattedDate = dateFormat.parse(sdf.format(dateFromFrontend));

===> formattedDate to save to DB

Parse Exception that I get:

java.text.ParseException: Unparseable date: "Mon Dec 26 12:43:19 SGT 2022"

CodePudding user response：

At first, You need to convert String to LocalDate. Then you apply your required format.

        import java.util.Locale;
        import java.text.SimpleDateFormat;
        import java.time.LocalDate;
        import java.time.format.DateTimeFormatter;
        public class Test {
        
            public static void main(String[] args) {
                String raw = "Mon Dec 26 11:11:59 SGT 2022";
                DateTimeFormatter dtf = DateTimeFormatter.ofPattern("EEE MMM dd HH:mm:ss z yyyy", Locale.ENGLISH);

                //Your Required Format
                DateTimeFormatter formatter = DateTimeFormatter.ofPattern("d/MM/yyyy");
        
                LocalDate dateTime = LocalDate.parse(raw, dtf);
          
                System.out.println(formatter.format(dateTime));
            }
        }

**

Output: 
java -cp /tmp/AogMnqEAHL Test
26/12/2022

**

CodePudding user response：

If you are using at least Java 8, then you should use the date-time API. The documentation for class java.time.format.DateTimeFormatter details the recognized pattern characters. Recommended to also indicate the Locale.

By the way, 26^th December, 2022 is a Monday and not a Wednesday. In the below code, using the example from your question, I get the following error message:

Exception in thread "main" java.time.format.DateTimeParseException: Text 'Wed Dec 26 11:11:59 SGT 2022' could not be parsed: Conflict found: Field DayOfWeek 1 differs from DayOfWeek 3 derived from 2022-12-26

Since the example in your question contains a time zone, the below code parses the string to a ZonedDateTime but you could also parse it to a different class, depending on your requirements – which aren't clear to me from your question.

import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;

public class Doctor {

    public static void main(String[] args) {
        String raw = "Mon Dec 26 11:11:59 SGT 2022";
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("EEE MMM dd HH:mm:ss z yyyy", Locale.ENGLISH);
        ZonedDateTime zdt = ZonedDateTime.parse(raw, dtf);
        System.out.println(zdt);
    }
}

Running the above code gives following output:

2022-12-26T11:11:59 08:00[Asia/Singapore]

If you want to save the date in your database, then the data type of the column in the database table should be a [database] date type. Hence you need to use JDBC so the format is not important since you need to convert the ZonedDateTime to a java.sql.Date.

java.sql.Date d = java.sql.Date.valueOf(zdt.toLocalDate());

where zdt is the value obtained in the code, above.