Formatting timestamp to Date format-CodePudding

I have a question. I need to convert and display the data from database which it's a timestamp to date format only. *the format is dd/MM/yyyy

Currently I writng the code like this but the error says "Cannot format given Object as a Date"

xi.setItem("Dte",db.getDataAt(i,
           new SimpleDateFormat("dd/MM/yyyy").format("date_column_from_db")));

this is the example of the date column in the database: 20220321211529042 (basically it is a timestamp)

and I want to convert and display the data to date format only, like this: 21/03/2022

Hope to get solution. Thank you!

CodePudding user response：

Your use of the term 'timestamp' is misleading - it is really an encoded string.

You will need to decode the DB string and then recode it in the new format you want. Something like:

    String timestring = "20220321211529042";
    var parsedTimestamp = DateTimeFormatter.ofPattern("yyyyMMdd").parse(timestring.substring(0, 8));
    System.out.println(DateTimeFormatter.ofPattern("dd/MM/yyyy").format(parsedTimestamp));

In this case I've used substring to discard the time portion but if you want that you could extend the formatter used for parsing to include it.

CodePudding user response：

Just test the below code, format() method only allows Date or Number as an argument, String is invalid.

String column = new SimpleDateFormat("dd/MM/yyyy").format(20220321211529042L);
System.out.println("column = "   column);

DateFormat source may be more detailed https://developer.classpath.org/doc/java/text/DateFormat-source.html

public final StringBuffer format(Object obj, StringBuffer toAppendTo,
                                 FieldPosition fieldPosition)
{
    if (obj instanceof Date)
        return format( (Date)obj, toAppendTo, fieldPosition );
    else if (obj instanceof Number)
        return format( new Date(((Number)obj).longValue()),
                      toAppendTo, fieldPosition );
    else
        throw new IllegalArgumentException("Cannot format given Object as a Date");
}