2020-04-03 20:17:46 to "yyyy-MM-dd'T'HH:mm:ss" format

Is there any way in java(java.util.* or Joda api ) to convert "2020-04-03 20:17:46" to "yyyy-MM-dd'T'HH:mm:ss"

new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss")
          .parse("2020-04-03 20:17:46")

its giving java.text.parseException always

Just for the case you are using Java 8 or above, make use of java.time.
See this simple example:

public static void main(String[] args) {
	// example datetime
	String datetime = "2020-04-03 20:17:46";
	// create a formatter that parses datetimes of this pattern
	DateTimeFormatter parserDtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
	// then parse the datetime with that formatter
	LocalDateTime ldt = LocalDateTime.parse(datetime, parserDtf);
	// in order to output the parsed datetime, use the default formatter (implicitly)
	System.out.println(ldt);
	// or format it in a totally different way
	System.out.println(ldt.format(
			DateTimeFormatter.ofPattern("EEE, dd. 'of' MMM 'at' hh-mm-ss a",
					Locale.ENGLISH)
			)
	);
}

This outputs

2020-04-03T20:17:46
Fri, 03. of Apr at 08-17-46 PM

Please note that this doesn't consider any time zone or offset, it just represents a date and time consisting of the passed or parsed years, months, days, hours, minutes and seconds, nothing else.

Do not use Date/Time API from java.util.* as most of them are now outdated. Use java.time API instead.

import java.io.IOException;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

public class Main {

	public static void main(String[] args) throws IOException {
		String strDatetime = "2020-04-03 20:17:46";
		DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
		LocalDateTime parsedDate = LocalDateTime.parse(strDatetime, formatter);
		System.out.println(parsedDate);
	}
}

Output:

2020-04-03T20:17:46

Learn more about DateTimeFormatter at https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html

Could this help you? http://tutorials.jenkov.com/java-internationalization/simpledateformat.html

First you need to parse the String with the old format, you will get a Date object. Then Create a new SimpleDateFormat with your new format, then you can format the Date object.

    String dateString = "2020-04-03 20:17:46";
    SimpleDateFormat output = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    Date date = sdf.parse(dateString);
    String formattedDate = output.format(date);

It do not work that way directly but if you still want to do it then, here is the process.

Create an object of SimpleDateFormat with pattern "yyyy-MM-dd HH:mm:ss")

use this to parse the string. Ultimately you are going to get date in both cases. Is there any specific reason for using T in pattern for dates which do not contain them?

Use LocalDateTime.

    Timestamp timestamp = Timestamp.parse("2020-04-03 20:17:46");

    LocalDateTime localDateTime = timestamp.toLocalDateTime();  

    System.out.println(localDateTime); // 2020-04-03T20:17:46