Generate a current datestamp in Java

Question

What is the best way to generate a current datestamp in Java?

YYYY-MM-DD:hh-mm-ss

Pontiac

"when not using a database"? What?? Do you normally query a database to retrieve the current time? – Winfield

Do you want a String in that format or some sort of timestamp/date object? – Owsley

JohnMilikan: Inefficient tho' 'tis, you can select current date from sysibm.sysdummy1 (that's the DB2 variant, I cna't remember what Oracles dummy tables are called). You're right though, that's not the way I'd do it. – Haematogenous

I was trying to say that the data I am writing out is not being timestamped for me when I write it into a table. Also I was not wanting to use and Language packs from external vendors. Thanks very much for your help. I'll also try to be a bit more concise with my questions in future. Cheers. – Pontiac

Answer 1

Using the standard JDK, you will want to use java.text.SimpleDateFormat

Date myDate = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd:HH-mm-ss");
String myDateString = sdf.format(myDate);

However, if you have the option to use the Apache Commons Lang package, you can use org.apache.commons.lang.time.FastDateFormat

Date myDate = new Date();
FastDateFormat fdf = FastDateFormat.getInstance("yyyy-MM-dd:HH-mm-ss");
String myDateString = fdf.format(myDate);

FastDateFormat has the benefit of being thread safe, so you can use a single instance throughout your application. It is strictly for formatting dates and does not support parsing like SimpleDateFormat does in the following example:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd:HH-mm-ss");
Date yourDate = sdf.parse("2008-09-18:22-03-15");

Originative

As of 3.2 FastDateFormat supports parsing :) – Slabber

Answer 2

Date d = new Date();
String formatted = new SimpleDateFormat ("yyyy-MM-dd:HH-mm-ss").format (d);
System.out.println (formatted);

Winfield

Answer 3

There's also

long timestamp = System.currentTimeMillis() 

which is what new Date() (@John Millikin) uses internally. Once you have that, you can format it however you like.

Owsley

Answer 4

SimpleDateFormatter is what you want.

Garnish

Answer 5

final DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd:hh-mm-ss");

formatter.format(new Date());

The JavaDoc for SimpleDateFormat provides information on date and time pattern strings.

Selfconfessed