For quick reference, this is how you can format a date as:
dd/mm/yyyy at hh:mm:ss
System.out.printf("Date: %1$te/%1$tm/%1$tY at %1$tH:%1$tM:%1$tS%n", new Date());
The % characters mark a placeholders for String content, the 1$ indicates that the first vararg should be used for each placeholder (there is only one varag value supplied), the letter ‘t’ in each placeholder indicates a [...]