Determine if a String is a valid date before parsing

Question

I have this situation where I am reading about 130K records containing dates stored as String fields. Some records contain blanks (nulls), some contain strings like this: \'

Answer 1

Looks like three options if you only have two, known formats:

• check for the presence of - or / first and start with that parsing for that format.
• check the length since "dd-MMM-yy" and "dd/MM/yyyy" are different
• use precompiled regular expressions

The latter seems unnecessary.