如何在Java中检查不同的日期格式

Question

I am getting different date formats below dd-MM-yyyy,dd/MM/yyyy , yyyy-MM-dd , yyyy/MM/dd

SimpleDateFormat sm1 = new SimpleDateFormat("dd-MM-yyyy");
String date = "01-12-2013";
System.out.println("Date 1 is "+sm1.parse(date));
date = "2013-12-01";
System.out.println("Date 1 is "+sm1.parse(date));

the same simple date format gives the below result eventhough date format is wrong(ie:-2013-12-01).Below the results.

 Date 1 is Sun Dec 01 00:00:00 IST 2013
 Date 1 is Sun Jun 05 00:00:00 IST 7

Answer 1

您需要setLenient(false)才能使parse()方法在无法分析的情况下throw ParseException

Answer 2

I have tried Jigar Joshi's answer. ==========================code=======================================

SimpleDateFormat sm1 = new SimpleDateFormat("dd-MM-yyyy");
sm1.setLenient(false);
String date = "01-12-2013";
System.out.println("Date 1 is "+sm1.parse(date));
date = "2013-12-01";
System.out.println("Date 1 is "+sm1.parse(date));

=========================Result========================================

Date 1 is Sun Dec 01 00:00:00 CST 2013
Exception in thread "main" java.text.ParseException: Unparseable date: "2013-12-01"
    at java.text.DateFormat.parse(DateFormat.java:337)
    at workflow.Test.main(Test.java:14)

Answer 3

Your date format is dd-MM-yyyy . That means the parser is expecting some day, month, and year format.

From the SimpleDateFormat documentation : the number of pattern letters in a Number type formatter is the minimum . So, while 2013 wouldn't make sense in our mind, it fits within the formatter's bounds.

You have provided 2013-12-01 as to fit into that format. What it appears the formatter is doing is providing December 1 (insert timezone here), and then adding 2,013 days to it.

That turns out to be June 6, 7 AD . There's some wiggle room for your timezone (I'm not sure which of the five timezones IST represents is actually yours ).

So, believe it or not...the formatter is correct. Be very careful as to what kind of format you specify or allow in your dates!

If you don't want that parsed, then specify setLenient(false) on your instance of sm1 .