无法比较两个Java日期，使用SimpleDateFormat“ dd / MM / YYYY hh：mm：ss a”将String转换为Date时转换无效

Question

In my application I need to compare two different dates given in below formats.

Inputs: there are 2 input dates in String format.

String actual="11/12/2012 11:26:04 AM";
String expected="21/12/2012 09:49:12 AM";

I am trying to use below java code for comparision.

---

SimpleDateFormat format= new SimpleDateFormat("dd/MM/YYYY hh:mm:ss a");
Date date1 = format.parse(actual);
System.out.println("Formated date1 is: "+format.format(date1).toString());       
// prints  :  01/01/2012 11:26:04 AM  Why????

Date date2= format.parse(expected);
System.out.println("Formated date2 is: "+format.format(date2).toString());        
// prints :  01/01/2012 09:49:12 AM  Why????

Calendar cal1 = Calendar.getInstance();
Calendar cal2 = Calendar.getInstance();
cal1.setTime(date1);
cal2.setTime(date2);
if( !(cal1.compareTo(cal2)<=0))
{
 result=false;
 String errMsg +="Actual:"+actual+" date is not before or equal to expected:"+expected+" date\n";
 System.out.println(errMsg);
}

---

But the above code is not working as expected. please check the wrong output mentioned in comments

I think there is something wrong with the formatting. can anyone please help me.

Answer 1

your format should be :

SimpleDateFormat format= new SimpleDateFormat("dd/MM/yyyy hh:mm:ss a");

Notice year in lowercase y

Answer 2

Try:

SimpleDateFormat format= new SimpleDateFormat("dd/MM/yyyy hh:mm:ss a");

The Ys should be lowercase.

Answer 3

You can use Joda Time . It has really nice methods, like isBefore()

String actual = "11/12/2012 11:26:04 AM";
String expected = "21/12/2012 09:49:12 AM";

DateTimeFormatter fmt = DateTimeFormat.forPattern("dd/MM/YYYY hh:mm:ss a");
DateTime dateTime1 = fmt.parseDateTime(actual);
DateTime dateTime2 = fmt.parseDateTime(expected);


if (dateTime1.isBefore(dateTime2)) {
    System.out.println("awesome");
}