Question

So I am using dateString1.compareTo(dateString2) which does a lexicographic comparison with strings, based on the Unicode value of each character, and returns an int. Here is a code sample.

String dateString1 = "05-12-2012";
String dateString2 = "05-13-2012";
if (dateString1.compareTo(dateString2) <=0){
   System.out.println("dateString1 is an earlier date than dateString2");
}

Is this a wrong approach to compare dates in Java?

In my tests, I have not run into a situation where I have gotten unexpected result. I really do not want to create a Date object out of the string, if I don’t have to, because I am doing this inside a long running loop.

Ninja Edit
Gleaning from the answers below there is nothing wrong with comparing dates as a string if it is in yyyyMMdd format but if it is in any other format it will obviously result in error.

I actually have my date string as yyyyMMdd format in my actual code. (I typed the format wrong in the example I gave above.) So for now, I will just leave the code as it is, and add few lines of comments to justify my decision.

But I now see that comparing strings like this is very limiting and I will run into bugs if dba decides to change the date format down the road, which I don’t see happening.

Answer 1

I suggest you do the Right Thing (as described here) and convert to proper Date objects to compare. Worry about the performance impact if and when it actually impacts your application (which it probably won’t).