Comparing date strings in Java

Use strings to handle dates in Java is not always the best option. For example, when it is a leap year, February has an extra day. Because strings can be seemingly correct, it is more appropriate to perform a conversion. Java validates that the date is correct.

You can convert strings to dates using the SimpleDateFormat class.

public static void main(String[] args) throws ParseException {
    String dateString1 = "05-12-2012";
    String dateString2 = "05-13-2012";

    SimpleDateFormat format = new SimpleDateFormat("dd-MM-yyyy");

    Date date1 = format.parse(dateString1);
    Date date2 = format.parse(dateString2);

    if (date1.compareTo(date2) <= 0) {
        System.out.println("dateString1 is an earlier date than dateString2");
    }
}

To find out which parameters are allowed to check Customizing Formats (The Java™ Tutorials > Internationalization > Formatting)

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).