How to compare between two dates in java?

Question

Passing my salute to every single hard working developer,

and cheers to every struggler out there.

Actually i am here because i got stuck on a very basic problem.

I am building a client-server application, and i am confused about how to compare between two dates extracted from jtable (eventually i've never got across any operations on dates in general).

I've used this code:

public static final String DATE_FORMAT_NOW = "yyyy-MM-dd";

  public static String now() {
   Calendar cal = Calendar.getInstance();
   SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW);
   return sdf.format(cal.getTime());

   }

 public static void ColorTheCell2(JTable jTable2){
          jTable2.getColumn("Date d'expiration").setCellRenderer(
    new DefaultTableCellRenderer() {

        @Override
    public Component getTableCellRendererComponent
    (JTable table,Object value,boolean isSelected,boolean hasFocus,int row,int column){

    Calendar datetable=Calendar.getInstance();

    String date=value.toString();
    String day=""+date.substring(8).toString();
    String month=""+date.substring(5, 7).toString();
    String year=""+date.substring(0,4).toString();

   datetable.set(Integer.parseInt(year),Integer.parseInt(month),Integer.parseInt(day));
    Calendar curdate=Calendar.getInstance();

     String date1=now();
     String day1=""+date1.substring(8).toString();
     String month1=""+date1.substring(5, 7).toString();
     String year1=""+date1.substring(0,4).toString();
                curdate.set(Integer.parseInt(year1),Integer.parseInt(month1)+1,Integer.parseInt(day1));


            if(datetable.before(curdate)){

                setText(value.toString());
                setBackground(Color.red);
            }
            else{
                 setText(value.toString());
            }

return this;
 }
  });
    }

Thank you for your Time. Best regards

http://stackoverflow.com/questions/2592501/compare-dates-in-java — Bhesh Gurung, Oct 12 '11 at 22:22
Your code is very difficult to read, due to wildly inconsistent formatting. Don't make it difficult for people to help you. — Marcelo Cantos, Oct 12 '11 at 22:23
For better help sooner, post an [SSCCE](http://pscode.org/sscce.html). (As opposed to expanding the code snippets.) And please indent the code more logically. — Andrew Thompson, Oct 12 '11 at 22:48

JB Nizet · Answer 1 · 2011-10-12T22:42:10.800

You don't tell what the type of the value in the cell is. If it's a String, then you're doing it wrong: it should be a Date, and the renderer should use a DateFormat to render the date (in addition to setting the appropriate background. This will, for example, allow sorting the table chronologically rather than lexicographically.

If it's already a Date, then just compare it with the current date, using its compareTo method.

Your now() method is really strange, since it seems to return a String rather than a Date. The appropriate type to represent a date is Date, not String. Use a Date and format it using a DateFormat each time you need it as a String. Don't do the reverse (using a String and parsing it - manually - each time you need a Date).

+1 for the extensive explanation. Nitpicking (obviously a matter of taste, that is mine :-) - prefer domain specific api over general, that is before/after over compareTo. — kleopatra, Oct 13 '11 at 06:31

score 4 · Answer 2 · answered Oct 12 '11 at 22:32

4

Take a look at compareTo() in Calendar class

In general , I prefer using Joda Time API for dates and time related stuff in java.

answered Oct 12 '11 at 22:32

Bhaskar

7,443
5
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Bhesh Gurung · Answer 3 · 2011-12-19T23:52:51.260

If in Object value value is of type Date then cast it to Date -

Date valDate = (Date) value;

Or, if it's String then parse Date out of it -

Date valDate = new SimpleDateFormat("pattern in value").parse((String) value);

Get current date -

Date currDate = new Date();

And then you can use any of the following methods in Date class -

boolean after(Date when)
boolean before(Date when)
int compareTo(Date anotherDate)

e.g.

if(valDate.before(currDate)) {

    //...

API doc: Date, SimpleDateFormat

score 3 · Answer 4 · answered Oct 12 '11 at 22:27

3

Date implements the Comparable interface, therefore you can use the method compareTo() to compare between two dates. Same thing for Calendar, just use its compareTo() method

answered Oct 12 '11 at 22:27

Óscar López

232,561
37
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How to compare between two dates in java?

4 Answers4